A process for purification of an active pharmaceutical ingredient

Abstract

The present invention provides a process for the purification of an active pharmaceutical ingredient with montmorillonite to reduce heavy metal content. Particularly, the present invention provides a purified active pharmaceutical ingredient.

Description

[0001] FK24211-03-PAT-WO

[0002] A PROCESS FOR PURIFICATION OF AN ACTIVE PHARMACEUTICAL INGREDIENT

[0003] CROSS REFERENCE TO RELATED PATENT APPLICATION! S)

[0004] This patent application claims the benefit of Indian Patent Application No. 202411089618 filed on 19 Nov. 2024, which is incorporated by reference herein in its entirety.

[0005] FK24211-03-PAT-WO

[0006] FIELD OF THE INVENTION

[0007] The present invention relates to a process for purification of an active pharmaceutical ingredient (API). Particularly, the present invention relates to a process for the purification of an API by reducing heavy metal content.

[0008] BACKGROUND OF THE INVENTION

[0009] Heavy metals in APIs are a significant concern due to their potential toxicity. Common heavy metals that can be found in APIs include lead, cadmium, mercury, and arsenic. These metals can enter the manufacturing process through various sources, such as catalysts used in synthesis, environmental contamination, or leaching from equipment.

[0010] Agencies like the US Food and Drug Administration (FDA) have established guidelines to control and limit the presence of heavy metals impurities in drug products. For instance, the USP General Chapter <232> outlines specific limits for elemental impurities (heavy metals) and endorses a risk-based approach to ensure compliance. This approach involves assessing the potential sources of contamination and implementing appropriate controls to minimize the presence of these impurities in the final product.

[0011] There are several ways reported in the prior art to reduce heavy metal content in pharmaceuticals.

[0012] One such method is peptide remediation which involves peptides to bind to heavy metals, making them less toxic, however it does come with some disadvantages such as expensive synthesis of peptides which might limit the scalability of this method for large-scale applications, stability as well as specificity of peptides, regeneration, and disposal of metal bound peptides.

[0013] Another way to achieve reduced heavy metal content is by recrystallisation or precipitation of the product; however, this may result in the reduction of the product yield and may not be effective in purifying the APIs from heavy metals.

[0014] Carbon adsorption is another method for removing heavy metals, however this may generate byproducts that could be harmful to the product quality. Some disadvantages of carbon FK24211-03-PAT-WO adsorption for reducing heavy metals includes expensive regeneration of activated carbon, loss of efficiency over time, uncontrollable pore size as well as high ash content.

[0015] Other challenges with adsorption methods include removing different types of heavy metals at the same time, high retention time, and cycling stability of adsorbents.

[0016] When considering which method to use, the default is often to use standard methods such as crystallization, or carbon adsorption. Each method has its own advantages as well as disadvantages such as potential cost constraint and generation of additional impurities, however, the process costs, and its robustness, need to be considered during scale-up. Equal consideration needs to be given to the time taken to run the process and any impact that the removal method may have on the product yield.

[0017] There are various methods available for the removal of heavy metals from wastewater e.g. using nanomaterials and cloud point extraction, however all the reported methods are not equally suitable to be implemented in the pharmaceutical field.

[0018] The presence of heavy metal impurities in pharmaceutical products poses significant health risks, including toxicity and adverse side effects. These contaminants can originate from various sources during the manufacturing process, such as raw materials, catalysts, metal reagents, manufacturing equipment, and environmental exposure. The guidelines for monitoring of inorganic impurities in pharmaceutical and drug products, has been implemented by the European Pharmacopoeia (EP), the United States Pharmacopoeia (USP) and other International regulatory bodies. EMEA (European Medicines Evaluation Agency) guideline on the “specification limits for residues of metal catalysts or metal reagents” specifies maximum acceptable limits of metal residues in drug substances and excipients.

[0019] Heavy metals most often implicated in human poisoning are lead, mercury, arsenic, and cadmium. Some heavy metals, such as zinc, copper, chromium, iron, and manganese, are required by the body in small amounts, but these heavy metals can be toxic in higher quantities. The specification for heavy metals in active pharmaceutical ingredients is set taking into account its route of administration, maximum daily dosage, typical duration of FK24211-03-PAT-WO intake and risk assessment. The content of heavy metals in pharmaceutical substances is tested to control and quantify the levels of metals as a group due to the toxicity of the elements, but also due to the reason that heavy metal residues are a general marker for the quality of the product.

[0020] Therefore, there is a need to develop a cost effective, reproducible as well as industrially viable method for the removal of heavy metal to ensure the safety and efficacy of the APIs. The method involves the use of montmorillonite to reduce heavy metal content ensuring compliance with stringent regulatory standards and safeguarding public health.

[0021] OBJECT OF THE INVENTION

[0022] One aspect of the present invention addresses and overcomes one or more disadvantages with the prior art processes for reducing heavy metal in an API such as high operational costs, loss of yield, and generation of other impurities.

[0023] Another aspect of the present invention is to provide use of montmorillonite for the purification of an API.

[0024] A further aspect of the present invention is to provide a method for the removal of heavy metal content from an API by using montmorillonite.

[0025] Yet another aspect of the present invention is to provide an API with reduced heavy metal content.

[0026] SUMMARY OF THE INVENTION

[0027] The present invention provides a process for the purification of an API. Particularly, the present invention relates to a process for preparing a purified API, comprising combining a crude API, montmorillonite, and a liquid medium to provide a mixture, and isolating the purified API from the mixture.

[0028] In a first aspect, the present invention relates to a process for the purification of an API by reducing heavy metal content, comprising the steps of: a) mixing the API, which contains heavy metals, and a liquid medium; FK24211-03-PAT-WO b) treating the mixture of step a) with montmorillonite; and c) isolating the purified API.

[0029] In a second aspect, the present invention provides a purified API selected from the group consisting of 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt, Carfilzomib, saccharate, or Leucovorin Calcium, with reduced heavy metal content.

[0030] In a third aspect, the present invention relates to a process for the purification of saccharate by reducing heavy metal content, comprising the steps of: a) mixing potassium saccharate, which contains heavy metal, and a liquid medium; b) treating the mixture of step a) with montmorillonite; c) adding a salt-forming agent to the mixture obtained in step b), wherein the salt-forming agent is calcium chloride; and d) isolating calcium saccharate in which the saccharate is purified from heavy metals.

[0031] In a fourth aspect, the present invention provides a purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt: a) containing an iron metal content not exceeding 10.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt is substantially free from iron metal content, and / or b) containing a palladium metal content not exceeding 20.0 ppm, preferably not exceeding 17.0 ppm, more preferably the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from palladium metal content, and / or c) containing a nickel metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt is substantially free from nickel metal content, and / or d) containing a chromium metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2- FK24211-03-PAT-WO carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from chromium metal content.

[0032] In a fifth aspect, the present application provides a purified Carfilzomib: a) containing a nickel metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from nickel metal content, and / or b) containing a palladium metal content not exceeding 30.0 ppm, preferably not exceeding 28.0 ppm, more preferably the purified Carfilzomib is substantially free from palladium metal content, and / or c) containing an iron metal content not exceeding 30.0 ppm, preferably not exceeding 26.0 ppm, more preferably the purified Carfilzomib is substantially free from iron metal content, and / or d) containing a chromium metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from chromium metal content.

[0033] In a sixth aspect, the present application provides a purified Calcium saccharate tetrahydrate: a) containing an aluminium metal content not exceeding 50.0 ppm, preferably not exceeding 48.0 ppm, more preferably the purified Calcium saccharate tetrahydrate is substantially free from aluminium metal content, and / or b) containing a nickel metal content not exceeding 40.0 ppm, preferably not exceeding 35.0 ppm, more preferably the purified Calcium saccharate tetrahydrate is substantially free from nickel metal content.

[0034] In a seventh aspect, the present application provides a purified Leucovorin Calcium containing a lead metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, FK24211-03-PAT-WO more preferably the purified Leucovorin Calcium is substantially free from lead metal content.

[0035] In an eighth aspect, the present application provides the use of montmorillonite for the purification of an API by reducing heavy metal content, which are preferably selected from the group consisting of iron, nickel, palladium, chromium, aluminium, and lead.

[0036] In a ninth aspect, the present application provides a pharmaceutical composition comprising a purified API selected from the group consisting of 6-perdeoxy-6-per(2-carboxyethyl)thio- y-cyclodextrin sodium salt, Carfilzomib, saccharate, and Leucovorin Calcium, together with one or more pharmaceutically acceptable excipients.

[0037] DETAILED DESCRIPTION OF THE INVENTION

[0038] The present invention provides a process for the purification of an API by reducing heavy metal content. This process has several advantages such cost- effective process, highly pure API and commercial viability. Various methods for purification of an API are already known in the art. However, the processes known in the art have some disadvantages. Therefore, the present invention is focused on the use of montmorillonite for the purification of an API.

[0039] DEFINITIONS

[0040] The following definitions are used in connection with the present application unless the context indicates otherwise.

[0041] As used herein, the terms “comprises”, “comprising”, “includes”, “including”, “containing”, “having” or any other variation thereof, are intended to cover a nonexclusive inclusion.

[0042] As used herein, the term “mixing” means combining, blending, stirring, shaking, swirling, or agitating.

[0043] As used herein, the term “combining” means mixing, blending, stirring, shaking, swirling, or agitating. FK24211-03-PAT-WO

[0044] The terms “combining”, and “mixing” are used interchangeably. The term “mixing”, “mixture” or “combining” and the like may relate to any combination of substances to produce, for example, a solution of a solute in a solvent, a partial solution where the solute is not fully dissolved, a solution of two or more miscible liquids, a slurry and a suspension.

[0045] As used herein, the term “active pharmaceutical ingredient”, or API, is intended to be the industry-recognized definition, stated by the U.S. FDA: An API is "any substance or mixture of substances intended to be used in the manufacture of a drug product and that, when used in the production of a drug, becomes an active ingredient in the drug product. Such substances are intended to furnish pharmacological activity or other direct effect in the diagnosis, cure, mitigation, treatment or prevention of disease”. The term API includes any pharmaceutically acceptable salt, ester, solvate, polymorph, or other derivative thereof. As used herein, the term “heavy metal” is intended to denote ions of any one of the following metals: Pd, Al, As, Cd, Cr, Ni, Cu, Sn, Fe, Mn, Hg, Pb, Zn and Ti. Although the latter is not generally considered to be a heavy metal, it nevertheless constitutes a disruptive contamination for hydrogenation catalysts and, as such, is a heavy metal in the context of the present invention. The traces of heavy metals are particularly disruptive and, among them, Fe and Ti in particular, since they are commonly present in industrial fluids, owing to the nature of the equipment used to convey / treat them. Similarly, traces of Hg, which may be encountered in certain sources of H2, are also disruptive. By “traces” are meant amounts of the order of parts per billion (ppb), parts per million (ppm), or even tens of ppm.

[0046] As used herein, the term ‘heavy metal content” or “heavy metal” refers to heavy metal ions.

[0047] As used herein, the term “liquid medium” refers to a medium that is predominantly a liquid under the conditions of the process of the present invention, and encompasses solutions, dispersions, emulsions, and the like. As used herein, the term "liquid medium" can indicate a pure liquid or a combination of two or more liquids.

[0048] According to the process of the present invention, the liquid medium may comprise water or a non-aqueous liquid. Liquid medium may be selected from the group consisting of water, alcohol, halogenated solvent, aliphatic hydrocarbon, and polar aprotic solvent or a mixture FK24211-03-PAT-WO thereof, preferably the liquid medium is selected from the group consisting of water, methanol, ethanol, propanol, dichloromethane, dichloroethane, n-heptane, n-hexane, and acetone or mixture thereof, more preferably the liquid medium is selected from the group consisting of water, methanol, dichloromethane, n-heptane and acetone or a mixture thereof.

[0049] As used herein, the term “salt-forming agent” refers to a compound or substance capable of reacting with an active pharmaceutical ingredient (API) or precursor to form a salt. Such agents typically include acids, bases, or other ionic species that facilitate salt formation through neutralization or ion-exchange processes. Examples include inorganic acids (e.g., hydrochloric acid, sulfuric acid), organic acids (e.g., citric acid, tartaric acid), inorganic bases (e.g., sodium hydroxide, potassium hydroxide), and organic bases (e.g., triethylamine, ethanolamine) or inorganic salts (e.g. calcium chloride, sodium chloride, potassium chloride).

[0050] As used herein, the term “treating” as used hereinabove refers to suspending or stirring montmorillonite and an API in any of the liquid media described above.

[0051] As used herein, the term “isolating” refers to a process of obtaining the API from a reaction mixture, e.g. by means of filtration, decantation, extraction, distillation, evaporation, centrifugation, or a combination thereof.

[0052] As used herein, the term “purified" or "pure” as used herein refers to a compound that contains less amount of heavy metal content in the pharmaceutical active ingredient as compared to crude as specified in the present invention or that is substantially free from heavy metal content.

[0053] As used herein, the term “crude” as used herein refers to a compound that contains an amount of heavy metal that is determined to be not acceptable, e.g., as per a regulatory guideline.

[0054] “Montmorillonite” used herein refers to any grade of Montmorillonite available, for example natural Montmorillonite, purified Montmorillonite, Organically Modified Montmorillonite and activated Montmorillonite such as Montmorillonite K10, Montmorillonite K20 or Montmorillonite K30. FK24211-03-PAT-WO

[0055] As used herein, the term “substantially free” refers to a composition in which the content of heavy metals such as iron, lead, cadmium, mercury, arsenic, and similar elements is below a level that would materially affect the properties or intended use of the composition. In certain embodiments, “substantially free” means the heavy metal content is below the analytical detection limit, for example less than about 10 ppb for each individual metal, as measured by ICP-MS or an equivalent validated method.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, suitable methods and materials are described below. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

[0057] When an amount, concentration, or other value or parameter is given as either a range, preferred range, or a list of upper preferable values and / or lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range.

[0058] The present invention relates to a process for preparing a purified active pharmaceutical ingredient (API), comprising combining a crude API, montmorillonite, and a liquid medium to provide a mixture, and isolating the purified API from the mixture.

[0059] In a first aspect, the present invention relates to a process for the purification of an API by reducing heavy metal content, comprising the steps of: a) mixing the API, which contains heavy metal, and a liquid medium; b) treating the mixture of step a) with montmorillonite; and FK24211-03-PAT-WO c) isolating the purified API.

[0060] The API can be preferably selected from the group consisting of 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt, Carfilzomib, saccharate, and Leucovorin Calcium.

[0061] The saccharate may be provided in the form of calcium saccharate, preferably as calcium saccharate tetrahydrate.

[0062] The heavy metal can be preferably selected from the group consisting of iron, nickel, palladium, chromium, aluminium, and lead.

[0063] The liquid medium can be selected from the group consisting of water, alcohol, halogenated solvent, aliphatic hydrocarbon, and polar aprotic solvent or a mixture thereof.

[0064] Preferably, the liquid medium can be selected from the group consisting of water, methanol, ethanol, propanol, dichloromethane, dichloroethane, n-heptane, n-hexane, and acetone or mixture thereof.

[0065] More preferably, the liquid medium is selected from the group consisting of water, methanol, dichloromethane, n-heptane and acetone or a mixture thereof.

[0066] The API containing heavy metal in step a) may be mixed with a suitable liquid medium. The mixing of API with the liquid medium may be carried out at a temperature in a range from 15 to 45°C, preferably from 35°C to 40°C, more preferably from 20°C to 30°C.

[0067] The mixing of the API with the liquid medium may be carried out for 5 minutes to 2 hours, preferably for 10 minutes to 1.5 hours, more preferably for 15 minutes to 1 hours.

[0068] In a preferred embodiment, the mixing of the API with the liquid medium results in a clear solution.

[0069] The amount of the liquid medium to the API depends on the nature of API as well as the nature of the liquid medium, preferably the liquid medium used in step a) is 2 - 15 volumes per weight of API, preferably 3 to 12 volumes, more preferably 4 to 10 volumes per weight of API. FK24211-03-PAT-WO

[0070] The mixture of step a) is optionally treated with charcoal to remove coloured impurities before step b).

[0071] The mixture of step a) can be further treated with montmorillonite.

[0072] Step b) is preferably carried out at a temperature in the range of 15-55°C, more preferably in the range of 20-45°C, even more preferably in the range of 25-40°C.

[0073] Treatment of montmorillonite in Step b) may be carried out for 10 minutes to 5 hours, 20 minutes to 3 hours, more preferably for 30-60 minutes.

[0074] In some embodiments, the treatment of step b) is followed by filtration to remove montmorillonite.

[0075] The amount of Montmorillonite to the API depends on the nature of API as well as the percentage of desired reduction of heavy metal content in API, preferably 0.020 to 0.100 Montmorillonite is used per unit weight of API, preferably 0.025 to 0.080 Montmorillonite is used per unit weight of API, more preferably 0.030 to 0.060 Montmorillonite is used per unit weight of API.

[0076] Montmorillonite used in the process can be of any grade available, for example, natural Montmorillonite, purified Montmorillonite, Organically Modified Montmorillonite and activated Montmorillonite such as Montmorillonite K10, Montmorillonite K20 or Montmorillonite K30.

[0077] Filtrate of step b) may be optionally washed with a solvent selected from the group consisting of water, halogenated solvents such as dichloromethane.

[0078] In a preferred embodiment, the filtrate of step b), with or without washing, is mixed with a solvent selected from the group consisting of alcohol, halogenated solvent, nitrile solvent, ether and hydrocarbon solvent. Preferably the solvent is selected from group consisting of methanol, dichloromethane, heptane, tetrahydrofuran, acetonitrile, isopropanol, and methyl tert-butyl ether. The mixture may be cooled at a temperature in a range of -10 to 45°C, preferably in a range of -5 to 30°C, more preferably, -5 to 25°C. The mixture may be stirred for 1-10 hours, preferably 2- 8 hours, more preferably 2- 7 hours. FK24211-03-PAT-WO

[0079] In another preferred embodiment, following step b) the process may involve addition of a salt forming agent that is different from the API used in step a), particularly when the API is present in a salt form.

[0080] The purified API may be isolated from the mixture by conventional methods such as filtration, centrifugation etc., preferably it is isolated by filtration.

[0081] In step c) the API is isolated, preferably by filtration.

[0082] Purified API may be washed using a solvent selected from the group consisting of water, alcohol, hydrocarbon solvent. Preferably solvent is selected from group consisting of water, methanol, ethanol, acetone, isopropanol, dimethylsulfoxide, and heptane. The inventors of the present application found that montmorillonite is highly effective for reducing the content of heavy metal in an API. Other scavengers are not effective in reducing the heavy metal in an API. Implementing heavy metal removal processes as well as monitoring of heavy metals necessitates specialized knowledge. The inventors of the present application through extensive research selected the specific scavenger Montmorillonite for reducing the heavy metal.

[0083] The data showing the impact of various scavengers on Iron as heavy metal in 6-perdeoxy-6- per(2-carboxyethyl)thio-y-cyclodextrin sodium salt, as API, before and after treating with different scavengers are presented in Table 1. FK24211-03-PAT-WO

[0084] It is evident from the above comparison that Montmorillonite is highly effective in reducing heavy metal content.

[0085] The purification with Montmorillonite may be repeated two or more times, to further reduce the heavy metal content depending on the desired results. In a second aspect, the present application provides a process for the purification of an API selected from the group consisting of 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt, Carfilzomib, saccharate, or Leucovorin Calcium, by reducing heavy metal.

[0086] In a preferred embodiment, the present invention relates to a process for the purification of an API by reducing heavy metal, wherein API is 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt.

[0087] In a preferred embodiment, the present invention relates to a process for the purification of an API by reducing heavy metal, wherein API is 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt and the liquid medium is selected from the group consisting of water, methanol, ethanol, isopropyl alcohol, and acetone. In another preferred embodiment, the present invention relates to a process for the purification of an API by reducing heavy metal, wherein API is Carfilzomib. FK24211-03-PAT-WO

[0088] In another preferred embodiment, the present invention relates to a process for the purification of an API by reducing heavy metal, wherein API is Carfilzomib and liquid medium is selected from the group consisting of halogenated solvent.

[0089] In yet another preferred embodiment, the present invention relates to a process for the purification of an API by reducing heavy metal, wherein the API is saccharate,

[0090] In yet another preferred embodiment, the present invention relates to a process for the purification of an API by reducing heavy metal, wherein the API is saccharate and the liquid medium is water.

[0091] In yet another preferred embodiment, the present invention relates to a process for the purification of an API by reducing heavy metal, wherein the API is calcium saccharate, preferably calcium saccharate tetrahydrate.

[0092] In a preferred embodiment, the present invention relates to a process for the purification of an API by reducing heavy metal, wherein the API is Leucovorin Calcium.

[0093] In a more preferred embodiment, the present invention relates to a process for the purification of an API by reducing heavy metal content, wherein the API is Leucovorin Calcium and liquid medium is water.

[0094] The present application provides a purified API with reduced heavy metal.

[0095] In a third aspect, the present invention relates to a process for the purification of saccharate by reducing heavy metal content, comprising the steps of: a) mixing potassium saccharate, which contains heavy metal, and a liquid medium; b) treating the mixture of step a) with montmorillonite; c) adding a salt-forming agent to the mixture obtained in step b), d) isolating purified saccharate, preferably calcium saccharate in which the saccharate is purified from heavy metals. FK24211-03-PAT-WO

[0096] Potassium saccharate containing heavy metal in step a) may be mixed with a suitable liquid medium. The mixing of API with the liquid medium may be carried out at a temperature in a range from 15 to 45°C preferably from 35°C to 40°C.

[0097] Liquid medium for step a) is selected from the group consisting of water, alcohol, halogenated solvent, or a mixture thereof, preferably liquid medium is selected from water, methanol, ethanol, propanol, dichloromethane, dichloroethane, or mixture thereof. More preferably, liquid medium is water.

[0098] The mixing of potassium saccharate with the liquid medium may be carried out for 5 minutes to 30, preferably for 10 minutes to 20 minutes.

[0099] In a preferred embodiment, the process further comprises adjusting the pH of the reaction mixture to a range of about 6.0 to 7.5 to obtain a clear solution. Preferably, the pH adjustment is carried out by adding a base. Suitable bases include, without limitation, sodium hydroxide, potassium hydroxide, calcium hydroxide, or organic bases such as triethylamine and ethanolamine, preferably potassium hydroxide.

[0100] The amount of the liquid medium to the potassium saccharate used in step a) is 2 - 15 volumes per gram of potassium saccharate, preferably 3 to 12 volumes, more preferably 4 to 10 volumes per gram of potassium saccharate.

[0101] The mixture of step a) is optionally treated with charcoal to remove coloured impurities before step b).

[0102] The amount of Montmorillonite is 0.020 to 0.100 per unit weight of potassium saccharate, preferably 0.025 to 0.080 Montmorillonite per unit weight of potassium saccharate, more preferably 0.030 to 0.060 per unit weight of potassium saccharate.

[0103] Treatment with montmorillonite in Step b) may be carried out for 10 minutes to 5 hours, 20 minutes to 3 hours, more preferably for 30-60 minutes.

[0104] Step b) is preferably carried out at a temperature in the range of 15-55°C, more preferably in the range of 25-45°C, even more preferably in the range of 35-40°C. FK24211-03-PAT-WO

[0105] In some embodiments, the treatment of step b) is followed by filtration to remove montmorillonite. Preferably, the filtration may be through celite bed. The celite bed assembly may be rinsed with water. The combined filtrate and washings may be added into a reactor. Filtrate of step b) may be optionally washed with water,

[0106] In step c), salt forming agent may be added to the mixture obtained in step b).

[0107] The salt forming agent may be calcium chloride, preferably calcium chloride dihydrate.

[0108] The reaction mixture may be stirred at a temperature in a range of 15-55°C, more preferably in the range of 25-45°C, even more preferably in the range of 35-40°C.

[0109] The purified calcium saccharate may be isolated by stirring the mixture of step c) for 30 minutes to 3 hours, preferably 45 minutes to 2.5 hours, more preferably from 60 minutes to 2 hours followed by filtration.

[0110] In an embodiment, the solid may be optionally washed again with water and dried for 10 minutes to 30 minutes to obtain purified calcium saccharate.

[0111] In a preferred embodiment, the API is calcium saccharate tetrahydrate.

[0112] In a fourth aspect, the present invention provides a purified API selected from the group consisting of 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt, Carfilzomib, Calcium saccharate tetrahydrate, or Leucovorin Calcium, with reduced heavy metal content.

[0113] In a preferred embodiment, the present invention provides the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt containing iron metal more than 10.0 ppb, more than 100.0 ppb, more than 500.0 ppb. Preferably the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt containing iron metal in the range of 10.0 ppb to 10.0 ppm, 100.0 ppb to 10.0 ppm, or 500.0 ppb to 10.0 ppm, 1.0 ppm to 10.0 ppm. More preferably, the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt containing an iron metal content not exceeding 10.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from iron metal content. FK24211-03-PAT-WO

[0114] In another preferred embodiment, the present invention provides the purified 6-perdeoxy-6- per(2-carboxyethyl)thio-y-cyclodextrin sodium salt containing a palladium metal content more than 10.0 ppb, more than 100.0 ppb, more than 500.0 ppb. Preferably the purified 6- perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt containing palladium metal content in the range of 10.0 ppb to 20.0 ppm, 100.0 ppb to 20.0 ppm, or 500.0 ppb to 20.0 ppm, 1.0 ppm to 20.0 ppm. More preferably, the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt containing palladium metal content not exceeding 20.0 ppm, preferably not exceeding 17.0 ppm, more preferably the purified 6- perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from palladium metal content.

[0115] In another preferred embodiment, the present invention provides the purified 6-perdeoxy-6- per(2-carboxyethyl)thio-y-cyclodextrin sodium salt containing a nickel metal content more than 10.0 ppb, more than 100.0 ppb, more than 500.0 ppb. Preferably the purified 6- perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt containing nickel metal content in the range of 10.0 ppb to 2.0 ppm, 100.0 ppb to 2.0 ppm, or 500.0 ppb to 2.0 ppm, 500.0 ppb to 1.0 ppm. More preferably, the purified 6-perdeoxy-6-per(2-carboxyethyl)thio- y-cyclodextrin sodium salt containing a nickel metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from nickel metal content.

[0116] In another preferred embodiment, the present invention provides the purified 6-perdeoxy-6- per(2-carboxyethyl)thio-y-cyclodextrin sodium salt containing a chromium metal content more than 10.0 ppb, more than 100.0 ppb, more than 500.0 ppb. Preferably the purified 6- perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt containing chromium metal content in the range of 10.0 ppb to 2.0 ppm, 100.0 ppb to 2.0 ppm, or 500.0 ppb to 2.0 ppm, 500.0 ppb to 1.0 ppm. More preferably, the purified 6-perdeoxy-6-per(2-carboxyethyl)thio- y-cyclodextrin sodium salt containing chromium metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2- FK24211-03-PAT-WO carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from chromium metal content.

[0117] In another embodiment, the present invention provides the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt containing: a) an iron metal content not exceeding 10.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from iron metal content, and b) a palladium metal content not exceeding 20.0 ppm, preferably not exceeding 17.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt is substantially free from palladium metal content.

[0118] In another embodiment, the present invention provides the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt containing: a) an iron metal content not exceeding 10.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from iron metal content, and b) a nickel metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from nickel metal content.

[0119] In another embodiment, the present invention provides the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt containing: a) an iron metal content not exceeding 10.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from iron metal content, and b) a chromium metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from chromium metal content. FK24211-03-PAT-WO

[0120] In another embodiment, the present invention provides the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt containing: a) a palladium metal content not exceeding 20.0 ppm, preferably not exceeding 17.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt is substantially free from palladium metal content, and b) a nickel metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from nickel metal content.

[0121] In another embodiment, the present invention provides the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt containing: a) a palladium metal content not exceeding 20.0 ppm, preferably not exceeding 17.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt is substantially free from palladium metal content, and b) a chromium metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from chromium metal content.

[0122] In another embodiment, the present invention provides the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt containing: a) a nickel metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from nickel metal content, and b) a chromium metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from chromium metal content.

[0123] In another embodiment, the present invention provides the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt containing: FK24211-03-PAT-WO a) an iron metal content not exceeding 10.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from iron metal content, and b) a palladium metal content not exceeding 20.0 ppm, preferably not exceeding 17.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt is substantially free from palladium metal content and c) a nickel metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from nickel metal content.

[0124] In another embodiment, the present invention provides the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt containing: a) an iron metal content not exceeding 10.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from iron metal content, and b) a palladium metal content not exceeding 20.0 ppm, preferably not exceeding 17.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt is substantially free from palladium metal content, and c) a chromium metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from chromium metal content.

[0125] In another embodiment, the present invention provides the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt containing: a) an iron metal content not exceeding 10.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from iron metal content, and FK24211-03-PAT-WO b) a nickel metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from nickel metal content, and c) a chromium metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from chromium metal content.

[0126] In another embodiment, the present invention provides the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt containing: a) a palladium metal content not exceeding 20.0 ppm, preferably not exceeding 17.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt is substantially free from palladium metal content, and b) a nickel metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from nickel metal content, and c) a chromium metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from chromium metal content.

[0127] In another embodiment, the present invention provides the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt containing: a) an iron metal content not exceeding 10.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from iron metal content, and b) a palladium metal content not exceeding 20.0 ppm, preferably not exceeding 17.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt is substantially free from palladium metal content, and FK24211-03-PAT-WO c) a nickel metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from nickel metal content, and d) a chromium metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from chromium metal content.

[0128] In a fifth aspect, the present application provides a purified Carfilzomib.

[0129] In a preferred embodiment, the present application provides the purified Carfilzomib containing a nickel metal content more than 10.0 ppb, more than 100.0 ppb, more than 500.0 ppb. Preferably the purified Carfilzomib containing a nickel metal content in the range of 10.0 ppb to 5.0 ppm, 100.0 ppb to 5.0 ppm, or 500.0 ppb to 5.0 ppm, 1.0 ppm to 4.0 ppm. More preferably, the purified Carfilzomib containing a nickel metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from nickel metal content.

[0130] In another preferred embodiment, the present application provides the purified Carfilzomib containing a palladium metal content more than 10.0 ppb, more than 100.0 ppb, more than 500.0 ppb. Preferably the purified Carfilzomib containing a palladium metal content in the range of 10.0 ppb to 30.0 ppm, 100.0 ppb to 30.0 ppm, or 500.0 ppb to 30.0 ppm, 1.0 ppm to 28.0 ppm. More preferably, the purified Carfilzomib containing a palladium metal content not exceeding 30.0 ppm, preferably not exceeding 28.0 ppm, more preferably the purified Carfilzomib is substantially free from palladium metal content.

[0131] In another preferred embodiment, the present application provides the purified Carfilzomib containing an iron metal content more than 10.0 ppb, more than 100.0 ppb, more than 500.0 ppb. Preferably the purified Carfilzomib containing an iron metal content in the range of 10.0 ppb to 30.0 ppm, 100.0 ppb to 30.0 ppm, or 500.0 ppb to 30.0 ppm, 1.0 ppm to 26.0 ppm. More preferably, the purified Carfilzomib containing an iron metal content not exceeding FK24211-03-PAT-WO

[0132] 30.0 ppm, preferably not exceeding 26.0 ppm, more preferably the purified Carfilzomib is substantially free from iron metal content.

[0133] In another preferred embodiment, the present application provides the purified Carfilzomib containing a chromium metal content more than 10.0 ppb, more than 100.0 ppb, more than 500.0 ppb. Preferably the purified Carfilzomib containing a chromium metal content in the range of 10.0 ppb to 5.0 ppm, 100.0 ppb to 5.0 ppm, or 500.0 ppb to 5.0 ppm, 1.0 ppm to 4.0 ppm. More preferably, the purified Carfilzomib containing a chromium metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from chromium metal content.

[0134] In another preferred embodiment, the present application provides the purified Carfilzomib containing: a) nickel metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from nickel metal content, and b) a palladium metal content not exceeding 30.0 ppm, preferably not exceeding 28.0 ppm, more preferably the purified Carfilzomib is substantially free from palladium metal content.

[0135] In another preferred embodiment, the present application provides the purified Carfilzomib containing: a) a nickel metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from nickel metal content, and b) an iron metal content not exceeding 30.0 ppm, preferably not exceeding 26.0 ppm, more preferably the purified Carfilzomib is substantially free from iron metal content.

[0136] In another preferred embodiment, the present application provides the purified Carfilzomib containing: FK24211-03-PAT-WO a) a nickel metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from nickel metal content, and b) a chromium metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from chromium metal content.

[0137] In another preferred embodiment, the present application provides the purified Carfilzomib containing: a) a palladium metal content not exceeding 30.0 ppm, preferably not exceeding 28.0 ppm, more preferably the purified Carfilzomib is substantially free from palladium metal content, and b) an iron metal content not exceeding 30.0 ppm, preferably not exceeding 26.0 ppm, more preferably the purified Carfilzomib is substantially free from iron metal content.

[0138] In another preferred embodiment, the present application provides the purified Carfilzomib containing: a) a palladium metal content not exceeding 30.0 ppm, preferably not exceeding 28.0 ppm, more preferably the purified Carfilzomib is substantially free from palladium metal content, and b) a chromium metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from chromium metal content.

[0139] In another preferred embodiment, the present application provides the purified Carfilzomib containing: a) an iron metal content not exceeding 30.0 ppm, preferably not exceeding 26.0 ppm, more preferably the purified Carfilzomib is substantially free from iron metal content, and FK24211-03-PAT-WO b) a chromium metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from chromium metal content.

[0140] In another preferred embodiment, the present application provides the purified Carfilzomib containing: a) an iron metal content not exceeding 30.0 ppm, preferably not exceeding 26.0 ppm, more preferably the purified Carfilzomib is substantially free from iron metal content, b) a palladium metal content not exceeding 30.0 ppm, preferably not exceeding 28.0 ppm, more preferably the purified Carfilzomib is substantially free from palladium metal content, and c) a chromium metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from chromium metal content.

[0141] In another preferred embodiment, the present application provides the purified Carfilzomib containing: a) an iron metal content not exceeding 30.0 ppm, preferably not exceeding 26.0 ppm, more preferably the purified Carfilzomib is substantially free from iron metal content, b) a chromium metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from chromium metal content, and c) a nickel metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from nickel metal content.

[0142] In another preferred embodiment, the present application provides the purified Carfilzomib containing: FK24211-03-PAT-WO a) a palladium metal content not exceeding 30.0 ppm, preferably not exceeding 28.0 ppm, more preferably the purified Carfilzomib is substantially free from palladium metal content, b) a chromium metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from chromium metal content, and c) a nickel metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from nickel metal content.

[0143] In another preferred embodiment, the present application provides the purified Carfilzomib containing: a) an iron metal content not exceeding 30.0 ppm, preferably not exceeding 26.0 ppm, more preferably the purified Carfilzomib is substantially free from iron metal content, b) a chromium metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from chromium metal content, and c) a nickel metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from nickel metal content.

[0144] In another preferred embodiment, the present application provides the purified Carfilzomib containing: a) a nickel metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from nickel metal content, FK24211-03-PAT-WO b) a palladium metal content not exceeding 30.0 ppm, preferably not exceeding 28.0 ppm, more preferably the purified Carfilzomib is substantially free from palladium metal content, c) an iron metal content not exceeding 30.0 ppm, preferably not exceeding 26.0 ppm, more preferably the purified Carfilzomib is substantially free from iron metal content, and d) a chromium metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from chromium metal content, and

[0145] In a sixth aspect, the present application provides a purified saccharate.

[0146] In a preferred embodiment, the present application provides a purified calcium saccharate,

[0147] In another preferred embodiment, the present application provides calcium saccharate tetrahydrate.

[0148] In a preferred embodiment, the present application provides the purified Calcium saccharate tetrahydrate containing an aluminium metal content more than 10.0 ppb, more than 100.0 ppb, more than 500.0 ppb. Preferably the purified Calcium saccharate tetrahydrate containing an aluminium metal content in the range of 10.0 ppb to 50.0 ppm, 100.0 ppb to 50.0 ppm, or 500.0 ppb to 50.0 ppm, 1.0 ppm to 48.0 ppm. More preferably, the purified Calcium saccharate tetrahydrate containing an aluminium metal content not exceeding 50.0 ppm, preferably not exceeding 48.0 ppm, more preferably the purified Calcium saccharate tetrahydrate is substantially free from aluminium metal content.

[0149] In another preferred embodiment, the present application provides the purified Calcium saccharate tetrahydrate containing a nickel metal content more than 10.0 ppb, more than 100.0 ppb, more than 500.0 ppb. Preferably the purified Calcium saccharate tetrahydrate containing a nickel metal content in the range of 10.0 ppb to 40.0 ppm, 100.0 ppb to 40.0 ppm, or 500.0 ppb to 40.0 ppm, 1.0 ppm to 35.0 ppm. More preferably, the purified Calcium saccharate tetrahydrate containing a nickel metal content not exceeding 40.0 ppm, preferably FK24211-03-PAT-WO not exceeding 35.0 ppm, more preferably the purified Calcium saccharate tetrahydrate is substantially free from nickel metal content.

[0150] In another preferred embodiment, the present application provides the purified Calcium saccharate tetrahydrate containing: a) an aluminium metal content not exceeding 50.0 ppm, preferably not exceeding 48.0 ppm, more preferably the purified Calcium saccharate tetrahydrate is substantially free from aluminium metal content, and, b) a nickel metal content not exceeding 40.0 ppm, preferably not exceeding 35.0 ppm, more preferably the purified Calcium saccharate tetrahydrate is substantially free from nickel metal content.

[0151] In a seventh aspect, the present application provides a purified Leucovorin Calcium.

[0152] In another embodiment, the present application provides the purified Leucovorin Calcium containing a lead metal content more than 10.0 ppb, more than 100.0 ppb, more than 500.0 ppb. Preferably the purified Leucovorin Calcium containing a lead metal content in the range of 10.0 ppb to 5.0 ppm, 100.0 ppb to 5.0 ppm, or 500.0 ppb to 5.0 ppm, 1.0 ppm to 4.0 ppm. More preferably, the purified Leucovorin Calcium containing a lead metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Leucovorin Calcium is substantially free from lead metal ion.

[0153] In an eighth aspect, the present application provides a use of montmorillonite for the purification of an API by reducing heavy metal content, which are preferably selected from the group consisting of iron, nickel, palladium, chromium, aluminium, and lead.

[0154] In a ninth aspect, the present application provides a pharmaceutical composition comprising a purified API selected from the group consisting of 6-perdeoxy-6-per(2-carboxyethyl)thio- y-cyclodextrin sodium salt, Carfilzomib, saccharate, and Leucovorin Calcium, together with one or more pharmaceutically acceptable excipients. The saccharate may be provided in the form of calcium saccharate, preferably as calcium saccharate tetrahydrate. FK24211-03-PAT-WO

[0155] In the context of pharmaceutical manufacturing, the application of montmorillonite for the purification of APIs offers a promising solution to mitigate heavy metal contamination. By incorporating montmorillonite into the purification process, it is possible to achieve significant reductions in heavy metal content, thereby enhancing the safety profile of the final pharmaceutical product.

[0156] Embodiments:

[0157] 1. A process for the purification of an API by reducing heavy metal content, comprising the steps of: a) mixing the API, which contains heavy metal, and a liquid medium; b) treating the mixture of step a) with montmorillonite; and c) isolating the purified API.

[0158] 2. The process according to embodiment 1 , wherein the API contains one or more heavy metals selected from the group consisting of iron, nickel, palladium, chromium, aluminium, and lead.

[0159] 3. The process of according to embodiment 1 or embodiment 2, wherein the API is selected from the group consisting of 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt, Carfilzomib, saccharate and Leucovorin Calcium.

[0160] 4. The process of according to embodiment 3, wherein API is 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt.

[0161] 5. The process of according to embodiment 4, wherein the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt contains: a) an iron metal content not exceeding 10.0 ppm, preferably not exceeding 4.0 ppm, more preferably is substantially free from iron metal content, and / or b) a palladium metal content not exceeding 20.0 ppm, preferably not exceeding 17.0 ppm, more preferably is substantially free from palladium metal content, and / or c) a nickel metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably is substantially free from nickel metal content, and / or FK24211-03-PAT-WO d) a chromium metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably is substantially free from chromium metal content.

[0162] 6. The process according to embodiment 3, wherein the API is Carfilzomib.

[0163] 7. The process according to embodiment 6, wherein the purified Carfilzomib contains: a) a nickel metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably is substantially free from nickel metal content, and / or b) a palladium metal content not exceeding 30.0 ppm, preferably not exceeding 28.0 ppm, more preferably is substantially free from palladium metal content, and / or c) an iron metal content not exceeding 30.0 ppm, preferably not exceeding 26.0 ppm, more preferably is substantially free from iron metal content, and / or d) a chromium metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably is substantially free from chromium metal content.

[0164] 8. The process according to embodiment 1, wherein in step a) API is potassium saccharate.

[0165] 9. The process according to embodiment 8, wherein after step b) the process involves adding a salt-forming agent.

[0166] 10. The process according to embodiment 9, wherein the salt-forming agent is calcium chloride.

[0167] 11. The process according to embodiment 3, wherein purified API is saccharate, preferably calcium saccharate, more preferably calcium saccharate tetrahydrate.

[0168] 12. The process according to embodiment 11 , wherein the purified Calcium saccharate tetrahydrate contains: a) an aluminium metal content not exceeding 50.0 ppm, preferably not exceeding 48.0 ppm, more preferably is substantially free from aluminium metal content, and / or b) a nickel metal content not exceeding 40.0 ppm, preferably not exceeding 35.0 ppm, more preferably is substantially free from nickel metal content.

[0169] 13. The process according to embodiment 3, wherein the API is Leucovorin Calcium.

[0170] 14. The process according to embodiment 13, wherein the purified Leucovorin Calcium contains a lead metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Leucovorin Calcium is substantially free from lead metal. FK24211-03-PAT-WO

[0171] 15. The process of any preceding embodiment, wherein the liquid medium is selected from the group consisting of water, alcohol, halogenated solvent, aliphatic hydrocarbon, and polar aprotic solvent or a mixture thereof, preferably the liquid medium is selected from the group consisting of water, methanol, ethanol, propanol, dichloromethane, dichloroethane, n-heptane, n-hexane, and acetone or mixture thereof, more preferably the liquid medium is selected from the group consisting of water, methanol, dichloromethane, n-heptane and acetone or a mixture thereof.

[0172] 16. The process of any preceding embodiment, wherein the mixture is provided at a temperature in the range of 15-55°C, preferably in the range of 20-45°C, more preferably in the range of 25-40°C.

[0173] 17. Purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt: a) containing an iron metal content not exceeding 10.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt is substantially free from iron metal content, and / or b) containing a palladium metal content not exceeding 20.0 ppm, preferably not exceeding 17.0 ppm, more preferably the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from palladium metal content, and / or c) containing a nickel metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt is substantially free from nickel metal content, and / or d) containing a chromium metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from chromium metal content.

[0174] 18. Purified Carfilzomib: a) containing a nickel metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from nickel metal content, and / or FK24211-03-PAT-WO b) containing a palladium metal content not exceeding 30.0 ppm, preferably not exceeding 28.0 ppm, more preferably the purified Carfilzomib is substantially free from palladium metal content, and / or c) containing an iron metal content not exceeding 30.0 ppm, preferably not exceeding 26.0 ppm, more preferably the purified Carfilzomib is substantially free from iron metal content, and / or d) containing a chromium metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from chromium metal content.

[0175] 19. Purified Calcium saccharate tetrahydrate: a) containing an aluminium metal content not exceeding 50.0 ppm, preferably not exceeding 48.0 ppm, more preferably the purified Calcium saccharate tetrahydrate is substantially free from aluminium metal content, and / or b) containing a nickel metal content not exceeding 40.0 ppm, preferably not exceeding 35.0 ppm, more preferably the purified Calcium saccharate tetrahydrate is substantially free from nickel metal content.

[0176] 20. Purified Leucovorin Calcium containing a lead metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Leucovorin Calcium is substantially free from lead metal content.

[0177] 21. Use of montmorillonite for the purification of an API by reducing heavy metal, which are preferably selected from the group consisting of iron, nickel, palladium, chromium, aluminium, and lead.

[0178] 22. A purified API selected from the group consisting of 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt, Carfilzomib, saccharate and Leucovorin Calcium, obtainable by the process according to any one of embodiment 1 , 2, 15 or 16.

[0179] 23. A pharmaceutical composition comprising a purified API selected from the group consisting of 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt, Carfilzomib, saccharate, and Leucovorin Calcium, together with one or more pharmaceutically acceptable excipients. FK24211-03-PAT-WO

[0180] 24. A process for the purification of saccharate by reducing heavy metal content, comprising the steps of:

[0181] (a) mixing potassium saccharate, which contains heavy metal, and a liquid medium;

[0182] (b) treating the mixture of step a) with montmorillonite;

[0183] (c) adding a salt-forming agent to the mixture obtained in step b), and

[0184] (d) isolating purified saccharate.

[0185] ABBREVIATIONS

[0186] API Active pharmaceutical ingredient

[0187] Ppm parts per million

[0188] Ppb parts per billion w / w weight by weight

[0189] Al Aluminium

[0190] As Arsenic

[0191] Cd Cadmium

[0192] Cr Chromium

[0193] Ni Nickel

[0194] Cu Copper

[0195] Sn Tin

[0196] Fe Iron

[0197] Mn Manganese

[0198] Hg Mercury

[0199] Pb Lead

[0200] Zn Zinc FK24211-03-PAT-WO

[0201] Ti Titanium

[0202] H2Hydrogen

[0203] Pd Palladium

[0204] EDTA Ethylenediaminetetraacetic acid

[0205] SiliaMetS TAAcONa SiliaMetS Triaminetetraacetate

[0206] U.S. FDA United States Food and Drug Administration

[0207] EXPERIMENTAL

[0208] Detailed experimental parameters according to the present invention are provided by the following examples, which are intended to be illustrative and not limiting of all possible embodiments of the invention.

[0209] Example 1: Purification of 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium

[0210] Crude 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium (50 g) was stirred in water (250 mL) at 20-30°C. The mixture was charcoalised followed by addition of montmorillonite (2 g) at 20-30°C. The reaction mixture was stirred at 20-30°C for 30-60 minutes. The mixture was filtered and washed with water (50 mL). Methanol (2000 mL) was added to filtrate and stirred at 50-55°C. Mixture was cooled to 25-30°C and stirred for 4-6 hours. The resulting mass was filtered, washed with methanol (100 mL X 2) and repeated the same treatment process & dried to give purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium.

[0211] Iron content in the crude and purified product is presented below:

[0212] Example 2: Purification of 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium FK24211-03-PAT-WO

[0213] Crude 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium (10 g), was stirred in water (90 mL) at 20-30°C. Then the mixture was treated by using activated charcoal (0.4 g) & Montmorillonite K10 (0.4 g) at 20-25°C and micron filtration, followed by lyophilisation of filtrate. The obtained lyophilized solid was repeated treatment by using activated charcoal (0.4 g) & Montmorillonite K10 (0.5 g) and followed by lyophilisation filtrate to obtain purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium.

[0214] Palladium content in the crude and purified product is presented below:

[0215] Example 3: Purification of 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium

[0216] Crude 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium (10 g), was stirred in water (90 mL) at 20-30°C. Then the mixture was treated by using activated charcoal (0.4 g) & Montmorillonite K10 (0.4 g) at 20-25°C and micron filtration, followed by lyophilisation of filtrate to obtain purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium. Nickel content in the crude and purified product is presented below:

[0217] Example 4: Purification of 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium FK24211-03-PAT-WO

[0218] Crude 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium (10 g), was stirred in water (90 mL) at 20-30°C. Then the mixture was treated by using activated charcoal (0.4 g) & Montmorillonite K10 (0.4 g), at 20-25°C and micron filtration, followed by lyophilisation of filtrate to obtain purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium. Chromium content in the crude and purified product is presented below:

[0219] Example 5: Purification of Carfilzomib

[0220] Crude Carfilzomib (10g) in dichloromethane (30 mL) was stirred at 20-30 °C for 15 minutes. The mixture was charcoalised followed by addition of montmorillonite (360 mg) at 20-30 °C. The reaction mass was stirred for 1 hour at 20°C. The mixture was filtered and washed with dichloromethane (10 mL). n-heptane (360 mL) was added to filtrate and stirred for 2 hours at -5 to -15°C. The resulting product was filtered, washed with n-heptane and dried to give purified Carfilzomib.

[0221] Heavy metal content in the crude and purified product is presented below:

[0222] Example 6: Purification of Leucovorin Calcium Calcium chloride (25 g) was mixed with water (800 mL) at 20-30°C. Leucovorin Calcium (90 -103 g) was added to the mixture followed by addition of montmorillonite (5 g) at 20- 30°C. The mixture was charcoalised (10g) and washed with water (1 OOmL). pH of the filtrate was adjusted to 7.3 -7.8 with 1 N NaOH solution followed by seeding with pure Leucovorin FK24211-03-PAT-WO calcium (1.0g) at 20-30°C. The reaction mass was stirred for 40 - 45 hours at 20-25°C.The reaction mass was filtered and washed with purified water (5-10°C, 150 mL) and acetone (lOOmL), and dried for 1-2 hours under nitrogen atmosphere to obtain Leucovorin Calcium with 0.31 ppm Lead content. The resulting product was purified again with montmorillonite to give Leucovorin Calcium with 0.03 ppm Lead content.

[0223] Heavy metal content in the crude and purified product is presented below:

[0224] Example 7: Purification of calcium saccharate tetrahydrate

[0225] Mono potassium D-saccharate (8.0 g) was mixed with demineralized water (40.0 mL) and heated to 35-40°C. The mixture was stirred for 10 minutes at this temperature to obtain a suspension. Potassium hydroxide dissolved in water (16 mL) was added to the suspension to obtain a clear solution at 35-40°C to maintain pH of 7.3. Activated charcoal (0.2 g) was added at 35-40°C, followed by Montmorillonite K10 (0.32 g) at the same temperature. The slurry was stirred at 35-40°C for 60 minutes.

[0226] The solution was filtered through a celite bed. The celite bed assembly was rinsed with water (8 mL). The combined filtrate and washings were added into a reactor and heated to maintain a temperature of 35-40°C. A 5 pm filtered calcium chloride solution was added at 35-40°C. The mixture was stirred for 2 hours at same temperature. The slurry was filtered using 5 pm filter aid, and washed with 5 pm filtered DM water (8 mL), and suction dried for 10 minutes to obtain a solid. FK24211-03-PAT-WO

[0227] The solid was resuspended in 5 pm filtered DM water (40 mL), and stirred for 1 hour at 20- 30°C, filtered, washed with 5 pm filtered DM water (8 mL), suction dried for 10 minutes, and finally dried under vacuum at 30-35°C for 16 hours.

[0228] Heavy metal content in the crude and purified product is presented below

[0229] Example 8: Purification of calcium saccharate tetrahydrate

[0230] Mono potassium D-saccharate (10.0 g) was mixed with demineralized water (50.0 mL) and heated to 35-40°C. The mixture was stirred for 5-10 minutes at this temperature to obtain a suspension. Potassium hydroxide dissolved in water (20 mL) was added to the suspension at 35-40°C to adjust pH to 6.9. The mixture was stirred for 30 minutes at 35-40°C.

[0231] Activated charcoal (0.2 g) and Montmorillonite K10 (0.32 g, 4.0% w / w) were added at 35- 40°C, and the slurry was stirred for 60 minutes. The hot solution was filtered through a celite bed and rinsed with water (8.0 mL). The combined filtrate and washings were filtered through a 0.22 pm filter and rinsed with 4.0 mL water.

[0232] The combined filtrate and washing were heated to 35-40°C. A 0.22 pm filtered calcium chloride solution was added at 35-40°C, and the mixture was stirred for 3 hours at this temperature. The resulting slurry was filtered under vacuum using 5 pm filter, and the solid was washed with 0.22 pm filtered water (8 mL) and suction dried for 45 minutes.

[0233] The solid was resuspended in 0.22 pm filtered water (40 mL), heated to 55-60°C, and stirred for 4 hours. The slurry was filtered under vacuum using 5 pm filter, washed with 0.22 pm filtered water (8 mL), and suction dried for 30 minutes. This washing and drying cycle was repeated once more. The final solid was dried under vacuum at 35-40°C for 15 hours. FK24211-03-PAT-WO

[0234] Heavy metal content in the crude and purified product is presented below

Claims

FK24211-03-PAT-WOWe claim:

1. A process for the purification of an API by reducing heavy metal content, comprising the steps of: a) mixing the API, which contains heavy metal, and a liquid medium; b) treating the mixture of step a) with montmorillonite; and c) isolating the purified API.

2. The process of claim 1 , wherein the API contains one or more heavy metals selected from the group consisting of iron, nickel, palladium, chromium, aluminium, and lead.

3. The process of claim 1 or claim 2, wherein the API is selected from the group consisting of 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt, Carfilzomib, Calcium saccharate tetrahydrate and Leucovorin Calcium.

4. The process of claim 3, wherein API is 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt.

5. The process of claim 4, wherein the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt contains: a) an iron metal content not exceeding 10.0 ppm, preferably not exceeding 4.0 ppm, more preferably is substantially free from iron metal content, and / or b) a palladium metal content not exceeding 20.0 ppm, preferably not exceeding 17.0 ppm, more preferably is substantially free from palladium metal content, and / or c) a nickel metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably is substantially free from nickel metal content, and / or d) a chromium metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably is substantially free from chromium metal content.

6. The process of claim 3, wherein the API is Carfilzomib.

7. The process of claim 6, wherein the purified Carfilzomib contains: a) a nickel metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably is substantially free from nickel metal content, and / orFK24211-03-PAT-WO b) a palladium metal content not exceeding 30.0 ppm, preferably not exceeding 28.0 ppm, more preferably is substantially free from palladium metal content, and / or c) an iron metal content not exceeding 30.0 ppm, preferably not exceeding 26.0 ppm, more preferably is substantially free from iron metal content, and / or d) a chromium metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably is substantially free from chromium metal content.

8. The process of claim 1 , wherein in step a) API is potassium saccharate.

9. The process of claim 8, wherein after step b) the process involves adding a salt-forming agent.

10. The process of claim 9, wherein the salt-forming agent is calcium chloride.

11. The process of claim 3, wherein purified API is Calcium saccharate tetrahydrate.

12. The process of claim 8, wherein the purified Calcium saccharate tetrahydrate contains: a) an aluminium metal content not exceeding 50.0 ppm, preferably not exceeding 48.0 ppm, more preferably is substantially free from aluminium metal content, and / or b) a nickel metal content not exceeding 40.0 ppm, preferably not exceeding 35.0 ppm, more preferably is substantially free from nickel metal content.

13. The process of claim 3, wherein the API is Leucovorin Calcium.

14. The process of claim 13, wherein the purified Leucovorin Calcium contains a lead metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Leucovorin Calcium is substantially free from lead metal.

15. The process of any preceding claim, wherein the liquid medium is selected from the group consisting of water, alcohol, halogenated solvent, aliphatic hydrocarbon, and polar aprotic solvent or a mixture thereof, preferably the liquid medium is selected from the group consisting of water, methanol, ethanol, propanol, dichloromethane, dichloroethane, n-heptane, n-hexane, and acetone or mixture thereof, more preferably the liquid medium is selected from the group consisting of water, methanol, dichloromethane, n-heptane and acetone or a mixture thereof.FK24211-03-PAT-WO16. The process of any preceding claim, wherein the mixture is provided at a temperature in the range of 15-55°C, preferably in the range of 20-45°C, more preferably in the range of 25-40°C.

17. Purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt: a) containing an iron metal content not exceeding 10.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt is substantially free from iron metal content, and / or b) containing a palladium metal content not exceeding 20.0 ppm, preferably not exceeding 17.0 ppm, more preferably the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from palladium metal content, and / or c) containing a nickel metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2-carboxyethyl)thio-y- cyclodextrin sodium salt is substantially free from nickel metal content, and / or d) containing a chromium metal content not exceeding 2.0 ppm, preferably not exceeding 1.0 ppm, more preferably the purified 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt is substantially free from chromium metal content.

18. Purified Carfilzomib: a) containing a nickel metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from nickel metal content, and / or b) containing a palladium metal content not exceeding 30.0 ppm, preferably not exceeding 28.0 ppm, more preferably the purified Carfilzomib is substantially free from palladium metal content, and / or c) containing an iron metal content not exceeding 30.0 ppm, preferably not exceeding 26.0 ppm, more preferably the purified Carfilzomib is substantially free from iron metal content, and / orFK24211-03-PAT-WO d) containing a chromium metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Carfilzomib is substantially free from chromium metal content.

19. Purified Calcium saccharate tetrahydrate: a) containing an aluminium metal content not exceeding 50.0 ppm, preferably not exceeding 48.0 ppm, more preferably the purified Calcium saccharate tetrahydrate is substantially free from aluminium metal content, and / or b) containing a nickel metal content not exceeding 40.0 ppm, preferably not exceeding 35.0 ppm, more preferably the purified Calcium saccharate tetrahydrate is substantially free from nickel metal content.

20. Purified Leucovorin Calcium containing a lead metal content not exceeding 5.0 ppm, preferably not exceeding 4.0 ppm, more preferably the purified Leucovorin Calcium is substantially free from lead metal content.

21. Use of montmorillonite for the purification of an API by reducing heavy metal, which are preferably selected from the group consisting of iron, nickel, palladium, chromium, aluminium, and lead.

22. A purified API selected from the group consisting of 6-perdeoxy-6-per(2- carboxyethyl)thio-y-cyclodextrin sodium salt, Carfilzomib, Calcium saccharate tetrahydrate and Leucovorin Calcium, obtainable by the process according to any one of claims 1, 2, 15 or 16.

23. A pharmaceutical composition comprising a purified API selected from the group consisting of 6-perdeoxy-6-per(2-carboxyethyl)thio-y-cyclodextrin sodium salt, Carfilzomib, Calcium saccharate tetrahydrate, and Leucovorin Calcium, together with one or more pharmaceutically acceptable excipients.

24. A process for the purification of saccharate by reducing heavy metal content, comprising the steps of: a) mixing potassium saccharate, which contains heavy metal, and a liquid medium; b) treating the mixture of step a) with montmorillonite;FK24211-03-PAT-WO c) adding a salt-forming agent to the mixture obtained in step b), wherein the saltforming agent is calcium chloride; and d) isolating calcium saccharate in which the saccharate is purified from heavy metals.Vishal Sudan (IN / PA / 2390)(Agent of the Applicant - Fresenius Kabi Oncology Ltd.) Head of Department - Intellectual Property ManagementFresenius Kabi Business Services India Pvt Ltd

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