Polymer-lipid nanocomposites for enhancing aqueous solubility and absorption of hydrophobic active compounds

Abstract

The present invention relates to a polymer-lipid nanocomplex for enhancing the aqueous solubility and absorption of a hydrophobic active compound, a process for producing such nanocomplex and a method of using such nanocomplex.

Description

TECHNICAL FIELD

[0001] The present invention relates to a polymer-lipid nanocomplex for enhancing the aqueous solubilization and absorption of hydrophobic active compounds, a process for producing such nanocomplex and a method of using such nanocomplex. BACKGROUND

[0002] It is estimated that more than 40% of the FDA-approved new chemical entities (NCEs) in the pharmaceutical industry and nearly 90% of the lead compounds entering the development pipeline consist of active compounds that are poorly soluble in water. Among the key physicochemical parameters used in the early screening process of the best drug candidates, poor aqueous solubility or hydrophobicity is a major compound property.

[0003] Poor water solubility of drugs is followed by low permeability, rapid metabolism, extensive protein binding to plasma proteins for elimination from the body, and a large dose-solubility ratio, thus resulting in low bioavailability. Large amounts of drugs are required to reach therapeutic levels, which can lead to poor safety and tolerability, resulting in drug resistance and adverse side effects [1, 2].

[0004] Hydrophobicity of a compound is generally represented by its ability to partition between an organic solvent (octanol) and water, also known as partition coefficient (Log P). Log P values are positive, listed as hydrophobic compounds, and when the value reaches 10, listed as highly hydrophobic, as described in Table 1 proposed by the FDA, which translates to solubility less than 10-4[1]. This is a real challenge for the pharmaceutical industry, as if the active is not solubilized in the gastrointestinal tract (GIT), the active will not reach the target site to exert the intended effect in the body; thus it remains a useless compound. In addition, it is often necessary to ingest a fatty-rich meal to promote the absorption of hydrophobic drugs, resulting in unstable absorption, with large dose-response differences between and within patients.

[0005] Table 1: USP solubility description

[0006]

[0007] Another aspect to always consider in the drug development process is the drug classification given by the Biopharmaceutical Classification System (BCS) in Table 2 [3]. The system uses three drug parameters, including solubility, dissolution, and intestinal permeability, to assist in predicting drug properties. These important parameters will help to achieve the preferred drug concentration in the systemic circulation after oral administration to obtain the desired pharmacological response. Therefore, BCS is an effective tool widely used in the drug development process [3].

[0008] Table 2: Biopharmaceutical Classification System

[0009] Class Solubility Permeability I High High II Low High III High Low IV Low Low

[0010] All these classes of drugs present inherent challenges, Class IV is generally considered outside the so-called "drugable space" but can be overcome by formulation if proven to be effective, overcoming the dual challenges of low solubility and low permeability.

[0011] Several strategies have been used in the pharmaceutical industry to enhance the solubility of drugs. These strategies include: physical modification (e.g. size reduction), chemical modification (e.g. polymer-drug conjugation) and various methods including supercritical fluid micronization. Vimalson et al. [1] have extensively reviewed the various techniques to achieve these modifications. It is worth mentioning that most physical modifications aim to reduce the size, crystallinity and change the morphological characteristics of the drug particles to increase solubility.

[0012] This mechanism of increasing drug solubility by physical means is well described in the Noyes- Whitney equation [4] which states that upon reduction of the particle size of the active pharmaceutical ingredient (API) to the sub-micron range, the dissolution rate of the API increases, thereby reducing the effective boundary layer thickness. However, it is directly proportional to the surface area of the particles. Emulsion-based strategies are equally widely used in the pharmaceutical industry to increase drug solubility and dissolution rate. In this case, nanoemulsions or microemulsions are used to encapsulate hydrophobic drugs, which are subsequently made soluble in aqueous solutions. Depending on the solvency of the emulsion, only hydrophobic actives with a narrow range of Log P can be solubilized in these solutions.

[0013] Therefore, there is a need for a microemulsion system that can facilitate the solubilization of a wide range of actives, including highly poorly soluble hydrophobic actives (i.e. Log P of 9) to less hydrophobic compounds (Log P lower than 3).

[0014] Furthermore, merely increasing the dissolution of orally administered actives in the GIT is not sufficient to increase their bioavailability in the systemic circulation. There is also a need for strategies aimed at increasing their permeability through the epithelial layer of the intestine and ensuring prolonged residence time in the blood to achieve high drug concentrations. SUMMARY

[0015] According to a first aspect of the application, there is provided a polymer-lipid nanocomplex comprising:

[0016] i. an internal microemulsion matrix comprising at least one hydrophobic active compound, at least one fatty acid dissolved in a polar aprotic solvent and a surfactant; and

[0017] ii. an outer shell comprising one or more hydrophilic polymers.

[0018] The shell can in particular comprise an aqueous solution of a hydrophilic polymer, such as an aqueous mixture of polyvinyl alcohol (PVA) and polyethylene glycol (PEG) (e.g. PEG 4000).

[0019] The internal microemulsion base can also comprise at least one organic carboxylic acid. The at least one organic carboxylic acid can be a weak acid, including those weak acids approved for human consumption, including acetic acid, lactic acid, citric acid or phosphoric acid, preferably acetic acid.

[0020] Additionally, the internal microemulsion base can comprise at least one copolymer (poly(lactic-co-glycolic acid) or PLGA) or, alternatively, any biocompatible and biodegradable polymer suitable for drug delivery, including polylactic acid, polyglycolic acid or poly-epsilon-caprolactone.

[0021] Preferably, the at least one fatty acid comprises or consists of any one or more of stearic acid, palmitic acid and lauric acid, preferably stearic acid.

[0022] The polar aprotic solvent can comprise ethanol or acetone, or can be a mixture of ethanol and acetone. Preferably, the polar aprotic solvent is acetone.

[0023] The surfactant can comprise any surfactant having a hydrophilic-lipophilic balance (HLB) value greater than 10. Preferably, the surfactant is polysorbate 80, also known as Tween

[0024] According to another aspect of the present application, there is provided a process for producing a polymer-lipid nanocomplex comprising at least one hydrophobic active compound, the process comprising the steps of:

[0025] I. mixing at least one hydrophobic active compound, a fatty acid dissolved in a polar aprotic solvent and a surfactant to form an organic phase;

[0026] II. optionally heating the organic phase;

[0027] III. partitioning the organic phase into an aqueous mixture comprising at least one hydrophilic polymer to form a microemulsion; and

[0028] IV. stabilising the microemulsion in a phosphate buffer at about 0°C to form a nanodeposit of polymer-lipid nanocomplex.

[0029] The process can further comprise a final step of drying the nanodeposit by freeze-drying or spray-drying to produce a free-flowing polymer-lipid nanocomplex powder.

[0030] The process can further comprise mixing an organic carboxylic acid with the organic phase.

[0031] The process can further comprise dissolving at least one biocompatible and biodegradable polymer or copolymer suitable for drug delivery (poly(lactic-co-glycolic acid) or PLGA, or polylactic acid, polyglycolic acid or poly-epsilon-caprolactone) into a polar aprotic solvent containing a fatty acid to mix with at least one hydrophobic active compound and a surfactant, thereby forming an organic phase.

[0032] The at least one fatty acid can comprise any one or more of stearic acid, palmitic acid and lauric acid, preferably stearic acid.

[0033] The polar aprotic solvent can comprise ethanol or acetone, or can be a mixture of ethanol and acetone. Preferably, the polar aprotic solvent is acetone.

[0034] The organic carboxylic acid can comprise at least one weak acid. For example, the weak acid can comprise any one or more of those weak acids approved for human consumption, including acetic acid, lactic acid, citric acid or phosphoric acid. Preferably, the weak acid is acetic acid.

[0035] The surfactant can comprise any surfactant having a hydrophilic-lipophilic balance (HLB) value greater than 10. Preferably, the surfactant is polysorbate 80, also known as Tween

[0036] In particular, the process can comprise:

[0037] a) dissolving at least one fatty acid in a polar aprotic solvent to form a fatty acid solution;

[0038] b) dissolving at least one hydrophobic active compound in the fatty acid solution;

[0039] c) dropwise adding a surfactant to form an organic phase;

[0040] d) optionally heating the organic phase;

[0041] e) partitioning the organic phase into an aqueous mixture comprising at least one hydrophilic polymer while stirring to form a microemulsion; and

[0042] f) nano-precipitating the microemulsion by adding a phosphate buffer at 0°C while stirring, thereby forming a polymer-lipid nanocomposite.

[0043] The process can further comprise the step of drying the nano-precipitate by freeze-drying or spray-drying to produce a free-flowing polymer-lipid nanocomposite powder.

[0044] The process can further comprise dissolving PLGA or alternatively, any biocompatible and biodegradable polymer suitable for drug delivery including polylactic acid, polyglycolic acid or poly epsilon caprolactone, into the polar aprotic solvent containing fatty acid at step a).

[0045] The process can further comprise adding organic carboxylic acid and surfactant drop-wise at step c).

[0046] The process can further comprise heating while stirring to form the microemulsion at step e). The heating step can be performed at about 40°C to 50°C, preferably 40°C.

[0047] The phosphate buffer can comprise a pH of about 7.2 to about 7.6, more preferably about 7.4 at 0°C.

[0048] Nanoprecipitation of the microemulsion can be performed by adding the microemulsion to the phosphate buffer solution at a ratio of about 1 : 1. It will be appreciated that a variety of factors influence the optimal ratio of microemulsion to buffer, including drug loading, formulation stability (including during the drying process), and the like.

[0049] The freeze-drying can be performed after an initial freezing step in liquid nitrogen.

[0050] The spray-drying can be performed using a spray-dryer, such as a Top bench Buchi-B290. In particular, this spray-drying can be performed with the following set of parameters;

[0051] • Inlet temperature: about 90 to 110°C

[0052] • Outlet temperature: about 60°C

[0053] • Feed rate: 2% (mL / min)

[0054] • Atomization pressure: 6-7 bar

[0055] • Vacuum suction set at 100%.

[0056] It will be appreciated that the inlet temperature should be high enough to evaporate the polar (water) and non-polar (organic) solvents without degrading any of the compounds in the formulation, and that the range provided is one embodiment of the application and can be modified by one skilled in the art.

[0057] It will also be appreciated that the outlet temperature is influenced by the room temperature of the laboratory in which the equipment is located, and that the specific temperature can vary except that it is required to be higher than 60°C to obtain a dry, free-flowing powder. The outlet temperature is also controlled by the liquid feed rate, the inlet temperature and the efficiency of heat exchange between the liquid droplets and the dry hot air.

[0058] The size of the dried polymer-lipid nanocomplexes can be in the range of about 150 nm to 500 nm.

[0059] The size of the liquid polymer-lipid nanocomplexes can be in the range of about 70 nm to 150 nm.

[0060] The dried polymer-lipid nanocomplexes can include a polydispersity index (PDI) of 0.3 or less.

[0061] According to another aspect of the present application, there is provided a method of enhancing water solubility and absorption of at least one hydrophobic active compound, comprising formulating the at least one hydrophobic active compound using the process of the present application.

[0062] The at least one hydrophobic active compound can include any of the hydrophobic active compounds in the Log P positive scale (Log P 2 to Log P 9) of the partitioning scale. For example, the at least one hydrophobic active compound can include any one or more of an antitubercular drug, an antimalarial drug, and a phytochemical having antifungal, antiviral, anxiolytic, antiobesity, antidepressant, and / or analgesic properties.

[0063] In particular, the at least one hydrophobic active compound can include an antimalarial agent, more particularly Lumefantrine.

[0064] More particularly, the at least one hydrophobic active compound can include a phytochemical, more particularly Cannabidiol (CBD).

[0065] More particularly, the at least one hydrophobic active compound can include an antitubercular drug, more particularly Rifampicin.

[0066] For example, the at least one hydrophobic active compound formulated according to the present application can be administered by a variety of routes, including topical, subcutaneous, intravenous, intramuscular, inhalation, intranasal, sublingual, buccal, rectal, or intraocular administration.

[0067] According to another embodiment of the present application, there is provided at least one hydrophobic active compound formulated as a polymer-lipid nanocomplex of the present application.

[0068] According to another embodiment of the present application, there is provided at least one hydrophobic active compound formulated as a polymer-lipid nanocomplex of the present application for use in a method of treatment or prevention of a subject.

[0069] According to another embodiment of the present application, there is provided a method of treating or preventing a subject by administering at least one hydrophobic active compound formulated as a polymer-lipid nanocomplex of the present application.

[0070] Administration can be by a variety of routes, including topical, subcutaneous, intravenous, intramuscular, intranasal, sublingual, inhalation, buccal, rectal, or intraocular. BRIEF DESCRIPTION OF DRAWINGS

[0071] Figure 1 Size distribution and PDI of LUM microemulsion are shown;

[0072] Figure 2 DSC thermogram of nanocomposite LUM compared to free drug is shown;

[0073] Figure 3 Direct comparison plot of LUM delivery compared to nanocomposite LUM at an equivalent dose of 20 mpk LUM orally administered in male Balb / c mice is shown;

[0074] Figure 4 Graph showing in vivo efficacy results of nanocomposite LUM in a NSG mouse model of malaria infection; and

[0075] Figure 5 In vivo dose-response relationship graph of nanocomposites loaded with LUM is shown.

[0076] Figure 6 Size distribution and PDI of CBD microemulsion are shown;

[0077] Figure 7 Size distribution and PDI of CBD powder are shown;

[0078] Figure 8 Size distribution, PDI, zeta potential, yield, and drug loading of RIF powder are shown;

[0079] Figure 9 Morphology (SEM) of RIF powder is shown; and

[0080] Figure 10 In vitro release profile graph of nanocomposites loaded with RIF is shown. DETAILED DESCRIPTION

[0081] The present invention relates to a polymer-lipid nanocomposite comprising: an internal microemulsion matrix comprising at least one hydrophobic active compound; and an outer shell comprising a polymer for enhancing water solubilization and absorption of the hydrophobic active compound, a process for producing such nanocomposite, and methods of using such nanocomposite.

[0082] Although the Applicant has shown that several hydrophobic active compounds with different Log P values, including antitubercular drugs, antimalarials and phytochemicals with antifungal, antiviral, anxiolytic, antiobesity, antidepressant and / or analgesic properties, can be successfully incorporated into such polymeric-lipidic nanocomplexes, the present application will be described in terms of three exemplary embodiments: the antimalarial drug benflumetol, the phytochemical cannabidiol and the antitubercular (TB) drug rifampicin.

[0083] This is a simple, easy to scale up process that only requires conventional pharmaceutical equipment for commercial scale production.

[0084] The following examples are for illustrative purposes only and should in no way be construed as limiting the scope of the present application in any manner.

[0085] Example 1

[0086] Benflumetol (Log P 9) - Antimalarial drug

[0087] 1. Background

[0088] Benflumetol is a racemic mixture of synthetic fluorene derivatives that is insoluble in water (Log P of 9) and has the chemical structure shown in Formula 1.

[0089]

[0090] Benflumetol is used to treat acute uncomplicated malaria caused by the protozoan parasite Plasmodium falciparum (P. falciparum). Benflumetol is administered in combination with the artemisinin derivative artemether to enhance efficacy. Benflumetol is a blood schizonticide that is active against the intraerythrocytic stage of P. falciparum infection in uncomplicated malaria and has a half-life (T1 / 2) of 4-5 days. While effective, there are several limitations that hinder the maximization of efficacy. It has low and slow absorption in the circulatory system, resulting in relatively low bioavailability, is extensively metabolized in the liver, and due to its high lipophilicity, it is highly bound to proteins (99.7%) upon entry into the blood. Thus, these limitations result in a longer period of time (Tmax) for benflumetol to reach peak concentrations; orally administered benflumetol takes approximately 6 hours to reach a maximum concentration (Cmax) of 7 pg / mL in the blood.

[0091] As noted above, the delayed absorption of benflumetol negatively impacts its bioavailability. Its insolubility in polar media (0.002% w / v) results in its high metabolism by liver enzymes and extensive binding to plasma proteins upon crossing the intestinal tract into the blood.

[0092] 2. Methods and Materials

[0093] Dissolve 200-300 mg of pheniramine maleate (LUM) in a solution of stearic acid dissolved in a polar aprotic solvent, acetone, wherein add about 50-100 μl of an organic carboxylic acid, acetic acid, and about 50-100 μl of a surfactant with a high hydrophilic-lipophilic balance (HLB) value, polysorbate 80 or Tween 80 The oil phase (internal) of the emulsion is produced to accelerate the dissolution of LUM.

[0094] The organic phase of LUM is first heated to 40°C and then rapidly dispensed into an aqueous solution of an aqueous mixture of hydrophilic polymers, polyvinyl alcohol (PVA) and polyethylene glycol (i.e. PEG 4000), while stirring moderately on a magnetic hot plate.

[0095] The microemulsion obtained has a very narrow size distribution, as shown in Figure 1 The emulsion is further stabilized by immediately transferring it under stirring into a large volume (1 :1 volume ratio) of ice-cold phosphate buffer solution (pH 7.4) at 0°C. The resulting suspoemulsion is then dried to produce a free-flowing powder either by a freeze-drying step followed by a rapid freezing step in liquid nitrogen or by spray-drying using a Topbench Buchi-B290 spray-dryer with the following set of parameters:

[0096] • Inlet temperature: 100°C

[0097] • Outlet temperature: 60°C

[0098] • Feed rate: 2% (mL / min)

[0099] • Atomization pressure: 6-7 bar

[0100] • Vacuum suction set at 100%.

[0101] 3. Results

[0102] The process produces a free-flowing powder encapsulating LUM with an effective payload efficiency of about 25% w / w and 90% of the nanoparticles have a size ranging from 200 to 300 nm with a polydispersity index (PDI) of 0.3 and less than 0.3.

[0103] The nanocomposite produced by the process is easily redispersed in water at a concentration of 25 mg / ml without any visible signs of precipitation and the nanosuspension remains stable.

[0104] The results show a significant increase in the amount of drug suspended in water compared to the intrinsic water solubility of the drug alone of only 0.002% w / v, thus achieving an improvement of more than 10,000 times.

[0105] Since the nanocomplex of LUM is able to form a transparent solution upon re-dispersion in aqueous media, it can be administered by a variety of routes, including oral or intravenous administration.

[0106] Thermal analysis (differential scanning calorimetry or DSC) of the free flowing powder showed the disappearance of the melting point peak of LUM, which can be interpreted as a transformation from its crystalline form to an amorphous structure (see Figure 2 ). This is beneficial since it indicates a rapid dissolution rate of the drug.

[0107] Pharmacokinetic and pharmacodynamic evaluation of nanoformulated LUM (PN35)

[0108] LUM was re-formulated as a lipid-polymer nanocomplex for delivery with the aim of improving its bioavailability and enhancing its therapeutic efficacy in vivo.

[0109] This experiment demonstrated that its pharmacokinetic parameters (i.e. Cmax) were 10 times that of the control containing unformulated LUM, with a particularly extended tail curve above the minimum inhibitory concentration (MIC) for several hours. This shows rapid absorption of LUM after oral administration, depicted by a short Tmax.

[0110] Enhanced absorption was observed in animal studies a few minutes after oral administration of the nanocomplexed LUM re-suspended in water. The maximum plasma concentration of 11.5 mg / mL, once reported, was achieved in less than 1 hour, thereby minimizing the lag time of LUM absorption. Furthermore, the effective dose (ED90) of LUM that has been reported to clear 90% of the parasitemia from the blood was significantly reduced from 12.01 mg / kg to 5.01 mg / kg (see Figure 3 , Figure 4 and Figure 5 ).

[0111] Example 2

[0112] Cannabidiol (Log P 6) - a phytochemical analgesic drug

[0113] 1. Background

[0114] Cannabidiol (CBD) is a naturally occurring compound or phytochemical found in the cannabis plant. It is one of the 113 cannabinoid compounds extracted from the cannabis plant and is the major phytocannabinoid compound, accounting for 40% of the total plant extract. It belongs to the class of cannabinoids and can be administered by inhalation (bioavailability ranging from 11% to 45%) as well as by oral administration (bioavailability of only 13% to 19%). The extract (Formula 2) can be administered in solution form for oral administration or as an additive in food preparation. It has important medicinal value for humans, including relief from pain and inflammation, control of anxiety, control of seizures, and also has antioxidant properties.

[0115]

[0116] Although CBD is derived from the cannabis plant, which is known for its psychoactive effects when used recreationally, CBD does not induce psychoactive effects like its co-synthesized cannabinoid tetrahydrocannabinol (THC), which is the major psychoactive ingredient in the plant. It has also been hypothesized that it can act as an antagonist to THC as they bind to the same receptors found in the central and peripheral nervous system of the human body.

[0117] CBD research worldwide has shown a number of apparent health benefits, including pain and inflammation-reversing effects. Additionally, in several human studies, the combination of CBD with THC has shown effective treatment for multiple sclerosis and arthritis pain. In a recent study on cancer patients, a reduction in cancer-related symptoms was also observed. Through its antioxidant properties, anti-tumor effects, reduction in acne prevalence, antipsychotic effects, improved heart health, and good neuroprotective properties. Some studies suggest that treatment with CBD can prevent diabetes and also greatly reduce anxiety and depression. It is also used to treat patients with substance (drugs, etc.) abuse. Although the extract has been proven to be beneficial for treating a variety of diseases, it can also cause some adverse immune reactions. Side effects include nausea, vomiting, drowsiness, dizziness, and diarrhea, appetite changes, anxiety, depression, and confusion. The exact mechanism of its beneficial health effects is not clear, but cannabidiol seems to prevent the breakdown of chemicals in the brain that affect pain, mood, and mental function. Preventing the breakdown of this chemical and increasing its content in the blood seems to reduce psychotic symptoms associated with conditions such as schizophrenia.

[0118] The extract is not soluble in water (0.0126 mg / mL), is a colorless crystalline powder, and is soluble in various organic solvents. Although CBD is known to be non-psychoactive, it is highly insoluble in water, which hinders absorption, and also undergoes significant first-pass metabolism. Both of these properties are major limitations in therapeutic outcomes, and also result in low bioavailability when administered orally.

[0119] 2. Methods and materials

[0120] Liquid formulation

[0121] CBD (10-20 mg) is dissolved in a co-solution of stearic acid and acetone / ethanol, followed by the addition of 10-20 μΐ of a high HLB value surfactant (Tween 80 or Span 80) with a HLB value higher than 10 to help form the oil phase droplets. PLGA or alternatively, any biocompatible and biodegradable polymer suitable for drug delivery (including polylactic acid, polyglycolic acid or poly-epsilon-caprolactone) can also be optionally dissolved in the co-solution of stearic acid and acetone / ethanol to further improve the stability of the hydrophobic active in the internal matrix of the microemulsion.

[0122] To form the liquid microemulsion, the organic phase is rapidly dispensed into an aqueous solution of an aqueous mixture of hydrophilic polymers polyvinyl alcohol (PVA) and polyethylene glycol (i.e. PEG 4000). The organic phase can optionally be first heated to about 40°C, then upon dispensing into the aqueous mixture of hydrophilic polymers, moderate stirring can be used at about 40°C using a magnetic hot plate, resulting in a stable microemulsion with reproducible droplet size and size distribution.

[0123] Powder formulation

[0124] CBD (200-300 mg) is dissolved in a solution of stearic acid dissolved in a polar aprotic solvent, acetone, with the addition of about 50-100 μΐ of an organic carboxylic acid, acetic acid, and 10-20 μΐ of a surfactant with a hydrophilic-lipophilic balance (HLB) value greater than 10, polysorbate 80 or Tween 80 The oil phase (internal) of the emulsion is created.

[0125] The dissolved CBD oil phase is then rapidly dispensed into an aqueous solution of an aqueous mixture of hydrophilic polymers polyvinyl alcohol (PVA) and polyethylene glycol (i.e. PEG 4000) with moderate stirring. The dissolved CBD oil phase can optionally be heated to about 40°C prior to addition to the aqueous mixture of hydrophilic polymers and moderate stirring can be performed on a magnetic hot plate at about 40°C.

[0126] The CBD emulsion is further stabilized by the incorporation of a large volume (1 : 1 volume ratio) of ice-cold phosphate buffered solution (PBS) pH 7.4 at 0°C with stirring.

[0127] The stabilized emulsion is dried to produce a free-flowing powder either following a rapid freezing step by immersion in liquid nitrogen and subsequent freeze-drying or by spray-drying using a Top bench Buchi-B290 spray dryer under the following conditions:

[0128] ​• Inlet temperature: 100 °C

[0129] • Outlet temperature: 60 °C

[0130] • Feed rate: Pump knob set to 2

[0131] • Atomization pressure: 6-7 bar

[0132] • Vacuum suction set to 100%.

[0133] 3. Results

[0134] Liquid formulation

[0135] A water-based microemulsion system (water > 95%) incorporating CBD was successfully developed using an oil-in-water single emulsion nano-precipitation technique. The emulsion incorporated 2 mg of CBD per 1 mL of water (an increase of over 50-fold) with a uniform size distribution and depending on the CBD concentration and solvent to water ratio, the oil droplet size ranged from 70 nm to 150 nm ( Figure 6 ). All formulations incorporating low to high concentrations of CBD were stable for over 6 months and all maintained their initial size and size distribution with a size change of less than 2% (± 3 nm).

[0136] Powder formulation

[0137] CBD powder was water soluble with a size distribution ranging from 200 nm to 460 nm ( Figure 7 ). The stability of the CBD powder was investigated at room temperature and under refrigeration at about 4 to 8 °C and was found to be stable for over six months.

[0138] Example 3

[0139] Rifampicin (Log P 3.85) - Anti-tuberculosis drug

[0140] 1. Background

[0141] Today, nearly one-third of the world's population is infected with latent tuberculosis (TB), resulting in 2 million deaths per year. TB is caused by the bacillus Mycobacterium tuberculosis (M.TB) that typically attacks the lungs, but other body systems are also affected, including the central nervous system, lymphatic system, bones, and skin. TB is an airborne disease that is usually spread by infected individuals in the air through coughing, sneezing, or spitting. Infection occurs upon inhalation of bacteria that are phagocytosed by alveolar macrophages, and throughout disease progression, bacteria remain predominantly within macrophages. Here, bacteria can either remain in a latent state or multiply and disseminate to other sites and / or spread to other individuals. Current treatment is laborious, requiring patients to take high doses of combination therapy drugs (Isoniazid, Rifampicin, Pyrazinamide, and Ethambutol) daily for a duration of at least 18 months, often with severe drug-related side effects. As a result, patient compliance with the treatment regimen is low, which is an important cause of the emergence of drug-resistant M.TB strains. Multi-drug resistant TB (MDR-TB) strains are defined as strains that are resistant to the first-line drugs Isoniazid and Rifampicin.

[0142]

[0143] In 2008-2009, the number of MDR-TB cases reported to WHO reached an all-time high, with an estimated 500,000 new cases of MDR-TB each year. Drug-resistant TB is more deadly and significantly more difficult to treat and more expensive to treat than drug-susceptible TB. In South Africa, the recommended MDR-TB treatment regimen consists of a 6-month intensive phase (requiring hospitalization throughout the intensive phase), daily administration of one injectable drug, kanamycin, and simultaneous administration of at least four pills (Ethionamide, Ofloxacin, Terizidone or Cycloserine), and an 18-month continuation phase, taking four pills daily. These drugs exhibit significant toxicity, for example, kanamycin is associated with severe dose-dependent hearing impairment and kidney impairment. Most patients experience permanent hearing loss after completing treatment. In addition, failure to adhere to treatment can result in the development of strains of bacteria that are extremely highly drug resistant (XDR-TB). Such strains are more difficult to treat with currently available antibiotics. XDR-TB treatment consists of injectable Capreomycin and oral administration of Ethionamide, P-aminosalicylic acid, Moxifloxacin, Terizidone, Pyrazinamide and Clofazimine. The length of the intensive phase is guided by culture conversion, but is recommended to be at least 6 months, while the continuation phase is recommended to be at least 18 months. Again, these drugs exhibit severe side effects, and, coupled with the nature of the treatment regimen, make adherence difficult for patients. Patients also face the prospect of developing further resistance to XDR-TB, known as totally drug resistant TB (TDR-TB), which is currently considered incurable.

[0144] The focus of this project is to encapsulate rifampicin in biodegradable / biocompatible polymers and lipids. This will improve absorption, protect the drug from first-pass metabolism, and subsequently increase drug bioavailability by extending the plasma half-life.

[0145] 2. Methods and materials

[0146] 200-300 mg of rifampicin (RIF) is dissolved in a solution of stearic acid dissolved in a polar aprotic solvent, acetone. Optionally, PLGA or alternatively, any biocompatible and biodegradable polymer suitable for drug delivery, including polylactic acid, polyglycolic acid or poly-epsilon-caprolactone, can also be dissolved in a polar aprotic solvent to improve the stability of the hydrophobic RIF in the internal matrix of the microemulsion. About 10-20 μΐ of a surfactant, Tween 80, with a hydrophilic-lipophilic balance (HLB) value greater than 10 is added to the solution. The solution is then homogenized using a high-speed homogenizer at 10,000 rpm for 5 minutes. The solution is then filtered through a 0.22 μιη filter to remove any undissolved particles. The solution is then injected into the tail of a New Zealand white rabbit. The droplets accelerate RIF dissolution, creating the oil phase (internal) of the emulsion. The dissolved RIF is then added to the excipient pool consisting of PVA and PEG to form the emulsion. The resulting emulsion is immediately transferred to a cold PBS (pH 7.4) buffer solution at 0 °C in a 1 : 1 ratio to further stabilize the emulsion. The emulsion is then dried to produce a free-flowing powder either by a freeze-drying step followed by a quick freezing step in liquid nitrogen or by spray-drying using a Top bench Buchi-B290 spray dryer with the following set of parameters:

[0147] • Inlet temperature: 100 °C

[0148] • Outlet temperature: 60 °C

[0149] • Feed rate: Pump knob set to 2

[0150] • Atomization pressure: 6-7 bar

[0151] • Vacuum suction set to 100%.

[0152] 3. Results

[0153] The hydrodynamic size was on average ~246 nm with a good distribution below 0.3 Figure 8 ). The morphology was observed by scanning electron microscopy (SEM) and the results revealed spherical particles Figure 9 ).

[0154] The encapsulation efficiency was above 75% w / w with a solid recovery above 90%. The drug loading of RIF was between 7% and 10%. The latter relatively low drug loading for a hydrophobic drug like RIF can be due to the tendency of RIF to precipitate outside the polymer shell.

[0155] In vitro release studies were performed in an oscillating water bath set at 37 °C and 100 rpm for 25 days. A solution of 1 mg / mL, 40 mg PLGA-RIF NPs was prepared in 40 mL PBS pH 7.4, all samples in triplicate.

[0156] A controlled release of RIF was observed throughout the 25-day period. An initial burst release was observed within the first few minutes, reaching a maximum concentration above 20 pg / mL, followed by a lower but sustained release throughout the study Figure 10 ).

[0157] References

[0158] 1. D. C. Vimalson, S. Parimalakrishnan, N. S. Jeganathan, S. Anbazhagan. Techniques to Enhance Solubility of Hydrophobic Drugs: An Overview. Asian Journal of Pharmaceutics · Apr-Jun 2016 (Suppl) · 10(2) | S67

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Claims

1. A process for producing polymer-lipid nanocomposites, comprising the following steps: I. A mixture of the following substances is used to form an organic phase: at least one hydrophobic active compound in the Log P positive scale of a partition coefficient table, wherein the Log P positive scale is selected from Log P 2 to Log P 9; a fatty acid dissolved in a polar aprotic solvent, wherein the polar aprotic solvent includes acetone, or a mixture of ethanol and acetone, wherein the fatty acid is stearic acid; and a surfactant polysorbate 80 with a hydrophilic-lipophilic balance (HLB) value greater than 10. II. Optionally, heat the organic phase; III. The organic phase is dispensed into an aqueous mixture of a hydrophilic polymer composed of polyvinyl alcohol and polyethylene glycol to form a microemulsion; as well as IV. Stabilize the microemulsion in phosphate buffer at 0°C to form a nanoprecipitate of the polymer-lipid nanocomposite.

2. The process according to claim 1, further comprising a final step: drying the nanoprecipitate by freeze-drying or spray drying to produce free-flowing polymer-lipid nanocomposite powder.

3. The process according to claim 1, further comprising mixing an organic carboxylic acid, including acetic acid, lactic acid, citric acid or phosphoric acid, with the organic phase.

4. The process according to claim 1, wherein the process further comprises using at least one biodegradable and biocompatible polymer or copolymer, poly(lactic acid-co-glycolic acid) or polylactic acid, polyglycolic acid or poly(lactic acid-co-glycolic acid). - Caprolactone is dissolved in the polar aprotic solvent containing the fatty acid to be mixed with the at least one hydrophobic active compound and the surfactant to form the organic phase.

5. The process according to claim 1, wherein in step IV., the nanoprecipitation of the microemulsion is carried out by adding the microemulsion to the phosphate buffer at a 1:1 ratio.

6. A method for enhancing the water solubility and absorption of at least one hydrophobic active compound, comprising formulating the at least one hydrophobic active compound according to any one of claims 1 to 5.

7. The polymer-lipid nanocomposite obtained by the process according to any one of claims 1 to 5.

8. The polymer-lipid nanocomposite according to claim 7, the process according to any one of claims 1 to 5, or the method according to claim 6, wherein the at least one hydrophobic active compound is the antimalarial agent benzofluorenol.

9. The polymer-lipid nanocomposite according to claim 7, the process according to any one of claims 1 to 5, or the method according to claim 6, wherein the at least one hydrophobic active compound is cannabidiol.

10. The polymer-lipid nanocomposite according to claim 7, the process according to any one of claims 1 to 5, or the method according to claim 6, wherein the at least one hydrophobic active compound is the anti-tuberculosis drug rifampin.

11. The method of claim 6, wherein the at least one hydrophobic active compound is formulated for administration via subcutaneous, intravenous, intramuscular, intranasal, sublingual, oral, or intraocular routes.

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