KR20040095362A - Stabilized natural cannabinoid formulation - Google Patents

Abstract

The present invention provides a natural cannabinoid compound (eg, Δ ⁹ -tetrahydro), characterized in that the natural cannabinoid compound is incorporated into sugar glass as a single molecule capsule without forming a guest-host complex. Cannabinol) and sugars, sugar alcohols, mixtures of sugars or mixtures of sugar alcohols. The present invention further relates to a process for preparing a pharmaceutical composition in the form of sugar glass by spray drying, freeze drying, vacuum drying or critical drying method of a stable mixture containing a natural cannabinoid compound and a sugar or a mixture of sugars. .

Description

Stabilized natural cannabinoid formulation

The present invention relates to pharmaceutical formulations which stabilize natural cannabinoid compounds, in particular Δ ⁹ -tetrahydrocannabinol (THC). The invention also relates to a method of making such a formulation.

Natural cannabinoid compounds, which can be obtained from several natural sources, are usually obtained from Cannabis Sativa , can be used as therapeutics for treating a wide variety of diseases. For an overview of natural cannabinoids, see David T. Brown ed., Cannabis, Harwood Academic Publishers 1998, ISBN 90-5702-291-5. An example of a natural cannabinoid compound is THC, commercially available as Marinol ^R (common name: dronabinol). Currently, THC is formulated as soft gelatin capsules for oral administration in which the drug is dissolved in oil. The disadvantage is that THC is not stable in such formulations. As a result, it should be stored at low temperature (4 ° C.). The low stability of the compound and the need to store the pharmaceutical formulation in the refrigerator is obviously a major drawback of pharmaceutical products.

It is an object of the present invention to provide formulations for unstable natural cannabinoid compounds, such as THC, which have improved the stability of the compounds for long-term storage at ambient temperature. Yet another object is to provide a method for obtaining a pharmaceutical substance in anhydrous powder state. Anhydrous status offers the possibility of developing other dosage forms, such as anhydrous powders for pulmonary administration and tablets for oral or sublingual administration.

WO9932107 describes the use of cyclodextrins for the dissolution of THC in two-phase delivery systems or microsphere delivery systems. The lytic action of cyclodextrins is caused by the formation of so-called inclusion complexes or guest-host complexes. The purpose of the subject matter of WO9932107 is to dissolve THC to promote absorption from the nasal cavity. The application does not describe the stability of the formulated THC at all. Since it is known to those skilled in the art that these guest-host complexes sometimes have stabilizing effects but in other cases result in attenuation of the active compounds due to catalysis, nothing can be concluded in advance regarding the stabilizing effect of guest-host complex formation. none. Cyclodextrins also have the disadvantage of causing mucosal irritation when applied as an intranasal or pulmonary formulation. In particular, cyclodextrin derivatives with surfactant properties are stimulants of mucosal tissue.

WO9736577 describes the use of anhydrous solid lipid compositions useful for oral administration of lipophilic compounds, such as natural cannabinoids, including solid fats and phospholipids in addition to active substances. The purpose of such compositions is to increase oral bioavailability, not to increase the stability of the active substance.

WO0078817 describes a method for stabilizing alkaline phosphatase by drying proteins from pure aqueous solutions in the presence of inulin oligosaccharides. During drying, the protein is encapsulated in single molecules by a matrix of amorphous inulin that is free. In particular, stabilization is achieved because the protein is vitrified and protected from the environment. However, alkaline phosphatase is a hydrophilic compound that is highly soluble in water and can be formulated directly from an aqueous solution. Stabilization also relates to the preservation of tertiary and quaternary structures of proteins, which are particularly important for enzymatic activity.

WO9118091 describes the use of non-reducing sugar molecules, especially monoglycosides such as maltitol, lactitol and palatinit to preserve the stability of enzymes that are hydrophilic compounds (eg, restriction endonuclease Pst I) and antibodies. Describe the use. According to this patent application, stabilized enzymes can be prepared by mixing the enzymes with sugars and proprietary buffers and then air drying. This method cannot be used for lipophilic compounds because these compounds cannot be dissolved in sufficient amounts in the polar system. Maltitol and lactitol have a glass transition temperature of 44 ° C. (33 ° C. in anhydrous state) (Y. Roos, Carbohydrate Research 1993, 238, 39-48).

It has now been surprisingly found that highly lipophilic compounds, such as natural cannabinoid compounds, can be stabilized against oxidation and isomerization by incorporation into sugar glass or sugar alcohol glass by the mechanisms mentioned above. It has also been found that sugar free techniques result in improved bioavailability. Since natural cannabinoid compounds are incorporated as single molecules, the dissolution rate of these compounds will be determined by the dissolution rate of sugar glass. Since the dissolution rate of sugar glass is much faster than the dissolution rate of the natural cannabinoid compound, the drug will be provided to the absorbent membrane more quickly.

In a first aspect, the present invention provides a natural cannabinoid compound and a sugar or sugar alcohol or sugar or salt, characterized in that the natural cannabinoid compound is incorporated into the sugar as a single molecule capsule without forming a guest-host complex. It relates to a pharmaceutical composition comprising a glass of a mixture of sugar alcohols. The compound is incorporated into the sugar glass when a monomolecular inclusion of almost all cannabinoid molecules is present in the sugar matrix. Thus, the delivery system according to this aspect of the invention formed can be regarded as a one-phase delivery system. Natural cannabinoid molecules are randomly oriented in the sugar glass. Unlike guest-host complexes such as complexes with cyclodextrins, once dissolved, there is no interaction between the cannabinoid compound and the dissolved sugar molecule.

By incorporating the cannabinoid compound into the sugar glass, the glass transition temperature (Tg) of the sugar glass will be reduced, the Tg of the cannabinoid compound will be extinguished, and the dissolution rate of the cannabinoid compound will be increased. In addition, scanning electron microscopy can show whether the compound is incorporated. The most preferred natural cannabinoid compound is THC.

In order to obtain the best stability, the sugar glass preferably has a glass transition temperature (Tg) of at least 50 ° C. under normal environmental conditions and a low tendency to crystallize. Normal environmental conditions are defined as 20-25 ° C. and relative humidity of 40% or less.

In the present invention, the expression "natural cannabinoid compound" includes non-natural derivatives of cannabinoids which can be obtained by derivatization of natural cannabinoids and which can be unstable, such as natural cannabinoids.

In the present invention, the expression "sugar" includes a polysaccharide, and the expression "sugar alcohol" includes a polymer sugar alcohol. Preferred sugars in the present invention are non-reducing sugars. Non-reducing sugars are sugars that do not have or cannot form reactive aldehydes or ketone groups. Examples of non-reducing sugars are trehalose and fructanes such as inulin.

Preferred non-reducing sugars for use in the present invention are fructans or mixtures of fructans. Fructan is understood to mean all oligosaccharides or polysaccharides containing a number of anhydrous fructan units. Fructan may have a polydisperse chain length distribution and may have a straight or branched chain. Preferably, the fructans may contain mainly β-1,2 bonds as in inulin, but they may also contain β-2,6 bonds as in levan. Suitable fructans may originate directly from natural sources, but may be modified. An example of a modification is the reaction as is known which leads to an extension or shortening of the chain length. In addition to the polysaccharides present in nature, industrially produced polysaccharides are suitable in the present invention, for example hydrolysates with shortened chains and fractionated products with modified chain lengths. The hydrolysis reaction can be carried out enzymatically (e.g. using endoninase), chemically (e.g. using aqueous acid), physically (e.g. For example, by heat), or using heterogeneous catalysis (eg, using an acid ion exchanger). Fractionation of fructans, for example inulin, can be achieved, in particular, through crystallization at low temperatures, separation using column chromatography, membrane filtration, and selective precipitation with alcohol. Other fructaxes, such as long chain fructans, can be obtained, for example, through crystallization from fructans from which monosaccharides and disaccharides have been removed. Frutans with enzymatically extended chain lengths can also be used as fructans in the present invention. In addition, reduced fructans may be used in which the reducing end groups, typically fructose groups, are fructans reduced by, for example, hydrogen or sodium borohydride in the presence of a transition metal catalyst. Chemically modified fructans such as crosslinked fructans and hydroxyalkylated fructans may also be used. The average chain length in all these fructans is expressed as number average degree of polymerization (DP). The abbreviation DP is defined as the average number of sugar units in the oligo- or polymer.

More preferred reducing sugars in the present invention are inulin or a mixture of inulin. Inulin is an oligosaccharide and a polysaccharide composed of β-1,2 bonded fructose units having α-D-glucopyranose units at the reducing end of the molecule, and different degrees of polymerization (DP) can be used. Preferred inulins are inulins having at least 6 DPs, or mixtures of inulins, wherein each inulin has at least 6 DPs. Even more preferred inulin is an inulin or a mixture of inulin with a DP of 10 to 30. Most preferred are inulin or a mixture of inulins with a DP of 15 to 25. Inulin is particularly present in the roots and tubers of plants of the family Liliaceae and Compositae . The most important sources for the production of inulin are the Jerusalem saliva artichoke, dahlia and chicory roots. Industrial manufacturing mainly starts with chicory roots. The main difference between inulins originating from different natural sources is the degree of polymerization (DP), which can vary from about 6 for Jerusalem saliva artichoke to 10 to 14 for chicory roots and over 20 for dahlias. have. Inulin is an oligosaccharide or polysaccharide having physicochemical properties that is advantageous for use as an auxiliary substance in pharmaceutical formulations in an amorphous state. These physicochemical properties are (adjustable) high glass transition temperatures, the absence of reducing aldehyde groups, and typically low speed crystallization. Inulin is also non-toxic and inexpensive.

The weight ratio of natural cannabinoid compound to sugar or sugar alcohol is usually in the range of 1: 5 to 1: 100, more preferably in the range of 1:10 to 1:50, most preferably 1:12 to 1: Is in the range of 25.

Pharmaceutical compositions according to the invention may be used in tablets (eg, conventional oral tablets, sublingual tablets, oral tablets, or orally disintegrating or soluble tablets), capsules, lozenges, enema, suppositories, products for transdermal administration, lungs It may be further processed into a powder for administration or a rod or suspension for subcutaneous or intramuscular administration. These dosage forms are known in the art and those skilled in the art can process the compositions according to the invention into the desired dosage forms. Preferred formulations are intended for oral or pulmonary administration.

A suitable technique for the production of sugar glass according to the invention is the freeze drying method. In addition, other drying techniques can be used, for example spray drying, vacuum drying and supercritical drying. Using these techniques, the first step in preparing sugar glasses incorporating natural cannabinoid compounds is to prepare a solution in which both materials are dissolved. However, due to the hydrophilicity of sugars and the lipophilic nature of natural cannabinoid compounds, it is difficult to dissolve these compounds in the same solvent. It has been found that this problem can be solved using a mixture of solvents. Water is an excellent solvent for sugars and sugar alcohols, while various organic solvents such as alcohols are good solvents for natural cannabinoid compounds. Since water and alcohol mix very well, there is a possibility that both substances will dissolve to some extent at certain water / alcohol ratios.

Therefore, the present invention,

a) dissolving the natural cannabinoid compound in an organic solvent soluble in water and dissolving the sugar or mixture of sugars in water;

b) the dissolved cannabinoid compound and the dissolved sugar or mixture of sugars are mixed to obtain a sufficiently stable mixture;

c) the mixture is lyophilized, spray dried, vacuum dried or supercritical dried, so that the natural cannabinoid compound is incorporated into the sugar glass as a monomolecular capsule without forming a guest-host complex. A method of preparing a pharmaceutical composition comprising a cannabinoid compound and a glass of sugar or a mixture of sugars.

Organic solvents suitable for forming stable mixtures with sugars, water and natural cannabinoid compounds include solvents which can be mixed with water such as dimethylsulfoxide (DMSO), N, N-dimethylformamide (DMF), acetonitrile, Ethyl acetate and lower alcohols. Since the solvent must be removed by spray drying or lyophilization, the solvent should preferably have a suitable vapor pressure at the drying temperature. Thus, lower alcohols, defined as C ₁ -C ₆ alcohols, wherein the alkyl moiety may or may not be branched, are preferred. More preferred alcohols are C ₂ -C ₄ alcohols such as ethanol, n-propyl alcohol and t-butyl alcohol. Most preferred solvent is t-butyl alcohol.

The ratio between the cannabinoid compound, the solvent, the water, and the sugar or mixture of sugars should be chosen so that a sufficiently stable solution is obtained. Optionally, surfactants can be added to improve stability. For example, if clouding does not appear in the solution within a treatment time of 120 minutes, 60 minutes, 30 minutes or 10 minutes, the solution is considered to be sufficiently stable. For spray drying a typical treatment time is 30 minutes. In the case of the lyophilization method, the solution must be clear until it is frozen. In this case, the typical treatment time is 10 minutes.

The amount of water after the drying process is preferably 3% or less. The amount of solvent is preferably 3% or less. It is apparent to those skilled in the art that the time required for drying can be inferred from parameters such as sample thickness, sample temperature, pressure and condenser temperature.

Although spray drying methods are used to prepare sugar glasses of cannabinoid compounds, the stability of the compounds is significantly improved, but the best results are obtained by the freeze drying method. Therefore, the most preferred drying method in the present invention is freeze drying. In the first step of the freeze drying method, the solution is frozen. This first step should preferably be carried out quickly and the sample temperature should be lowered below Tg '(the temperature of the frozen concentrated fraction) [D.L. Teagarden, Eur. J. Pharm. Sci., 15, 115-133, 2002]. Freeze drying below Tg 'yields a porous cake, whereas above Tg' yields a collapsed cake. Porous cakes are preferred because the porous cake can be more easily processed, for example, as a tableting powder or a formulation for pulmonary administration. Furthermore, lyophilization above Tg 'may result in crystallization of the sugar. This will interfere with the incorporation of the drug in the free state and consequently the stability will be reduced.

The following examples are merely intended to further illustrate the present invention in detail, and therefore, these examples should not be considered as limiting the scope of the present invention in any way.

Example 1: Δ ⁹ And Characterization of Inulin Glass of Tetrahydrocannabinol

material

Innulin, type TEX! 803, was provided by the manufacturer [Sensus, Roosendaal, The Netherlands]. Purified Δ ⁹ -tetrahydrocannabinol (THC) is a product of Unimed. All other chemicals were reagent or analytical grade and were purchased from commercial sources.

Way

Physical and chemical properties of inulin

Measurement of the degree of polymerization of inulin

The average degree of polymerization (DP) of inulin was determined as follows: The inulin solution was acidified to pH 1.45 by addition of 3N HCl. Subsequently, the temperature was raised to 80 ° C., whereupon inulin decomposed into fructose and glucose. After cooling to room temperature, the pH was adjusted to 6-9 by addition of 1.5 M NaOH. The fructose / glocos ratio was determined using HPLC. Aminex HPX-87C column was used. The sample was eluted with MilliQ-water at 80 ° C. at a flow rate of 0.6 mL / min. The amount of fructose and glucose was measured using an IR detector. DP is the ratio of fructose content and glucose content +1.

Determination of the number of reducing groups

The number of reducing groups was measured using the Sumner-test according to the method below. A solution of 20 g NaK-tartrate tetrahydrate, 1 g dinitrosalicyclic acid, 1 g NaOH and 200 mg phenol in 100 mL water was prepared. To 1.5 ml of this solution, 1.0 mL of an aqueous solution containing the sugar to be analyzed was added. Then 100 mL of a freshly prepared solution of 0.24 M Na ₂ SO ₃ in water was added to the mixture. The resulting mixture was vortexed and then placed in a 95 ° C. water bath. After 15 minutes, the sample was removed from the bath and cooled to room temperature. Absorbance of the sample was measured at 620 nm. The calibration curve was created using an aqueous solution with a glucose concentration of 0.10 to 1.00 mg / mL.

Differential Scanning Calorimetry (DSC)

The glass transition temperature (Tg) of lyophilized inulin, equilibrated at 0%, 45% and 60% relative humidity was measured by modulated DSC (DSC Differential Scanning Calorimetry, TA Instruments, Gent, Belgium). A modulation amplitude of ± 0.318 ° C. every 60 seconds and a heating rate of 2 ° C./min were used. During the measurement, sample cells were purged with nitrogen at a flow rate of 35 mL / min. The midpoint of the deflection in the reverse heat flow over the temperature curve was taken as Tg. Tg was measured twice. The glass transition temperature (Tg ') of the freeze-concentrated fraction of the 9.6% w / v solution of inulin in 60/40 v / v water / t-butyl alcohol mixture was measured using conventional DSC. The solution was cooled to -70 ° C at a cooling rate of 10 ° C / min. The sample was then heated to 40 ° C. at a rate of 2 ° C./min. In the meantime, the sample shock was purged with helium at a flow rate of 35 mL / min. The midpoint of the deflection in the heat flow over the temperature curve was taken as Tg '. Tg 'was measured twice.

Physical Stability of Amorphous Inulin

In order to evaluate the physical stability of amorphous inulin, the porous cake of amorphous inulin obtained by freeze drying was transported into a climate chamber controlled at 45% or 60% relative humidity, respectively, and humidified at 20 ° C. After equilibration, it was visually judged whether the sample remained unchanged or collapsed.

Dynamic Vapor Sorption

The water sorption isotherm of lyophilized inulin was measured using a gravimetric sorption analyzer (DVS-1000 Water Sorption Instrument, Surface Measurement Systems Limited, London, UK) at ambient pressure and 25 ° C. Inhalation of water by inulin was measured at each step of 10% relative humidity from 0% to 90% relative humidity. The initial sample weight was about 10 mg. It was estimated that equilibrium was reached when the change in weight was less than 0.9 μg in 10 minutes.

Physical and chemical properties of THC

Solubility in water

Pure water was added to the excess THC. The resulting dispersion was stirred at 20 ° C. using a magnetic stirrer. After 3 days, the dispersion was centrifuged and the concentration of THC in the supernatant was measured spectrophotometrically at 210 nm. Samples were diluted with ethanol. The calibration curve was established using a THC solution in ethanol at known concentrations (1.244-12.44 μg / mL).

Dynamic steam sorption

Water sorption of THC was measured according to the method described above for inulin. After THC was dissolved in methanol, it was put into a DVS-1000 instrument. During the initial exposure to the dry nitrogen stream, methanol was evaporated. As soon as about 90% of the solvent had evaporated, additional THC solution was added to the sample-cup. This process was repeated until 15 mg of pure THC was present in the sample-cup. After evaporation of the final methanol, the relative humidity was increased from 0% to 90% in 10% steps.

Differential Scanning Calorimetry (DSC)

The thermal action of THC was measured using mDSC. A modulation amplitude of ± 0.318 ° C. every 60 seconds and a heating rate of 2 ° C./min were used. During the measurement, Sample VII was purged with nitrogen at a flow rate of 35 mL / min. A drop of pure THC was placed in a sample cup. After initial cooling, the samples were first scanned to 50 ° C. In this method, the drops could spread over the entire bottom of the sample pan, thereby increasing the surface available for heat transfer during the second injection. The sample was then cooled to −40 ° C. and then heated to 350 ° C.

Preparation of THC Containing Samples

Preparation of solution for spray drying or freeze drying

Three different formulations for spray drying and one formulation for freeze drying were prepared (Table 2). Formulations 5, 6, 9 and 12 were prepared by dissolving inulin in water and THC in appropriate alcohol, respectively.

Suitable volume ratios of water / alcohol were investigated by testing the stability of 10% w / v inulin with different ratios of water / alcohol. Inulin was dissolved in different amounts of water (3-7 mL). Different amounts of alcohol were then added until the total volume was 10 mL. For THC, the same procedure was followed but water was added to the alcoholic THC solution. The solution was judged to be sufficiently stable if no cloudiness appeared within the treatment time. For spray drying, batches were prepared that required spraying up to 30 minutes. Thus, the solution must be transparent for at least that period. In the case of lyophilization, the solution must be clear until it is frozen. In this case, 10 minutes is sufficient. In addition, it was investigated whether the aqueous solution of inulin can be added slowly or should be mixed immediately.

Formulations for Spray Drying and Freeze Drying Formulation Drying method menstruum Inulin (mg / mL) THC / Inulin (m%) 9 Spray drying H ₂ O / EtOH = 50/50 (v / v) 47.73 4.00% 5 Spray drying H ₂ O / -PrOH = 60/40 (v / v) 49.00 3.34% 6 Spray drying H ₂ O / -PrOH = 60/40 (v / v) 46.17 7.77% 12 Freeze drying H ₂ O / t-BuOH = 60/40 (v / v) 96.00 4.00%

Spray drying

Spray drying was performed using a Buchi 190 mini spray dryer (Buchi, Flawil, Switzerland). Typical operating conditions were according to the following settings: nitrogen-gas inlet temperature: 148 ° C. (the outlet temperature was 87 ° C.), dry air flow 525 L / h, aspirator flow settings: 20, and pump adjustment settings: 6 After spray drying, the powder formed was collected in a 50 mL bottle and washed with nitrogen for about 15 minutes. The product was stored at -18 ° C.

Freeze drying

Freeze drying was performed using a Christ model alpha 2-4 lyophilizer (Salm en Kipp, Breukelen, The Netherlands). In a typical experiment, 20 mL glass vials were filled with a 2-5 mL solution. The solution was frozen with liquid nitrogen and then lyophilized for 1-3 days at a shelf temperature of −30 ° C., a condenser temperature of −53 ° C., and a pressure of 0.220 mBar. The storage temperature was then gradually raised to 20 ° C. and the pressure was gradually reduced to 0.05 mBar for 6 hours. The sample was stored for at least 1 day in a vacuum dryer.

Stability Study of THC Containing Solution

Samples were stored under five different conditions shown in Table 3: Samples were taken at different time intervals and the amount of undissolved THC was measured using HPLC. Pure THC and a physical mixture of THC and inulin were used as controls. Samples of pure THC were prepared as follows. 720.5 mg THC was dissolved in 20.00 mL methanol. 70 μL of this solution was transferred to a glass vial of 24 mm diameter. The solvent was then evaporated in a stream of dry nitrogen, leaving 2.52 mg of pure THC in the vial. About 192 mg of inulin was weighed and placed in a vial of 24 mm diameter to prepare a physical mixture. Then 200 μL of a methanolic solution of 36.025 mg / mL THC was added to give a mixture containing 4.0 mass% THC.

Storage Conditions for THC-Containing Samples Temperature (℃) Relative Humidity (%) Waiting 20 0 Low [O ₂ ] 20 45 air 20 60 air 47 0 Low [O ₂ ] 47 5 air

THC-analysis

Samples were analyzed using HPLC. These were prepared as follows. Methanol was added to the sample. Sonication for 10 minutes to disperse the product throughout methanol. The suspension thus obtained was shaken by hand. Samples were taken after two days of extraction. The sample was centrifuged and the supernatant diluted with methanol. In control experiments, it was found that sonication did not induce degradation of THC. During two days of extraction, no significant degradation of THC was measured. The ISCO model equipped with a Photodiode Array UV-VIS detector (Shimadzu SPD-M6A model) and a Chrompack Nucleosil 100 C18 column (4.6 × 250 mm) was used for the 2350 system. Samples (20 μL) were injected using a Kontron instrument HPLC 360 Autosampler and eluted with methanol / water = 86/14 (v / v). The flow rate was 1.5 mL / min. Absorbance was measured at 214 nm. The collected data was analyzed using SPD-MXA software. In the chromatogram of untreated THC, a large peak was observed at a residence time of 7.5 minutes. In the chromatogram of intentionally partially resolved THC, the peak at 7.5 min retention time decreased in size and new peaks appeared at shorter retention times. The peak at 7.5 min residence time was due to Δ ⁹ -THC. The other peak was due to decomposition products. The content of (undigested) THC in the treated samples was calculated from the area under the peak at the elution time of 7.5 minutes. The calibration curve was established using a solution of THC in methanol at known concentrations (0 to 122 μg / mL). At each HPLC-run, several calibration points were included. The solution used for this purpose did not show significant degradation for 2 weeks at 4 ° C. The measurement was performed at least twice.

result

Physicochemical Characterization of Inulin

The physico-chemical properties of the inulin used are summarized in Table 4.

Physico-Chemical Characterization of Inulin Glass Average degree of polymerization 23 % Sugars containing reducible groups 5.9 ± 0.1 Tg 155.4 ± 0.1 ℃ Tg ' -24 ℃ Physical stability at 20 ° C Stable at up to 45% RH; Collapse at less than 60% RH Hygroscopic Mass change = 0.22 ^* RH (%) +0.61

23 inulin DPs were found. For various reasons, this value should be considered as an indication. Inulin consists of a linear β-D- (2 → 1) linked fructose oligomer and the terminal is an α-D- (2 → 1) glucopyranose ring. Thus, DP can be calculated from the glucose / fructose ratios presented herein. However, commercially available inulin may contain inulin species from which glucose end groups have been cleaved. The presence of these species will overestimate DP. On the other hand, commercial inulin may also contain small amounts of glucose. The presence of these species will underestimate DP.

Due to the specific linkage between the monosaccharide rings, inulin should not contain reducing groups. However, the Summer test showed that 5.9 ± 0.1% sugar units of inulin used in this study contained reducing groups. The presence of the reducing group is mainly due to the inulin species from which the glucose end group is cleaved, but also because of the presence of monosaccharides. These monosaccharides can be glucose and fructose. Fructose is a non-reducing sugar. However, during the Summer assay, sugars are treated at high temperatures where fructose can be readily converted to glucose (Lobry de Bruyn van Ekenstein rearrangement). Indeed, in the control experiment, fructose showed one reducing group per molecule in the assay (data not shown). Thus, the measurand of the reducing group is probably overestimated.

The glass transition temperature (Tg) of Inulin was found to be 155.4 ± 0.1 ° C. This value is much higher than the Tg of trehalose (120 ° C.) and sucrose (76 ° C.), the sugars often used to stabilize unstable drugs. Higher Tg is important because the material changes to a rubbery state at temperatures above Tg. In the rubber state, the molecular mobility is greatly increased compared to the free state, and consequently, the rate of decomposition of the encapsulated drug substance is greatly increased. In addition, crystallization may occur in the rubber state. During crystallization, the incorporated drug substance is released from the stabilization matrix and the protection is completely lost. Tg may look very high. However, sugar glass absorbs water when exposed to humidified air (see below). Water acts as a plasticizer for sugar glass and greatly reduces Tg. Thus, inulin glass can absorb much more water than trehalose or sucrose before the Tg is reduced to room temperature.

Tg 'of inulin at -24 ° C was found. This value is also higher than trehalose (-36 ° C) and sucrose (-39 ° C). When the freeze drying method is selected as the drying method, it may be desirable to have a relatively high Tg 'because the sample temperature must be kept below Tg'. If the sample temperature is above Tg ', the freeze-concentrated fraction is rubbery and has a relatively high molecular mobility as mentioned above. Since the concentration of drug substance in the freeze-concentrated fraction is very high, the rate of degradation can be increased compared to the starting solution. Also in this case, crystallization of sugar can easily occur, accompanied by a weakening effect on the drug substance. Furthermore, freeze drying below Tg 'produces a porous cake, whereas above Tg' yields a cake that has collapsed. Porous cakes are preferred because they can be more easily processed into, for example, tableting powders or formulations for pulmonary administration.

The physical stability of inulin glass at 20 ° C. was evaluated by exposing the glass to air at various relative humidity. It has been found that the porous cake of inulin prepared by the lyophilization method remains unchanged at up to 45% RH. However, at 60% RH, the porous cake collapsed. This means that at between 45% and 60% RH, the sample absorbs water so that the Tg is neglected. Short-term exposure to 60% RH may be applied to the lyophilized cake, which may partially disintegrate. Such partially disintegrated material may form suitable rapid dissolving tablets having sufficient strength. Tg of lyophilized inulin after equilibration at 0, 45% and 60% is shown in FIG. 1.

Moisture intake of lyophilized inulin exposed to air of relative humidity in the range of 0 to 90% at 25 ° C. was measured using a gravimetric sorption analyzer. Over the entire range of relative humidity, a linear relationship was found between moisture intake and RH to which the sample was exposed (Table 5, FIG. 2). As found above, Tg is neglected at 45% to 60% RH. This linear relationship indicates that inulin crystallization does not occur during the time unit of time of the experiment. If crystallization occurs and anhydrous crystals are formed, the moisture content of the sample will drop to near zero. On the other hand, when crystals encapsulating water molecules are formed, the water content of the sample remains almost the same even if the RH is increased. This phenomenon has been observed in water sorption experiments with amorphous sugars such as trehalose, sucrose and lactose. Thus, the results indicate that amorphous inulin crystallizes less readily than amorphous trehalose, sucrose and lactose.

Physicochemical Characterization of THC

Solubility

It was found that the solubility of THC was 1 μg / mL or less (about 0.5 μg / mL).

Dynamic steam sorption

Pure THC was found to absorb only 0.3% moisture after exposure to 90% RH. This level of water intake may be due to adsorption on THC rather than absorption into THC.

Differential Scanning Calorimetry

Tg of 10 ° C. was found in the thermogram of THC. In addition, endothermic peaks starting at 200 ° C were found. From a thermodynamic point of view, crystallization is expected to occur just above Tg. However, it is known that THC is not easily crystallized. Eventually, THC at ambient temperature is in a rubber or liquid state. The endothermic peak is due to evaporation.

Preparation of THC Containing Samples

Water-ethanol solution for spray drying or freeze drying

Three related alcohols were added to the inulin solution in water. It was measured how long the obtained solution remained transparent. After 1 g of inulin was dissolved in 4 mL water, water and / or alcohol was added to a total volume of 10 mL to obtain a 10% w / v solution. This gave the maximum concentration of alcohol. THC was dissolved in the corresponding alcohol. Then alcohol and / or water were added to obtain a 0.4% w / v solution. The composition required to obtain a stable solution (defined in materials and methods) is shown in Table 5.

Water-alcohol ratio in solution of inulin and THC % v / v water Alcohol THC 53% max EtOH (ethanol) 62% max n-PrOH (n-propanol) 63% max TBA (t-butanol) Inulin 50% minimum EtOH 60% minimum n-PrOH 60% minimum TBA

Inulin aqueous solution was added to THC solution to prepare a solution for spray drying. It has been demonstrated that the addition must be carried out very quickly to prevent inulin from clouding the mixture. The solution remained clear for the time needed to spray the solution. 690 mg THC was dissolved in 20 mL TBA to prepare a THC solution to be lyophilized. Each 20 mL glass vial was filled with 0.23 mL THC solution. The solution was then diluted with 0.57 mL of pure TBA. After addition of 1.2 mL of aqueous solution of inulin (160 mg / mL), the vials were shaken by hand and immediately frozen.

Recovery of THC After Drying

Immediately after preparation, the amount of THC in the spray dried sample was less than expected. Initially, a recovery of about 50% was observed. After changing both the spray gas stream and the gas flow from the heater to nitrogen, the recovery was increased to 75%. In the case of lyophilization, an estimated 100% THC was found in the sample after the drying process.

Characterization of THC-Containing Samples

Scanning electron microscope

Scanning electron microscopy (SEM) photographs of the spray dried product showed the presence of aggregates of small particles. These particles with a diameter of 1 to 5 μm are hollow. The small size and reduced density of the spray dried particles make them excellent for processing into anhydrous powder formulations for inhalation. SEM pictures of the reference product (inulin without THC, spray dried using the same solvent under the same conditions) showed no difference. THC spots were not indicated on the particle surface of the THC containing sample, indicating that THC was incorporated into the inulin matrix.

Stability of Samples Containing THC

The samples were exposed to conditions of O ₂ or low O ₂ (indicated as nitrogen in the figure) at 20 ° C. and 47 ° C., respectively. In addition, they were exposed to two different humidity at 20 ° C. as summarized above. The spray dried product showed a slight change in color after being collected from the spray dryer.

3 to 6 show the results of batches 12, 5, 6 and 9. The amount of THC was measured. In the figures, the fraction of Δ ⁹ -THC present in the sample after several exposures was plotted for five climates.

The lyophilized sample (batch 12) is shown in FIG. 3. Following the five climates described above, some samples of the batch were exposed to 60 ° C. 0% RH. FIG. 4 shows stability data of spray dried batches from a solution of 1-PrOH and water containing 3.34% THC, FIG. 5 shows a spray drying from a water-1-propanol solution with a higher THC content (7.77%). Indicated batches. 6 shows stability data of spray dried batches from a solution of ethanol and water containing 4.00% THC.

The results from the spray dried batches show that the stability of THC is improved by the formulation. Temperature has the greatest influence on the rate of decomposition. Moisture and oxygen are less important. However, it should be noted that samples stored under nitrogen may be contaminated to some extent with oxygen.

Each figure clearly shows that the stability of the lyophilized product is superior to the physical mixture and pure THC (see FIGS. 7 and 8). Obviously, the method of making the sugar glass greatly affects the stability of the product.

As can be seen in FIG. 5, the degradation of the lyophilized product is minimal under all conditions tested except 60% RH. However, the somewhat lower concentrations found herein may be due to the fact that under these conditions the material decays, making the extraction process less effective.

Reference batch

To test the stabilizing ability of inulin, the data presented above should be compared with batches having the same chemical and physical structure but not containing inulin. This suggests that the reference batch consists of a separate inulin molecule, indeed the vapor of THC. As this is impractical, two different reference-batches are prepared: physical mixture containing about 4% THC and 96% untreated inulin and pure THC. The results are shown in FIGS. 7 and 8, respectively.

It should be mentioned that during the preparation of the physical mixture, a solution of THC in methanol softened the inulin powder to some extent. After evaporation of methanol, a solid thin film of inulin and THC appeared somewhat at the bottom of the vial. The low porosity thin film overprotects the reference material. In addition, some of the THC may be included by mixing the methanolic THC solution with a sugar.

It should be stressed that self-protection is associated with pure THC samples since pure THC samples also form protective thin films.

Claims (19)

Of natural cannabinoid compounds and sugars, sugar alcohols, mixtures of sugars or sugar alcohols, characterized in that the natural cannabinoid compound is incorporated in sugar glass as a single molecule capsule without forming a guest-host complex. A pharmaceutical composition comprising a glass of a mixture. The pharmaceutical composition of claim 1, wherein the sugar or mixture of sugars is a non-reducing sugar or a mixture of non-reducing sugars. The pharmaceutical composition according to claim 1 or 2, wherein the natural cannabinoid compound is Δ ⁹ -tetrahydrocannabinol. The pharmaceutical composition according to any one of claims 1 to 3, wherein the sugar glass has a glass transition temperature of at least 50 ° C under normal environmental conditions. The pharmaceutical composition according to any one of claims 1 to 4, wherein the sugar or mixture of sugars is fructan or a mixture of fructans. 6. The pharmaceutical composition according to claim 5, wherein the fructan or mixture of fructans is inulin or a mixture of inulin, preferably inulin having at least 6 DPs, or a mixture of inulins, wherein each inulin has at least 6 DPs. 7. A pharmaceutical composition according to claim 6, wherein each inulin in the inulin or mixture has a DP of 10 to 30, preferably 15 to 25. The method according to any one of claims 1 to 7, Tablets, capsules, lozenges, enemas, suppositories, products for transdermal administration, powders for pulmonary administration, or for subcutaneous or intramuscular administration, including conventional oral tablets, sublingual tablets, oral tablets, or oral disintegrating or soluble tablets Pharmaceutical compositions in the form of rods or suspending agents. The pharmaceutical composition of claim 8 for oral administration. The pharmaceutical composition of claim 8 for pulmonary administration. a) dissolving the natural cannabinoid compound in an organic solvent soluble in water and dissolving the sugar, sugar alcohol, mixture of sugars or mixture of sugar alcohols in water; b) the dissolved cannabinoid compound and the dissolved sugars, sugar alcohols, mixtures of sugars or mixtures of sugar alcohols are mixed to obtain a sufficiently stable mixture; c) the mixture is lyophilized, spray dried, vacuum dried or super critical dried, so that the natural cannabinoid compound does not form a guest-host complex in the sugar glass as a monomolecular capsule. A method of making a pharmaceutical composition comprising a glass of a natural cannabinoid compound, and a sugar, a sugar alcohol, a mixture of sugars or a mixture of sugar alcohols, which is incorporated. The method of claim 11, wherein the sugar or mixture of sugars is a non-reducing sugar or a mixture of non-reducing sugars. 13. The method of claim 11 or 12, wherein the natural cannabinoid compound is Δ ⁹ -tetrahydrocannabinol. The method of claim 11, wherein the sugar or mixture of sugars is fructan or a mixture of fructans. The process according to claim 14, wherein the fructan or the mixture of fructans is inulin or a mixture of inulin, preferably inulin having at least 6 DPs, or each inulin is a mixture of inulin having at least 6 DPs. The process according to claim 11, wherein the organic solvent is a C ₁ -C ₆ alcohol, preferably C ₂ -C ₄ alcohol. 17. The process of claim 16 wherein the alcohol is selected from the group consisting of ethanol, n-propanol and t-butyl alcohol, preferably t-butyl alcohol. 18. The method of any one of claims 11-17, wherein the pharmaceutical composition is prepared by freeze drying. The tablet, capsule, lozenge, enema, suppository of claim 11, wherein the pharmaceutical composition comprises a conventional oral tablet, a sublingual tablet, an oral tablet, or an orally disintegrating or soluble tablet. And further processing into a transdermal administration product, a pulmonary administration powder, or a rod or suspension for subcutaneous or intramuscular administration.