Stable parenteral formulations of cetrorex acetate

Abstract

This invention relates to a stable parenteral dosage form having a sterile, stable aqueous solution of cetrorelix acetate for immediate injection. The invention also relates to an injection device pre-filled with a sterile, stable aqueous solution of cetrorelix acetate for immediate injection. This invention relates to a method for inhibiting premature luteinizing hormone surges in women undergoing controlled ovarian stimulation, comprising a stable parenteral dosage form having a sterile, stable aqueous solution of cetrorelix acetate for immediate injection.

Description

Technical Field

[0001] This invention relates to a stable parenteral dosage form comprising a ready-to-inject, sterile, stable aqueous solution of cetrorelix acetate. The invention also relates to an injection device pre-filled with a ready-to-inject, sterile, stable aqueous solution of cetrorelix acetate. This invention relates to a method for inhibiting premature luteinizing hormone surges in women undergoing controlled ovarian stimulation, comprising a stable parenteral dosage form comprising a ready-to-inject, sterile, stable aqueous solution of cetrorelix acetate. Background Technology

[0002] Cetrorexate is a gonadotropin-releasing hormone antagonist (GnRH antagonist) with the following formula: acetyl-D-3-(2′-naphthyl)-alanine-D-4-chlorophenylalanine-D-3-(3′-pyridyl)-alanine-L-serine-L-tyrosine-D-citrulline-L-leucine-L-arginine-L-proline-D-alanine-amide (C70H92ClN17O14). It is a decapeptide with a terminal acid amide group. It works by blocking the action of GnRH on the pituitary gland, thus rapidly inhibiting the production and action of luteinizing hormone and follicle-stimulating hormone.

[0003]

[0004] For parenteral administration, an aqueous solution of peptides is required. However, aqueous solutions of peptides such as cetrirexate are susceptible to chemical degradation. They are also prone to aggregation, which increases the turbidity or cloudiness of the solution during storage.

[0005] The first product on the market was It is available as a lyophilized powder in glass vials containing 0.25 mg or 3 mg of cetrirexate. Pre-filled glass syringes with 1 ml or 3 ml of sterile water for injection are provided, and the solution is prepared only prior to injection. Thus, the first product simply solves the degradation problem in aqueous solution by avoiding the preparation of dosage forms containing aqueous solutions that need to be stored over time. Instead, water is removed and the lyophilized product is prepared to avoid instability problems. However, this solution to the problem has significant drawbacks - (1) an expensive and time-consuming process; (2) the product is not an immediate injectable form and needs to be reconstituted before administration; and (3) the reconstituted solution is stable only for a short period of time. Therefore, This does not meet the demand for instant-injection aqueous solutions.

[0006] US 7,718,599 discloses that aqueous solutions of cetrorelix readily aggregate. A liquid crystalline structure was observed under polarized light microscopy. Adding gluconic acid to a cetrorelix acetate solution (2.5 mg / ml), resulting in a pH of less than 0.07% gluconic acid at 3.7, resulted in aggregates observed within 2 days. Similar failures were reported when the pH was greater than 3.7. When the gluconic acid concentration was increased to 0.71%, resulting in a pH of 3.1, aggregates were observed within 12 days, indicating that higher concentrations of gluconic acid and therefore lower pH led to improvement. A drawback of this method is that the degree to which the aggregate problem is resolved depends on the gluconic acid concentration, and with more gluconic acid, the pH decreases. However, US 7,718,599 does not report the effect of pH on the chemical stability of cetrorelix. Furthermore, no formulation was found that did not exhibit aggregates during long-term storage stability studies. US2013 / 0303464 discloses a ready-to-use aqueous formulation of cetrorelix comprising cetrorelix acetate, glacial acetic acid, a tension adjuster, and water for injection. A suitable pH is demonstrated through a working example in which the pH is about 3. A preferred pH according to the invention is pH 2.8 to 3.5.

[0007] US 7,214,662 discloses an aqueous solution of a peptide comprising cetrorex acetate and a proposed solution for the problem of aggregation. It teaches that a combination of a carboxylic acid (and particularly a hydroxycarboxylic acid, preferably gluconic acid) with a surfactant reduces aggregation. The use of a carboxylic acid according to US 7,214,662 results in a low pH, for example, pH 2.5 to 3. Detailed Implementation

[0008] The object of this invention is to provide a parenteral dosage form comprising a sterile, stable aqueous solution of cetrorelix acetate for immediate injection. Another object of this invention is to provide an injection device pre-filled with a sterile, stable aqueous solution of cetrorelix acetate. As used herein, the term "immediate injection" refers to a sterile, stable aqueous solution of cetrorelix acetate for immediate injection, suitable for direct subcutaneous or intramuscular administration; that is, it is immediate injection and does not require reconstitution or dilution prior to injection. More specifically, another object is that the sterile, stable aqueous solution of cetrorelix acetate dispensed in the injection device is immediate injection-grade, physically stable not only in terms of control over aggregation or turbidity development but also chemically stable, such that impurities remain low when the parenteral dosage form is stored on the shelf and until it is injected subcutaneously or intramuscularly into a patient.

[0009] The degradation of peptides can lead to the formation of other peptides and / or peptide derivatives, which themselves may possess pharmacological activity. Therefore, more specifically, the aim is to develop a suitable method to separate and quantify individual impurities. The aim is to limit the concentration of such impurities. The inventors have discovered a high-performance liquid chromatography (“HPLC”) method that yields individual peaks for several impurities not previously reported in the art. While the prior art claims that lower pH values ​​reduce the tendency for aggregation, the inventors have found, using their HPLC method, that a pH of 3 to 5 is optimal for chemical stability in the parenteral dosage forms of the present invention in terms of the increase in impurity levels over a period of time, and that aqueous solutions of cetrorex acetate can be prepared at such higher pH values ​​without aggregation problems.

[0010] The inventors have discovered a novel impurity, impurity A, represented by a compound of formula I given below:

[0011]

[0012] Impurity B is characterized by having a structure represented by the compound of formula II given below:

[0013]

[0014] Impurity D is characterized by having a structure represented by the compound of formula III given below:

[0015]

[0016] Impurity F is characterized by having a structure represented by the compound of formula IV given below:

[0017]

[0018] The prior art considers a low pH of 3.0 to be the optimal pH for stability; however, the present invention has found that at pH values ​​of 2.5 to 3.0 recommended by the prior art, the level of impurity A increases significantly when the solution is stored at 25°C / 60% relative humidity.

[0019] No compounds of formulas I, II, III and IV have been identified by existing technologies; these are impurities A, B, D and F, respectively.

[0020] This invention reveals that not only can stable aqueous solutions of cetrorex acetate be prepared at pH 3-5 without coagulation problems, but the levels of impurity A and total impurities are also well controlled, and the parenteral formulation maintains a low concentration after storage at 25°C / 60% RH for at least 1 month, at least 2 months, at least 3 months, or at least 6 months. The parenteral formulation can also be stored with good stability at 2°C to 8°C for at least 24 months.

[0021] In one aspect, the present invention provides a parenteral dosage form comprising a stable aqueous solution, comprising:

[0022] (i) cetrorex or a pharmaceutically acceptable salt thereof; and

[0023] (ii) Impurities of Formula I, less than 5% w / v of cetrorex base.

[0024]

[0025] Preferably, the parenteral dosage form contains less than 4% w / v cetrorexate as an impurity of Formula I. More preferably, the parenteral dosage form contains less than 3% w / v cetrorexate as an impurity of Formula I. More preferably, the parenteral dosage form contains less than 2% w / v cetrorexate as an impurity of Formula I. More preferably, the parenteral dosage form contains less than 1% w / v cetrorexate as an impurity of Formula I.

[0026] Parenteral dosage forms further include penetrants and water for injection.

[0027] In a preferred aspect, the present invention provides a parenteral dosage form comprising a stable aqueous solution, comprising:

[0028] (i) cetrorex or a pharmaceutically acceptable salt thereof; and

[0029] (ii) Impurities of Formula I in amounts less than 1% w / v of cetrirexate.

[0030]

[0031] In another aspect, the present invention provides a parenteral dosage form comprising a stable aqueous solution, comprising:

[0032] (i) cetrorex or a pharmaceutically acceptable salt thereof; and

[0033] (ii) Impurities of Formula I in amounts less than 1% w / v of cetrirexate.

[0034]

[0035] In another aspect, the present invention provides a parenteral dosage form comprising an injectable, sterile, stable aqueous solution, comprising:

[0036] (i) Cetrolec or its pharmaceutically acceptable salt.

[0037] (ii) Organic acids with pH adjusted to the range of 3 to 5.

[0038] (iii) Impurity A, a decapeptide of formula I, in amounts less than 1% w / v of cetrilac base.

[0039]

[0040] (iv) Penetrants; and

[0041] (v) Water for injection.

[0042] In one embodiment, the present invention provides a parenteral dosage form comprising an injectable, sterile, stable aqueous solution, which is composed of the following:

[0043] (i) Cetrolec or its pharmaceutically acceptable salt.

[0044] (ii) Organic acids with pH adjusted to the range of 3 to 5.

[0045] (iii) Impurity A, a decapeptide of formula I, in amounts less than 1% w / v of cetrilac base.

[0046]

[0047] (iv) Penetrants, and

[0048] (v) Water for injection.

[0049] When stored at 2°C to 8°C for at least 1 month, at least 3 months, at least 6 months, at least 12 months, at least 18 months, or at least 24 months; or at room temperature (25°C / 60% RH) for at least 1 month, at least 3 months, or at least 6 months, the parenteral dosage form containing cetrorex according to the invention remains physically and chemically stable.

[0050] Preferred embodiments of stable parenteral dosage forms may be labeled with a shelf life of at least 24 months at 2°C to 8°C. More preferred embodiments of parenteral dosage forms may be labeled with a shelf life of at least 6 months at room temperature (25°C / 60% RH).

[0051] When stored at 2°C to 8°C for at least 1 month, at least 2 months, at least 3 months, at least 6 months, at least 12 months, at least 18 months, or at least 24 months and / or at room temperature (25°C / 60% RH) for at least 1 month, at least 2 months, at least 3 months, or at least 6 months, the concentration of the decapeptide of Formula I (impurity A) is maintained in the range of 0.001% by weight to 1.0% by weight, preferably 0.05% by weight to 0.5% by weight, of cetrorexine; the single largest unknown impurity is maintained at less than 0.5% by weight of cetrorexine; and the total impurities are maintained at no more than 3.5% by weight of cetrorexine.

[0052] The parenteral dosage form of cetrorex, a sterile aqueous solution for immediate injection according to the invention, is physically stable, and the aqueous solution does not aggregate, gel, or precipitate during its shelf life. Aggregation or gel formation can be determined by measuring the turbidity or turbidity of the solution. It is measured in FTU units (Formazin turbidity units) or NTU units (Nephelometric Turbidity Units).

[0053] The test was conducted according to the protocol described in European Pharmacopoeia 9.0. If the turbidity / cloudiness value is less than or equal to 8 FTU / NTU, the solution is considered to have no aggregation or gel formation. A higher FTU / NTU value indicates higher turbidity or cloudiness in the solution, and vice versa. The NTU value of the immediate-injection parenteral dosage form according to the invention remains less than 2 NTU initially and after prolonged storage at 2°C to 8°C for at least 1 month, at least 2 months, at least 3 months, at least 6 months, at least 12 months, at least 18 months, or at least 24 months and / or at room temperature (25°C / 60% RH) for at least 6 months, preferably less than 1 NTU, more preferably less than 0.5 NTU. Therefore, no aggregation, gel formation, or precipitation of the aqueous solution occurs during the shelf life. Furthermore, the viscosity of the solution does not increase significantly during storage.

[0054] A parenteral dosage form comprising an immediate-injection, sterile, stable aqueous solution of cetrorex according to the invention comprises cetrorex acetate at a concentration ranging from 0.26 mg / ml to 0.28 mg / ml, which is equivalent to 0.25 mg / ml of cetrorex base. Preferably, cetrorex acetate is present in the immediate-injection, sterile, stable aqueous solution at a concentration equivalent to 0.25 mg / ml of cetrorex base.

[0055] In one embodiment, a parenteral dosage form comprising an immediate-injection, sterile, stable aqueous solution of cetrorex according to the invention contains a pH adjuster at a concentration sufficient to adjust the pH in the range of 3 to 6.

[0056] In a preferred embodiment, the parenteral dosage form comprising an immediate-injection, sterile, stable aqueous solution of cetrorex according to the invention contains an organic acid as a pH adjuster, at a concentration sufficient to adjust the pH to a range of 3 to 5, more preferably in the range of 4 to 4.5. The pH of the immediate-injection, sterile, stable aqueous solution according to the invention can be, for example, 3, 3.05, 3.10, 3.15, 3.20, 3.25, 3.30, 3.35, 3.40, 3.45, 3.5, 3.55, 3.60, 3.65, 3.70, 3.75, 3.80, 3.85, 3.90, 3.95, 4.00, 4.05, 4.10, 4.15. 4.20, 4.25, 4.30, 4.35, 4.40, 4.45, 4.50, 4.55, 4.60, 4.65, 4.70, 4.75, 4.80, 4.85, 4.90, 4.95, 5.00, 5.05, 5.10, 5.15, 5.20, 5.25, 5.30, 5.35, 5.40, 5.45, 5.50, 5.55 and 6 or a range thereof.

[0057] The organic acid may be selected from any water-soluble, parenteral-acceptable organic acid, but preferably acetic acid, more preferably lactic acid. For example, lactic acid may be used in the sterile aqueous solution of the immediate-injection type according to the invention in an amount ranging from about 0.013 mg / ml to 0.53 mg / ml, preferably in a concentration ranging from about 0.033 mg / ml to about 0.53 mg / ml, and intermediate concentrations thereof.

[0058] Preferably, according to the present invention, the sterile, stable aqueous solution of cetrorex for immediate injection contains cetrorex (base) and an organic acid in a weight ratio ranging from 50.47:1 to 19.23:1, preferably from about 0.47:1 to 7.57:1, and more preferably from about 1.56:1 to 7.57:1 and intermediate ranges.

[0059] The parenteral dosage form of cetrorelict, a sterile, stable aqueous solution for immediate injection according to the invention, contains an osmotic agent or tonic modifier in an amount suitable for adjusting the osmotic concentration of the solution to about 250-375 mOsm / kg, preferably 270-330 mOsm / kg. The osmotic agent that can be used in the aqueous solution according to the invention is selected from, but is not limited to, mannitol, glycerol, sorbitol, sodium chloride, potassium chloride, dextrose, sucrose, and mixtures thereof.

[0060] According to a preferred embodiment, the penetrant is mannitol, and it can be used in an aqueous solution at a concentration ranging from about 40.0 mg / ml to 60.0 mg / ml, preferably from about 50.0 mg / ml to 58.0 mg / ml. In a preferred embodiment, the penetrant is mannitol, and it is used in a sterile aqueous solution for immediate injection at a concentration of about 55.0 mg / ml.

[0061] The parenteral dosage form of the present invention, an immediate-injection, sterile aqueous solution, does not contain lactic acid in the form of its derivatives, polymers, or copolymers, such as polylactic acid or polylactic-co-glycolic acid. Preferably, lactic acid is used as the sole pH adjuster. In preferred embodiments, the immediate-injection, sterile aqueous solution is free of any surfactants, such as Tween 80, polysorbate, poloxamer, Span, etc. The immediate-injection, sterile aqueous solution of the parenteral dosage form avoids the use of surfactants, complexing agents, preservatives, or antioxidants for dissolution or stabilization. In some embodiments, the solution is free of complexing agents such as cyclodextrins, cosolvents such as alcohols or glycols, and also free of preservatives and antioxidants.

[0062] In another aspect, the present invention provides a sterile aqueous solution of cetrorex acetate as described above, which remains stable at 25°C and 60% relative humidity for at least one month, preferably at least three months, and more preferably at least six months.

[0063] In another aspect, the present invention provides a sterile aqueous solution of cetrorex acetate as described above, which remains stable at 2-8°C for at least 1 month, preferably at least 3 months, more preferably at least 6 months, even more preferably at least 12 or 18 months, and most preferably at least 24 months.

[0064] A stable parenteral dosage form comprising an immediate-injection, sterile, stable aqueous solution of cetrorex according to the invention is suitable for administration via subcutaneous or intramuscular routes. The immediate-injection, sterile, stable aqueous solution is suitable for direct subcutaneous administration, i.e., it is an immediate-injection or immediate self-administration formulation and does not require reconstitution or dilution prior to use. The immediate-injection, sterile, stable aqueous solution according to the invention does not involve lyophilization.

[0065] The stable parenteral dosage form of the present invention is suitable for self-administration and allows patients to subcutaneously self-administer small amounts of the aqueous solution. The volume of the sterile, injectable aqueous solution of cetrorelix in the reservoir of the injection device ranges from about 0.5 ml to 10.0 ml, preferably from 1.0 ml to 2.0 ml, more preferably 1.0 ml. According to one preferred embodiment, the sterile, stable, injectable aqueous solution of cetrorelix is ​​filled in the reservoir of the injection device in a volume of 1.0 ml. Preferably, the parenteral dosage form according to the present invention is suitable for administering a single dose of cetrorelix acetate. In one embodiment, the parenteral dosage form comprises an aqueous solution of cetrorelix acetate in a fill volume of about 1.0 ml suitable for single-dose self-administration. In some embodiments, the parenteral dosage form may comprise an aqueous solution of cetrorelix acetate in a fill volume of about 10.0 ml, which is suitable for multiple-dose administration.

[0066] The injection device for the stable parenteral dosage form according to the present invention can be selected from, but is not limited to, pre-filled syringes, autoinjectors, etc. In a preferred embodiment, the injection device is a pre-filled syringe. In another preferred embodiment, the injection device is an autoinjector, such as a pen-type autoinjector. These pre-filled syringes or autoinjectors are suitable for self-administration or automated injection of drug solutions by patients in need, thus providing a user-friendly method.

[0067] In a preferred embodiment, the injection device is a pre-filled syringe. The pre-filled syringe comprises: a reservoir for storing an aqueous solution, such as, for example, a bucket or tube; a shank needle attached to one end of the reservoir; a needle guard or needle tip cap covering the needle and sealing the needle tip opening, optionally a rigid guard covering the needle guard or needle tip cap; a plunger stopper located at the other end of the reservoir, which plugs and seals the aqueous solution filled in the reservoir; and a plunger rod fitted into the plunger stopper and used to push the plunger stopper, along with the solution, toward the needle tip during administration of the drug.

[0068] In another preferred embodiment, the injection device is an autoinjector. The autoinjector can have varying designs. In a preferred design, the autoinjector includes a central assembly or body portion adapted to hold a pre-filled syringe, the syringe containing a reservoir, such as a bucket or canister, for storing an aqueous solution, the reservoir having a shank needle at one end and a plunger stopper at the other end. The central body portion may have a transparent inspection window through which the solution in the reservoir is visible. The autoinjector further includes a front assembly having a cap portion that receives a needle guard or needle tip cap and is attachable to the central assembly that covers the shank needle and seals the needle tip opening. The autoinjector further includes a rear assembly containing a plastic rod with a spring assembly and an activation button. During self-administration of the aqueous solution, firstly, the cap, along with the needle guard, is removed from the body portion to expose the needle, and then, after placing the body portion of the autoinjector at the administration site, the activation button is pressed, which pushes the plastic rod with the spring assembly against the plunger stopper, causing the aqueous solution to be delivered to the patient through the needle.

[0069] The reservoir can be a bucket or tube, such as, for example, the bucket of a pre-filled syringe or the tube of an autoinjector. It can be made of a material selected from glass, plastics, or polymeric materials. In some preferred embodiments, the reservoir is made of glass, such as USPI-type siliconized glass or a non-suppurative glass material. In other embodiments, the reservoir is made of a non-glass plastic or polymeric material selected from cyclic olefin polymers, cyclic olefin copolymers, polyolefin polycarbonates, styrene-polyolefin-based polymers and block copolymers, polycarbonates, etc. In a preferred embodiment, the reservoir is a non-suppurative glass bucket of a pre-filled syringe or a non-suppurative glass tube of an autoinjector.

[0070] In one or more embodiments, the reservoir may have a stacked needle at one end. In some other embodiments, the reservoir is needleless and has a Luer tip lock at one end with means for attaching the needle to the Luer tip before use. The shank needle may be made of stainless steel. The needle tip is shielded or covered by a needle guard or needle tip cap. The reservoir containing a sterile aqueous solution of the drug is further sealed at the other end with a stopper, such as a plunger stopper. These stoppers, needle guards, or needle tip caps provide a physical and sterile barrier to the external environment.

[0071] Preferably, the plunger stopper, needle guard / tip cap, or Luer lock cap is made of a non-glass component. The non-glass component can be a rubber or elastomeric material, such as, for example, bromobutyl rubber, chlorobutyl rubber, USP Type II rubber, natural rubber composed of poly(cis-1,4-isoprene), styrene-butadiene rubber, etc. Other suitable materials include high-density polyethylene or low-density polyethylene or other plastic materials. In a preferred embodiment, the plunger stopper is made of bromobutyl rubber, and the needle guard or tip cap is made of natural rubber. The needle guard may be further covered externally by a rigid shield made of polypropylene. This protects the needle guard from damage and enhances its removal before injection. The injection device assembly may have a plunger rod connected to the plunger stopper and used to push the plunger stopper, along with the solution, towards the needle tip during drug administration.

[0072] Preferably, a sterile, stable, instant-injectable aqueous solution of cetrilac is filled into the reservoir of the injection device and stoppered in a manner that leaves substantially no air in the headspace inside the reservoir. During storage, the aqueous solution in the reservoir remains in contact with the plunger stopper, which is made of an elastomeric or rubber material. In the case of a pre-filled syringe with a shank needle made of stainless steel, the needle is covered by a needle guard or needle cap, and the aqueous solution remains in contact with the needle and the needle guard or needle cap during storage.

[0073] The injection device can optionally be packaged or sealed in a secondary packaging. The secondary packaging can be blister packs, aluminum bags, and / or opaque cardboard boxes. A suitable oxygen scavenger can optionally be placed inside the secondary packaging.

[0074] Stability testing of the parenteral dosage form was performed by storing the dosage form at 2-8°C and room temperature (25°C / 60% relative humidity). During the stability test, the sterile solution of cetrorex for immediate injection remained in contact with a plunger stopper and needle guard made of elastomeric rubber material and with a stack of needles made of stainless steel. In a preferred embodiment, the parenteral dosage form containing a sterile aqueous solution of cetrorex for immediate injection according to the invention remained physically and chemically stable for a period of 1 year, preferably 2 years, when stored at 2-8°C and for at least 6 months when stored at room temperature (25°C, 60% relative humidity). When the filled injection device was stored at room temperature (25°C / 60% relative humidity) for at least 6 months and at 2-8°C for at least 24 months, the concentration of impurity A remained less than 1.0% by weight of cetrorex base. The extrapolated shelf life of cetrirexy aqueous solution with impurity A levels not exceeding 1%, as determined by Minitab calculations, is 122 months.

[0075] In one aspect, the present invention relates to a method for inhibiting premature luteinizing hormone surges in women undergoing controlled ovarian stimulation, comprising:

[0076] A parenteral dosage form comprising: a sterile, stable aqueous solution for immediate injection, comprising:

[0077] (i) cetrorex or a pharmaceutically acceptable salt thereof; and

[0078] (ii) Impurities of Formula I, less than 5% w / v of cetrorex base.

[0079]

[0080] Preferably, the stable aqueous solution contains less than 4% w / v of cetrorexate as an impurity of Formula I. More preferably, the stable aqueous solution contains less than 3% w / v of cetrorexate as an impurity of Formula I. More preferably, the stable aqueous solution contains less than 2% w / v of cetrorexate as an impurity of Formula I. More preferably, the stable aqueous solution contains less than 1% w / v of cetrorexate as an impurity of Formula I.

[0081] The stable aqueous solution further contains a penetrant and water for injection.

[0082] In one aspect, the present invention relates to a method for inhibiting premature luteinizing hormone surges in women undergoing controlled ovarian stimulation, comprising:

[0083] A parenteral dosage form comprising: a sterile, stable aqueous solution for immediate injection, comprising:

[0084] (i) Cetrolec or a pharmaceutically acceptable salt thereof;

[0085] (ii) Impurity A, a decapeptide of formula I, in amounts less than 1% w / v of cetrorexine.

[0086]

[0087] In one aspect, the present invention relates to a method for inhibiting premature luteinizing hormone surges in women undergoing controlled ovarian stimulation, comprising: a parenteral dosage form comprising: a sterile, stable aqueous solution for immediate injection, comprising:

[0088] (i) Cetrolec or a pharmaceutically acceptable salt thereof;

[0089] (ii) Impurity A, a decapeptide of formula I, in amounts less than 1% w / v of cetrorexine.

[0090]

[0091] In a preferred aspect, the present invention relates to a method for inhibiting premature luteinizing hormone surges in women undergoing controlled ovarian stimulation, comprising: a parenteral dosage form comprising: an injectable, sterile, stable aqueous solution containing:

[0092] (i) Cetrolec or its pharmaceutically acceptable salt.

[0093] (ii) Organic acids with pH adjusted to the range of 3 to 5.

[0094] (iii) Impurity A, a decapeptide of formula I, in amounts less than 1% w / v of cetrorexine.

[0095]

[0096] (iv) Penetrants, and

[0097] (v) Water for injection.

[0098] In another aspect, this disclosure provides a decapeptide of formula I.

[0099]

[0100] This compound is referred to as "Impurity A" in this paper because it is an impurity in cetrilac solution.

[0101] This disclosure also provides a composition comprising a decapeptide of formula I:

[0102]

[0103] In another aspect, this disclosure provides a process for identifying decapeptides of Formula I by HPLC analysis, the process comprising:

[0104] a) Inject a diluent containing water, acetonitrile, and formic acid into the chromatographic system.

[0105] b) Inject a system suitability solution containing cetrorex acetate, diluent, and impurity stock solution, and record the chromatogram.

[0106] c) Inject a standard solution containing cetrorex acetate and a diluent into the chromatographic system.

[0107] d) Inject the sample containing an aqueous solution of cetrorex acetate and a placebo formulation into the chromatographic system, and

[0108] e) Determine the relative retention time and relative response factor of impurities and cetrorex acetate relative to cetrorex acetate.

[0109] This disclosure also provides a decapeptide of formula I identified by HPLC analysis, the process comprising:

[0110] 1. Inject a diluent containing water, acetonitrile, and formic acid into the chromatographic system.

[0111] 2. Inject a system suitability solution containing cetrorex acetate, diluent, and impurity stock solution, and record the chromatogram.

[0112] 3. Inject a standard solution containing cetrorex acetate and a diluent into the chromatographic system.

[0113] 4. Inject the sample containing an aqueous solution of cetrorex acetate and a placebo formulation into the chromatographic system, and...

[0114] 5. Determine the relative retention time and relative response factor of the impurities and citrorex acetate relative to citrorex acetate.

[0115] In the following description, the invention will be illustrated in more detail by way of examples. These examples are not intended to limit the scope of the invention and are merely illustrative.

[0116] Example 1A Identification of degradation products

[0117] To investigate the degradation of cetrorex, peptide-related substances of cetrorex were prepared using known techniques of solid-phase peptide synthesis. The synthesis involved coupling one amino acid at a time, starting from the C-terminal amino acid on the resin. The synthesis of the peptide chain was carried out using N,N′-diisopropylcarbodiimide (DIPC) as the coupling agent, with fluoroenylmethyloxycarboxyl (Fmoc) / tert-butyl (Fmoc / tBu) as the coupling agent. The Fmoc group was removed by treatment with 20% piperidine in dimethylformamide. The peptides formed on the resin were finally cleaved using trifluoroacetic acid to obtain the related substances, which were further purified by reversed-phase high-performance liquid chromatography (RP-HPLC) on a C18 silica column using a gradient of acetonitrile / water containing 0.1% trifluoroacetic acid. The purified peptide-related substances were lyophilized to obtain pure solid form. The structures of these related substances were characterized by proton NMR, carbon NMR, mass spectrometry, and elemental analysis, and they were designated as impurities A, B, D, and F.

[0118] Impurity A:

[0119] Ac-2-D-Nal-4-C1-D-Phe-3--D-Pal-Ser-Tyr-D-Cit-Leu-Arg-Pro-D-Ala-OH (depicting the detailed structure of the compound of formula I),

[0120] Impurity B:

[0121] 2-D-Nal-4-C1-D-Phe-3-D-Pal-Ser-Tyr-D-Cit-leu-Arg-Pro-D-Ala-NH2 (depicted in detail the structure of the compound of formula II),

[0122] Impurity D: Ac-2-D-Nal-4-Cl-D-Phe-3-D-Pal-Ser-Tyr-D-Cit-Leu-OH (depicted as the detailed structure of a compound of formula III), and

[0123] Impurity F:

[0124] Ac-2-D-Nal-4-Cl-D-Phe-3-D-Pal-Ser-Tyr-D-Cit-Leu-Arg-Pro-OH (detailed structure of the compound of formula IV).

[0125] Based on the relative retention times of these compounds, the degradation peaks separated on the HPLC column were identified as these compounds. Details of the HPLC method are provided in Example 1B below:

[0126] Example 1B

[0127] Cetrilac and impurities identified from aqueous samples, namely impurities A, B, D, and F, were separated on a reversed-phase (C-18) column using gradient technology (column: X-Select C18, (150x4.6) mm, 2.5 u (by Waters, Ireland, part number: 186006729)). Quantification was performed by UV spectroscopy at 225 nm. The mobile phase was run at flow rates of 0.7 mL / min and 1.0 mL / min. Chromatogram run time was 150 min.

[0128] Mobile phase details:

[0129] Mobile phase A: a mixture of the following buffer solutions, wherein the ratio of acetonitrile to tetrahydrofuran is (700:280:20), and degassed by acoustic treatment.

[0130] Mobile phase B: a mixture of the following buffer solutions, wherein the ratio of acetonitrile to tetrahydrofuran is (500:480:20), degassed by acoustic treatment.

[0131] Buffer solution: 2.5 g of ammonium dihydrogen phosphate and 0.75 g of sodium 1-octanesulfonate in 1000 ml of water, wherein the pH is adjusted to 8.0 ± 0.05 using triethylamine.

[0132] Diluent: A mixture of water, acetonitrile, and formic acid in a ratio of 700:300:1.

[0133] Table 1: Details of gradient elution

[0134]

[0135] Preparation of stock solutions of impurities :

[0136] Place 3.125 mg each of impurity A, impurity B, impurity D and impurity F in a 50 ml volumetric flask and dissolve them in about 5 ml of diluent by acoustic treatment. Then, use diluent to bring the volume to the required level.

[0137] Preparation of system suitability solutions:

[0138] This was prepared by weighing and transferring approximately 12.5 mg of cetrirexate working standard to a 100 ml volumetric flask, dissolving it in approximately 50 ml of diluent by acoustic treatment, then adding approximately 2 ml of impurity stock solution and making up the volume with diluent.

[0139] Preparation of standard solution of cetrorex acetate:

[0140] The standard solution of cetrorex acetate was prepared by weighing and transferring 20 mg of cetrorex acetate working standard to a 250 ml volumetric flask, dissolving it in approximately 50 ml of diluent by sonication, and then bringing the volume to the mark with diluent. Two ml of this solution was then transferred to a 250 ml volumetric flask and, if mixed, brought to the mark with diluent.

[0141] Preparation of test solution :

[0142] In a container, mix aqueous solutions of cetrorex acetate from approximately 10 pre-filled syringes containing the sample to be tested (prepared according to the example above). The solution contains cetrorex acetate, an organic acid, a penetrant, and water for injection. Accurately transfer approximately 5.0 ml of this solution to a 10 ml volumetric flask, add approximately 3 ml of diluent, and sonicate the solution with intermediate shaking for 5 minutes. Make up the volume with diluent while mixing.

[0143] The placebo was prepared by precisely transferring approximately 5.0 ml of placebo solution to a 10 ml volumetric flask, adding approximately 3 ml of diluent, and sonicating for 5 minutes with intermediate shaking. The volume was then brought to a final volume using diluent while mixing. Two copies of the diluent (50 μL as a blank) were injected into the chromatographic system. Subsequently, the system-suitable solution was injected and the chromatogram was recorded. The resolution between impurity D and impurity F was not less than 2.0. Following this, six replicate standard solutions were injected. Subsequently, the sample and placebo formulations were injected into the chromatographic system.

[0144] Table 2 presents the relative retention times and relative response factors of cetrorex acetate and impurities A, B, D and F relative to cetrorex acetate.

[0145] Table 2:

[0146]

[0147] Calculate the percentages of impurities A, B, D, F, and unknown impurities, excluding peaks from the diluent and placebo. The sum of all known and unknown impurities provides the total impurity percentage.

[0148] The percentage of identified impurities (A, B, D, F) is calculated using the following formula:

[0149]

[0150] in,

[0151] A1 = Peak response of each known impurity in the chromatogram of the test formulation; AS = Average peak response of cetrorex in the chromatogram of the standard formulation; WS = Weight of cetrorex acetate working standard in mg.

[0152] V = Volume of the sample obtained in ml

[0153] P = Potency % of cetrorelix working standard (as is), LC = Label requirement of cetrorelix (0.25 mg / ml) in mg / ml, RRF = Relative response factor for each impurity.

[0154] The percentage of unknown impurities can be calculated using the following formula.

[0155]

[0156] in,

[0157] A1 = Peak response of each unknown impurity in the chromatogram of the test formulation; AS = Average peak response of cetrorex in the chromatogram of the standard formulation; WS = Weight of cetrorex acetate working standard in mg.

[0158] V = Volume of the sample obtained in ml

[0159] P = Potency % of cetrorelix working standard (based on original sample), LC = Label requirements for cetrorelix (0.25 mg / ml) in mg / ml.

[0160] Total impurities (%) = the sum of known impurities % and unknown impurities %

[0161] Table 3: Composition

[0162]

[0163] Preparation method:

[0164] Obtain water for injection in a container at a temperature of 2°C to 8°C. Add mannitol and gradually dissolve it in the water for injection with stirring until a clear solution is obtained. Add cetrilac acetate and gradually dissolve it with stirring. Check the pH of the solution and adjust it to the pH described in Table 3 for each example and comparative example of the invention using a specified volume of 0.1% w / v lactic acid solution. Make up the volume with water for injection. Stir the solution for 10-15 minutes. Aseptically filter the solution of the example through a bed of a 0.2-micron membrane filter. Aseptically fill the reservoir of the injection device, i.e., aseptically fill the barrel of a 1 ml glass syringe with a filling volume of 1.1 ml. The stacked needles in the barrel are plugged with an elastomeric needle guard and covered with a rigid cap before filling. After filling, the glass syringe (barrel) is plugged with a plunger stopper by vacuum plugging, so that there is substantially no residual headspace air in the syringe. During storage, the aqueous solution is kept in contact with a plunger stopper made of rubber, a stacked needle made of stainless steel, and a needle guard made of natural rubber.

[0165] The instant-injectable aqueous solutions of Working Examples 1 to 9 and Comparative Examples 10 to 14 underwent chemical analysis at different stages. Initially, the percentage of cetrirexate in the solution before and after filtration was analyzed by the above-described HPLC method. The changes in the percentage of chemical determination before and after filtration were determined.

[0166] The solution of the example contained in the glass syringe was then subjected to a storage stability test. The levels of the determination % and degradation products (such as compounds of formulas I, II, III, and IV) and the levels of unknown impurities and total impurities in the filtered solution filled in the parenteral dosage form injection device were determined using the above-described high-performance liquid chromatography method.

[0167] After 6 months of storage at room temperature, the levels of impurities A and B, the single largest unknown impurity, and the total impurities remained unchanged or changed only slightly. Based on this data, the parenteral dosage form of the present invention is expected to be chemically stable over a long period of time. No problems of aggregation or increased viscosity were found during the preparation of the solution and during filling into the injection device and storage. The data also confirmed that cetrirex did not absorb or adsorb onto or into any parts of the device, such as the rubber stopper in contact with the solution, during the storage period.

[0168] The stability results of the parenteral dosage forms according to the present invention at 25°C / 60%RH and 2-8°C are provided in Tables 4 and 5 below:

[0169] Table 4:

[0170]

[0171] ND: Not detected; RH - Relative humidity; BQL: Below quantifiable limit.

[0172]

[0173] Table 6:

[0174]

[0175] The stability results for the additional intermediate pH range were investigated at different time points when stored at 25°C / 60% RH and 2–8°C, and are given in Table 7 below:

[0176]

[0177] Table 8:

[0178]

[0179] Table 9:

[0180] Stability data of cetrorex acetate injection at pH 5 for PFS at 0.25 mg / ml and 1 ml.

[0181] Each mL contains cetrorex acetate equivalent to 0.25 mg of cetrorex, 54.8 mg of mannitol, an appropriate amount of lactic acid to adjust the pH to 5.0, and an appropriate amount of water for injection to 1 mL.

[0182]

[0183] ND: Not detected; RH - Relative humidity; BQL: Below quantifiable limit;

[0184] * A clear, colorless solution filled into 1 mL of PFS

[0185]

[0186]

[0187] Comparative Example 2

[0188] An aqueous solution of cetrilac acetate was prepared according to the disclosure in US 2013 / 0303464 (Patel et al.). The composition is shown in Table 12 below:

[0189] Table 12:

[0190] Element Dosage (mg / ml) Cetrilac acetate 0.25 Mannitol 42.0 glacial acetic acid Add appropriate amount to pH 3.0 Water for Injection 1mL

[0191] The preparation method involves obtaining water for injection in a container at a temperature of 2°C to 8°C. Mannitol is added and gradually dissolved in the water for injection with stirring until a clear solution is obtained. Cetrilac acetate is added and gradually dissolved with stirring. Glacial acetic acid is then added, and the pH of the solution is adjusted to approximately 3.0. The volume is made up with water for injection. The solution is stirred for 10–15 minutes and then aseptically filtered through a bed of 0.2 μm membrane filters (Optiscale 47 capsules, via Millipore polyethersulfone membrane filters). The solution is aseptically filled into the reservoir of the injection device, i.e., aseptically filled into the barrel of a 1 ml glass syringe with a filling volume of 1.1 ml. The stacked needles in the barrel are plugged with an elastomeric needle guard and covered with a rigid cap before filling. After filling, the glass syringe (barrel) is sealed with a plunger stopper by vacuum sealing, so that there is essentially no residual headspace air inside the syringe. During storage, the aqueous solution is kept in contact with a plunger stopper made of rubber, a stacked needle made of stainless steel, and a needle guard made of natural rubber.

[0192] The solution of this comparative example (Comparative Example 2), filled in a glass syringe, was subjected to a storage stability test. The levels of impurity A, impurity B, and total impurities in the solution were analyzed using high-performance liquid chromatography (HPLC) initially and during storage at room temperature (25°C / 60% relative humidity). The results are presented in Table 13 below.

[0193] Table 13: Stability results of Comparative Example 2

[0194]

[0195] ND: Not detected; RH - Relative Humidity

[0196] A significant increase in the levels of impurity A and total impurities was observed in the cetrorex acetate solution of US 2013 / 0303464 (comparative) when stored at room temperature. Specifically, the level of impurity A, as a degradation impurity, increased significantly and reached 1.77% by weight of cetrorex within 6 months. The level of total impurities also increased to 2.83% by weight of cetrorex within 6 months.

[0197] In contrast, the parenteral dosage form of the instant-injection aqueous solution of cetrorex acetate of the present invention remains stable at room temperature over an extended period of time, thereby exhibiting substantially no degradation or increase in the levels of impurity A, other impurities, or total impurities during storage, and the solution has an extrapolated shelf life of more than 24 months.

Claims

1. A parenteral dosage form comprising a stable aqueous solution, comprising an injectable, sterile, stable aqueous solution, comprising: (i) 0.25 mg / ml of cetrorex or a pharmaceutically acceptable salt thereof; (ii) Lactic acid at a concentration sufficient to adjust the pH to the range of 4.00 to 5.00; (iii) Impurity A in Formula I, (iv) Penetrants; and (v) Water for injection; After being stored at 25°C and 60% relative humidity for 6 months, the solution contained impurity A in an amount of less than 0.5% w / v cetrilac base.

2. The parenteral dosage form according to claim 1, wherein the penetrant is present in an amount sufficient to give the solution an osmotic concentration in the range of 250 mOsm / Kg to 375 mOsm / Kg.

3. The parenteral dosage form according to claim 1, wherein the immediate-injection type, sterile, stable aqueous solution is present in the reservoir of the injection device.

4. The parenteral dosage form according to claim 3, wherein the injection device is a pre-filled syringe.

5. The parenteral dosage form according to claim 3, wherein the injection device is an auto-injector.

6. The parenteral dosage form according to claim 3, wherein the injection device is a pen-type autoinjector.

7. The parenteral dosage form according to claim 1, wherein the sterile aqueous solution is stable for at least one month at a temperature of 25°C and a relative humidity of 60%.

8. The parenteral dosage form according to claim 1, wherein the sterile aqueous solution is stable for at least 3 months at a temperature of 25°C and a relative humidity of 60%.

9. The parenteral dosage form according to claim 1, wherein the sterile aqueous solution is stable for at least 6 months at a temperature of 25°C and a relative humidity of 60%.

10. The parenteral dosage form according to claim 1, wherein the parenteral dosage form is suitable for subcutaneous use.

11. The parenteral dosage form according to claim 1, wherein the parenteral dosage form is suitable for intramuscular use.

12. Use of the parenteral preparation of any one of claims 1-11 in the preparation of a medicament for inhibiting premature luteinizing hormone surges in women undergoing controlled ovarian stimulation.

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