Methods for preparing cannabinoids

Abstract

The pharmaceutical industry is highly regulated to ensure the safety, efficacy, and quality of medicines, and discoloration of medicines is one of the major causes of drug recalls. It is an object of the present invention to provide an improved method for producing stable, substantially pure cannabinoids for use in medicines. The use of such stable, substantially pure cannabinoids in medicines will improve patient compliance with medication. The main steps of this method are decarboxylation, extraction, winterization, and crystallization.

Description

[Technical Field]

[0001] The present invention relates to a method for preparing stable and substantially pure cannabinoids, which can be used as active ingredients in pharmaceutical formulations. [Background technology]

[0002] The pharmaceutical industry is highly regulated to ensure the safety, efficacy, and quality of medicines, as well as the relevance and accuracy of product information. Drug regulators and manufacturers are increasingly examining the role of product appearance and physical characteristics in ensuring the safe and appropriate use of medicines. There is concern that interchangeable medicines that differ in physical appearance, such as different size, color, and shape, may lead to medication errors or reduce consumer acceptance of prescribed treatments, potentially impairing patient compliance.

[0003] Drug discoloration is one of the leading causes of drug recalls (Ahuja S. & Dong M. Elsevier, February 9, 2005, "Handbook of Pharmaceutical Analysis by HPLC"). Discoloration refers to a change in the color of a dosage form from its specified appearance. It can occur as a result of cross-contamination during the manufacturing process or during the transportation, distribution, and / or storage of a drug product. Drug product discoloration can affect the drug product's potency, degradation products, and impurities, so a drug product should be recalled when discoloration occurs and the chemical causing the discoloration is identified.

[0004] Cannabinoids have been widely described in the past for their medicinal use to treat various health conditions. In recent years, cannabinoid-based medicines have become increasingly available to patients in many countries as pharmaceutical products. There are currently four types of cannabinoid-based pharmaceutical products available on the market: These are dronabinol (Marinol®), a synthetic tetrahydrocannabinol (THC) used to treat loss of appetite in patients with AIDS and chemotherapy-induced nausea and vomiting; nabilone (Cesamet®), a synthetic cannabinoid and THC analogue used to treat chemotherapy-induced nausea and vomiting; nabiximol (Sativex®), a complex botanical mixture containing THC, CBD, and other plant-derived cannabinoids and non-cannabinoids, approved in Europe for the treatment of symptom improvement in adult patients with moderate to severe spasticity due to multiple sclerosis; and cannabidiol (Epidiolex®), a plant-derived, purified CBD-containing cannabidiol approved in the United States for the treatment of seizures associated with Lennox-Gastaut syndrome, Dravet syndrome, or tuberous sclerosis complex in patients 1 year of age and older.

[0005] Epidiolex was developed to provide treatment for seizures associated with Lennox-Gastaut syndrome (LGS) and Dravet syndrome (DS), characterized by seizures considered resistant to one or more antiepileptic drugs (AEDs). (See WO 2019 / 97238 and WO 2016 / 203239.) The drug product contains plant-sourced CBD purified to achieve a specific cannabinoid profile that allows for greater therapeutic efficacy compared to synthetic preparations of CBD free of minor cannabinoid impurities and crude extracts with high levels of minor cannabinoid impurities. This requires carefully controlled preparation and purification methods to comply with the drug product specifications. WO 2019 / 207319 demonstrates the importance of using plant-sourced cannabis for purification instead of simply using crude extracts.

[0006] Due to the modern uses of cannabinoids in medicine outlined above, there has been a need to find more effective ways to produce these cannabinoids, particularly in a stable form that exhibits a consistent appearance and impurity profile.

[0007] The standard method for preparing CBD for use in pharmaceuticals is shown on the left side of Figure 1. Briefly, the method involves decarboxylation of crushed CBD plant material (BRM), followed by extraction with liquid CO2 to produce a crude CBD extract. This crude extract is then winterized to produce a purified extract, which is itself crystallized to produce the CBD active pharmaceutical ingredient (API). Thus, the standard method requires the isolation of two types of CBD extract: a crude extract and a purified extract.

[0008] This method is described in more detail in U.S. Patent No. 10,583,096. The dried, ground BRM is decarboxylated by heating to approximately 150°C in a decarboxylation stirred pan (DAP), converting the cannabidiolic acid (CBDA) naturally present in the plant into active CBD. It is then extracted with liquid CO2 at 60 bar / 10°C to produce a crude CBD extract containing approximately 60%-80% w / w CBD. The remainder of the extract is made up of various impurities, including other cannabinoids, long-chain alkanes, terpenes, sterols, and triglycerides. Further methods for purifying and characterizing CBD preparations are disclosed and described in GB Patent Nos. 2,548,873 and 2,574,321.

[0009] Winterization involves precipitation of long-chain waxy alkane impurities from a 2.0-volume solution of the crude extract in ethanol. This is accomplished by cooling to approximately -20°C over 50 hours in a freezer or by cooling to -15°C to -25°C over 4 hours using a temperature-controlled unit. The precipitate is then removed by filtration. Removing the last traces of ethanol from the extract can be difficult and time-consuming. Ethanol levels above 3% w / w in the purified extract can significantly impact crystallization yield. Due to the manageability of evaporator capacity and scale, the extraction batch must be split for winterization, creating a bottleneck in the CBD production process.

[0010] Crystallization is performed from the isolated purified extract. CBD API is crystallized from the refined (hot-filtered) extract in 2.0 volumes of n-heptane. 0.1% w / w crystalline CBD is seeded at 12°C. After waiting 2 hours for the seed to begin to precipitate (grow), the suspension is cooled very slowly (over 24 hours) to -18°C to -20°C. The suspension is stirred at -18°C to -20°C for an additional 24 hours to generate a yield before filtration. The filtered solid is washed with a short slurry and displacement wash (at -18°C to -20°C and 10°C), 4 x 0.25 volumes of solvent for 30 minutes, followed by a 1.0 volume reslurry at 10°C, for a total of 2.0 volumes of heptane wash solvent. The washed API is dried in an agitated filter dryer at 20°C to 30°C. Therefore, the overall crystallization process is very long and there is a need to improve the process efficiency to produce high purity and high stability CBD, and simpler and more efficient washing methods are required.

[0011] Many publications have discussed the issue of cannabinoid discoloration.

[0012] U.S. Patent No. 10,155,176 discloses a method for producing a cannabinoid product optionally containing an array of terpenes, flavonoids, and other plant components. It specifically discloses the use of an adsorption and filtration system without winterization or crystallization. It describes a pretreatment with an adsorbent to remove impurities from a cannabinoid-containing extraction feedstock. One such impurity discussed is chlorophyll, which, when removed from the feedstock, improves flavor and produces a lighter-colored final product. The resulting cannabinoid product contains 30% to 95% cannabinoids. Stability testing is not disclosed or mentioned.

[0013] U.S. Patent No. 10,604,464 discloses a crude cannabinoid extract that is green due to the presence of chlorophyll, which is removed using a decolorization zone, changing the color of the extract from green to amber. This adds an extra step to the manufacturing process, reducing process efficiency. The document provides no data regarding the long-term stability of the resulting composition, nor does it provide short-term stability data.

[0014] There are commercially available filter aids, such as Florisil®, that are marketed to remove pesticides from cannabis. It provides examples of various pesticides that have been removed from cannabis extracts, such as acephate, acetamiprid, etc. Again, no data is disclosed regarding the stability of cannabinoids or purity levels with the use of such filter aids.

[0015] Clearly, there is a need for more efficient and streamlined methods for producing stable, substantially pure cannabinoids for use in pharmaceuticals. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] International Publication No. 2019 / 97238 [Patent Document 2] International Publication No. 2016 / 203239 [Patent Document 3] International Publication No. 2019 / 207319 [Patent Document 4] U.S. Patent No. 10,583,096 [Patent Document 5] British Patent No. 2548873 [Patent Document 6] British Patent No. 2574321 [Patent Document 7] U.S. Patent No. 10,155,176 [Patent Document 8] U.S. Patent No. 10,604,464 [Non-patent literature]

[0017] [Non-Patent Document 1] Ahuja S. & Dong M. Elsevier, February 9, 2005, "Handbook of Pharmaceutical Analysis by HPLC" [Non-patent document 2] Handbook of Cannabis, Roger Pertwee, Chapter 1, pp. 3-15 Summary of the Invention [Problem to be solved by the invention]

[0018] It was an object of the present invention to provide an improved method for producing cannabinoid-containing drug products that would provide good stability of cannabinoid activity to make drug development feasible. [Means for solving the problem]

[0019] According to a first aspect of the present invention, a) decarboxylation step, b) an extraction step to produce a crude extract; and c) a combined dewaxing and crystallization process, the sub-steps being: i) precipitating the alkanes in the solvent by cooling and removing them by filtration; ii) the substep of removing the solvent by partial distillation; iii) a substep of solvent exchange with heptane; iv) removing the remaining solvent by aqueous phase separation to obtain a heptane solution; v) heating the heptane solution and filtering it; vi) cooling the solution under constant stirring; vii) a sub-step of adding crystal seeds to the solution and growing the crystal seeds to obtain a suspension; viii) cooling, stirring, filtering and washing the suspension to obtain the product; and ix) deliquorization and drying of the product; a process comprising: The present invention provides a stable, substantially pure cannabinoid obtained by a method comprising:

[0020] Preferably, the cannabinoid may be selected from the group consisting of cannabichromene (CBC), cannabichromene acid (CBCV), cannabidiol (CBD), cannabidiolic acid (CBDA), cannabidivarin (CBDV), cannabidiol-C1 (CBD-C1), also known as cannabidiolcol, cannabidiol-C4 (CBD-C4), also known as nor-cannabidiol, cannabidiol-C6 (CBD-C6), cannabigerol (CBG), cannabigerol propyl variant (CBGV), cannabicyclol (CBL), cannabinol (CBN), cannabinol propyl variant (CBNV), cannabidiol (CBO), tetrahydrocannabinol (THC), tetrahydrocannabinolic acid (THCA), tetrahydrocannabivarin (THCV), and tetrahydrocannabivarinic acid (THCVA).

[0021] More preferably, the cannabinoid is cannabidiol (CBD).

[0022] In a further embodiment of the invention, the extraction step is carried out using liquid CO2 at a temperature of 25°C and a pressure of 100 bar.

[0023] Preferably, the dewaxing step uses methanol as the solvent.

[0024] Preferably, the winterization step is carried out at a temperature between 0°C and 5°C.

[0025] Preferably, the aqueous phase separation consists of less than three aqueous washes.

[0026] In a further aspect of the invention, the dewaxing step uses a vanadium-free filter aid.

[0027] Preferably, the winterization step uses an alternative filter aid.

[0028] Alternatively, the winterization process does not use a filter aid.

[0029] In a further aspect of the invention, a chelating agent is used in the solvent exchange.

[0030] Preferably, the chelating agent is citric acid.

[0031] In a further aspect of the invention, one or more antioxidants are added.

[0032] Preferably, the one or more antioxidants are citric acid or ascorbyl palmitate.

[0033] In a further embodiment of the invention, the CBD has a purity of >95%, preferably greater than 96% (w / w), more preferably 97% (w / w), even more preferably 98% (w / w), and most preferably 99% (w / w) or greater.

[0034] Preferably, THC is present at less than 0.15%.

[0035] Preferably, CBDV is present at a maximum of 1%.

[0036] According to a second aspect of the present invention, a) decarboxylation of cannabidiol (CBD) plant material; b) extracting the reaction mixture of step (a) to produce a crude extract; and c) a combined dewaxing and crystallization process of the crude extract of step (b), comprising the following sub-steps: i) a sub-step of precipitating the alkanes in the solvent of the crude extract of step (b) by cooling and removing the alkanes by filtration; ii) removing the solvent of the reaction mixture of substep (i) by fractional distillation; iii) solvent-exchanging the reaction mixture of substep (ii) into heptane; iv) removing residual solvent from the reaction mixture of substep (iii) by aqueous phase separation to obtain a heptane solution; v) heating the heptane solution of substep (iv) and filtering it; vi) cooling the reaction mixture of substep (v) under constant stirring; vii) a sub-step of adding crystal seeds to the reaction mixture of sub-step (vi) and growing the crystal seeds to obtain a suspension; viii) cooling, stirring, filtering and washing the suspension of substep (vii); and ix) deliquoring and drying the reaction material of substep (viii) to obtain stable, substantially pure cannabinoids; a process comprising: A method is provided that includes:

[0037] Embodiments of the present invention are further described below with reference to the accompanying drawings. [Brief explanation of the drawings]

[0038] [Figure 1] FIG. 10 shows a graphical comparison of the unabbreviated and abbreviated methods. [Figure 2] FIG. 1 shows a plot of total alkane levels in winterized extract after winterization at various temperatures. [Figure 3] FIG. 1 shows a plot of % w / w residual methanol remaining in a heptane solution after successive aqueous washes. [Figure 4] Figure 1 shows the appearance of the drug product from Method A relative to the drug product from Method B after 2 and 55 days. The API batches formulated into the drug product were 800346990 and 800347540, representing Method A (control), and batches 800342580 and 800340900, representing Method B. [Figure 5] FIG. 1 shows a 3-D scatter plot of the aggregate results showing the color change of drug products from Method A and Method B over a 55-day period. Significant differences in trends are observed between the two different drug products. [Figure 6] The graph shows the elemental analysis results for the trace metals iron, aluminum, magnesium, and vanadium. The yellow boxes represent Method A API and the shortened method without filter aid API, the green boxes represent the shortened method API with celite filter aid, and the red boxes represent the representative shortened method API. [Figure 7] Figure 1 shows the appearance of high and low vanadium addition experiments compared to the positive and negative controls of Methods A and B during the addition experiment. The lower addition vanadium oxide follows the color change of the Method B control over 14 days. [Figure 8] Chromatograms showing impurity growth at RRT 0.79 in the Method B control and low-loading vanadium oxide in the spiked experiment. The impurity peak is circled in red. [Figure 9] FIG. 1 shows a 3-D scatter plot of colorimetric results for filter aid-free API compared to abbreviated method API and control Method A API. [Figure 10] FIG. 1 shows the drug product obtained using alternative filter aids at the first time point (day 0) and second time point (day 7). [Figure 11] FIG. 1 shows the appearance of batches at 25° C. and 40° C. at the initial time point and after 7, 14, 21, 28, 56, 84, and 168 days. [Figure 12]FIG. 1 shows CBD assay results for all three Method B filter aid-free batches at 25° C. and 40° C. from Example 4. [Figure 13] FIG. 1 shows the total degradate results for all three Method B filter aid-free batches at 25° C. and 40° C. from Example 4. [Figure 14] FIG. 1 shows the b* values ​​from a colorimetric test at 40° C. comparing the trends of three Method B no filter aid batches versus Method A batches. The b* value is blue or yellow based on opponent color theory. [Figure 15] FIG. 1 shows total degradant results at 40° C. comparing trends for three Method B no filter aid batches versus Method A batches. [Figure 16] FIG. 1 shows a 3-D scatter plot of colorimetric results of drug products manufactured under various conditions used to test various chelating agents, citric acid, and EDTA. [Figure 17] FIG. 17 shows the impurity profile and percentage of CBD present in a drug product manufactured under the same conditions as FIG. 16. [Figure 18] FIG. 1 shows the percentage of degradants present at three different time points when five different antioxidants are used. [Figure 19] Photographs of CBD gel at the initial time point and after 27 days with different antioxidants. DETAILED DESCRIPTION OF THE INVENTION

[0039] definition Definitions of some terms used to describe this invention are set out below.

[0040] A "substantially pure" cannabinoid is defined as a cannabinoid present at a purity of greater than 95% (w / w), more preferably greater than 96% (w / w), more preferably 97% (w / w), more preferably 98% (w / w), and most preferably 99% (w / w) or greater.

[0041] "Method A" is used to describe the standard, unabbreviated method.

[0042] "Method B" is used to describe the shortened method of the present claims.

[0043] "Alternative filter aid" is used to describe the following filter aids: Harborlite 800 (Fisher) and Celpure (Imerys Filtration).

[0044] The cannabinoids described in this application are listed below with their standard abbreviations.

[0045] [Table 1A]

[0046] [Table 1B]

[0047] [Table 1C]

[0048] Active Pharmaceutical Ingredients There are many known cannabinoids, and the method of the present invention can be used to produce stable, substantially pure cannabinoids. Such cannabinoids may be selected from the group consisting of cannabichromene (CBC), cannabichromene acid (CBCV), cannabidiol (CBD), cannabidiolic acid (CBDA), cannabidivarin (CBDV), cannabidiol-C1 (CBD-C1), also known as cannabidiol, cannabidiol-C4 (CBD-C4), also known as nor-cannabidiol, cannabidiol-C6 (CBD-C6), cannabigerol (CBG), cannabigerol propyl variant (CBGV), cannabicyclol (CBL), cannabinol (CBN), cannabinol propyl variant (CBNV), cannabiditriol (CBO), tetrahydrocannabinol (THC), tetrahydrocannabinolic acid (THCA), tetrahydrocannabivarin (THCV), and tetrahydrocannabivarinic acid (THCVA). This list is not exhaustive and merely details the cannabinoids identified in this application for reference. To date, over 100 different cannabinoids have been identified, and these cannabinoids can be divided into different groups: phytocannabinoids, endocannabinoids, and synthetic cannabinoids.

[0049] The method according to the invention may also be used to produce stable, substantially pure cannabinoids as disclosed in Handbook of Cannabis, Roger Pertwee, Chapter 1, pages 3-15.

[0050] Thus, the method according to the present invention can be used to produce all cannabinoids, but is exemplified using CBD.

[0051] extraction The extraction efficiency of decarboxylated CBD BRM was improved by increasing the bulk density by pelleting and grinding the material prior to decarboxylation. This increase in bulk density allowed for a higher loading mass while reducing the total amount of CO2 per kg of BRM, resulting in a higher yield of CBD extract. One full-scale batch derived from pelleted BRM and extracted using 55 kg CO2 / kg of decarboxylated BRM yielded good extraction efficiency (approximately 90%) and high product assay (74%). Extraction efficiency was improved by increasing the temperature and pressure (from 60 bar, 10°C to 100 bar, 25°C).

[0052] Shortened dewaxing and solvent exchange Alkane impurities precipitate (winterization) from a 2.0 volume solution of the crude extract in methanol upon cooling to 0-5°C. Methanol is removed by partial distillation, and after solvent exchange into n-heptane, the remaining methanol is removed by aqueous phase separation (water wash) (see Figure 1).

[0053] Dewaxing solvent In head-to-head winterization experiments (2.0 vol, 60 min, 20°C), methanol winterization was comparable to ethanol winterization, with both solvents yielding low levels of alkanes (0.03% w / w) in the purified extract (see Table 2). Methanol is easily removed by distillation and aqueous separation (washing) after winterization, minimizing its impact on crystallization yield.

[0054] Experiments were performed on 20 g of extract and purified material at room temperature for 1 hour. Following filtration, samples were taken from the filtrate for alkane analysis. Results showed that in both cases, alkane levels were very low even after 1 hour of stirring at room temperature, significantly shorter than Method A. These solutions were distilled to dryness to isolate the purified extract, and crystallization was performed. The isolated material was then analyzed for alkane levels. Table 2 shows the alkane content obtained by chromatography of the batch solution before crystallization and the isolated final product thereafter.

[0055] [Table 2]

[0056] Data showed that methanol was a more efficient solvent for removing alkanes. Analysis of the final product showed low levels of isolated materials from ethanol refining, but the levels from methanol refining were also very low, making methanol preferable for plant production due to its low cost and large supply.

[0057] Dewaxing Temperature A series of winterization experiments were conducted at various temperatures and filtered through a liquid bag filtration system (GAF® Bag) at the experimental winterization temperature. Low levels of alkanes were obtained in all purified extract samples (<0.25% w / w). The lowest alkane levels were obtained from winterization at 0°C to 5°C (see Figure 2).

[0058] Alkane cake washing After filtering the methanol solution, the alkane cake was washed with cold (0°C to 5°C) methanol to remove any retained traces of CBD. Filtration of the liquid was reported to be faster when the 2.0 volume wash solvent was divided into 0.5 volume washes (as opposed to a single larger wash). Each wash was added to the alkane before the cake dried and cracked.

[0059] filter aid A filter aid was used to aid in the filtration of the alkane as it significantly reduced filtration time, especially on a large production scale.

[0060] Solvent exchange After winterization, methanol was effectively removed by partial distillation and partitioning into an aqueous phase (water wash). After distillation, the methanol solution was solvent-switched into n-heptane and vigorously mixed with 2.0 volumes of purified water. The aqueous layer (containing methanol) was separated from the organic phase and removed. This typically resulted in very low levels of methanol in the resulting heptane solution, which was carried forward to the crystallization step. Methanol was shown to have reduced to levels of <0.5% w / w after the second aqueous wash and to very low levels after the third wash (see Figure 3). This suggested that three aqueous washes were more than sufficient.

[0061] Improved Crystallization To improve process efficiency, an improved crystallization method was proposed. The cooling time (from the seeding temperature to the isolation temperature of -18°C to -20°C) was successfully reduced from 24 hours to 16 hours without adversely affecting particle size. The stirring time from -18°C to -20°C was reduced from 24 hours to 6 hours without affecting yield. The seed growth time was reduced from 120 minutes to 45 minutes.

[0062] The complexity of the wash method was reduced by eliminating displacement washes. Wash efficiency was further improved by increasing the volume of each individual wash (to achieve better cake wetting). The number of washes was reduced from 5 to 3, maintaining the total wash volume at 2.0 volumes. The improved crystallization method reduced the crystallization time at the plant by approximately 24 hours.

[0063] Discoloration of pharmaceutical products A difference in color was observed in CBD drug products using CBD API manufactured via Method B (truncated) route compared to CBD drug products using CBD API manufactured via Method A (non-truncated) route.

[0064] A stability study was conducted to analyze two Method A and two Method B drug products to evaluate color differences. The Method A results served as a control for evaluating the Method B drug product batches. Conditions were similar to the "in-use" study, in which one screw-cap amber bottle containing the drug product per batch was manufactured, stored at room temperature (laboratory temperature maintained at 20°C ± 5°C to simulate commercial storage), and opened to prepare samples for testing. The same bottle was then reopened at designated time points. Testing was conducted over a 55-day period using visual and colorimetric test methods.

[0065] Initially, both Method A and Method B solutions appeared clear and colorless to yellow. After two days, the Method B solution became significantly more yellow compared to the Method A solution, which remained clear to yellow. See Figure 4. Over time, the Method B solution became a deeper yellow, going from yellow to slightly orange after 55 days. The color change of the Method B solution over this 55-day period is documented in Figure 5.

[0066] Stability results were recorded over 55 days for the Method A drug product (Batch 800347540) shown in Table 3.1 and the Method B drug product (Batch 800340900) shown in Table 3.2. Solution appearance, as well as degradant and CBD concentrations, were recorded using a UPLC (ultra-performance liquid chromatography) assay. The results support the visual findings in Figure 4 and the colorimetric data in Figure 5, which showed that the Method B drug product changed color slightly to orange over 55 days. As can be seen in Table 3.2, a noticeable color change was observed for the Method B drug product starting from day 20, while the Method A drug product remained a clear, colorless to yellow solution (see Table 3.1). Furthermore, THC and total degradant concentrations were found to exceed specification limits for the Method B drug product at days 30 and 55, respectively (see Table 3.2).

[0067] [Table 3]

[0068] [Table 4]

[0069] Filter aids have varying levels of trace elements depending on the manufacturer's specifications. Various API samples, shown in Figure 6, were submitted for elemental analysis. The data show surprisingly high levels of vanadium in the abbreviated Method API, while low levels are present in the Method A API.

[0070] Further screening experiments were conducted using vanadium oxide to assess the potential impact of this element. Highly (100 mg) and low (2 mg) loaded vanadium oxide were spiked into 100 mL of ethanol solution containing 10 g of representative material from Method A. Controls for both Method A and Method B were run as part of the spike experiments. The resulting appearance and impurity profiles from this screening experiment are shown in Figures 7 and 8. Figure 7 shows that the low-vanadium spiked sample matches the color change observed in the Method B material. The chromatogram in Figure 8 shows that the increase in impurities in the low-spiked sample over 14 days matches the increase in impurities in the Method B control. Notably, the same impurity (circled in red) was recorded in both the low- and high-spiked vanadium oxide samples and the Method B control. In the high-spiked vanadium experiment, this impurity was still present at day 0, indicating accelerated degradation due to high levels of vanadium oxide. The data presented here indicate that vanadium, especially at low levels, may be a major contributor to the color change in this study.

[0071] One solution to correct the observed color change was to not use a filter aid in the winterization process. In fact, when no filter aid was used during the shortened process in Figure 9, the color change was suppressed. However, removing the filter aid significantly increased the time required for the filtration process.

[0072] Instead, various filter aids were evaluated to assess their impact on the color of the drug product. Celpure and Harborlite were the preferred options as alternative filter aids, as they were shown to produce drug product appearances similar to those of Method A. See Figure 10 compared to Figure 4.

[0073] The following non-limiting examples are provided to further illustrate the present invention. [Example]

[0074] Evaluation of API without filter aid and with alternative filter aids The API manufactured without filter aid and with alternative filter aids (Celpure and Harborlite) were analyzed and tested against specifications. The API material was analyzed for appearance, CBD assay, and impurity testing performed using a liquid chromatography (LC) TM-170. See Table 4. All API results (four batches without filter aid and two batches with alternative filter aids) show compliance with respect to specification criteria.

[0075] [Table 5]

[0076] [Example]

[0077] Evaluation of APIs manufactured without filter aids and drug products using alternative filter aids Drug products were formulated using API from various manufacturing streams. These streams differed only in the winterization process, specifically the filtration step, and did not use any filter aid or alternative filter aids. The alternative filter aids evaluated were Celpure and Harborlite. Three different batches of API were manufactured using Celpure filter aid, two batches using Harborlite, and four batches without filter aid, and their corresponding drug products were analyzed (see Table 5.1 and Table 5.2). The 7-day stability study indicated whether the drug product performed within specification limits with respect to color and impurity profile. An analysis was also performed at 35 days to confirm the stability of this drug product at ambient conditions over an extended period of time and to reaffirm the stability of the drug product.

[0078] [Table 6]

[0079] [Table 7]

[0080] The above results demonstrate compliance with specifications for CBD manufactured using both the filter aid-free shortening method and the alternative filter aid shortening method. There was no evidence of any difference in specification test results, and therefore, it can be concluded that the changes introduced in the manufacturing process did not adversely affect the quality of the final API. This study demonstrates that the filter aid-free and alternative filter aid drug product met specifications over a 35-day period with respect to color, impurity profile, and stability of this drug product at ambient conditions. [Example]

[0081] Comparability of drug products obtained from Method A and the shortened Method B, which does not use a filter aid. The objective of this stability study was to investigate the stability of drug product from Process B API manufactured without a filter aid and compare it to drug product from Process A API. Additionally, a drug product from Process B API manufactured using Clarcel filter aid was used for comparison.

[0082] Studies were conducted on bottles stored at long-term conditions of 25°C / 60%RH (relative humidity) and accelerated conditions of 40°C / 75%RH. A summary of the stability studies completed to date is shown in Table 6.

[0083] [Table 8]

[0084] The following tests were performed on two filter aid-free Method B batches, a Method A control batch, and a Method B batch with Clarcel filter aid, and the results are shown in Table 7.1 and Table 7.2. ·exterior CBD Assay by UPLC UPLC digest

[0085] [Table 9A]

[0086] [Table 9B]

[0087] [Table 10A]

[0088] [Table 10B]

[0089] The results of the stability study confirmed previous results shown in Table 5, with the drug product from Method B API manufactured without filter aid being within specification limits. Importantly, the drug product from Method B without filter aid was comparable to that from Method A API. Meanwhile, the drug product from Method B API manufactured using Clarcel filter aid was significantly different in appearance and degradation levels from the drug products from Method A and Method B without filter aid. Notably, THC concentrations exceeded specification limits at 84 and 112 days at 25°C (Table 7.1) and after 28 days at 40°C (Table 7.2), while the solution turned deep yellow in appearance at the aforementioned time points.

[0090] conclusion Results out to 112 days (16 weeks) show that the Method B batches without filter aid were equivalent to the Method A batches in terms of appearance, CBD, and degradant concentration at both 25° C. and 40° C. Thus, these results demonstrate that the Method B drug product without filter aid retains the same quality, purity, and stability as the Method A drug product over an extended period of time. [Example]

[0091] Stability of drug products obtained from abbreviated method B without using filter aids The objective of this stability study was to investigate the long-term (6-month) stability of drug product from Method B API manufactured without a filter aid. Testing was performed on bottles stored at long-term conditions of 25°C / 60% RH and accelerated conditions of 40°C / 75% RH.

[0092] A summary of the stability studies completed to date is shown in Table 8.

[0093] [Table 11]

[0094] The following tests were performed on three filter aid-free Method B batches, and the results are shown in Table 9.1 and Table 9.2, and Figures 11-15. ·exterior ·Colorimetric analysis CBD Assay by UPLC UPLC digest

[0095] [Table 12]

[0096] [Table 13]

[0097] At 25°C storage conditions, all results were in compliance with the specification acceptance criteria of a clear, colorless to yellow solution after 168 days (see Figure 11). There was no significant change in appearance over the test period.

[0098] At the 40°C accelerated condition, all results were in compliance with the specification acceptance criteria of a clear, colorless to yellow solution after 24 weeks. There was no significant change in appearance over the test period. The batches were slightly darker yellow at each time point compared to the 25°C condition. This was an expected observation, as this was observed with drug product manufactured using Method A.

[0099] As can be seen from Figures 12 and 13 and Tables 9.1 and 9.2, neither the CBD content nor the other cannabinoids changed significantly over the six month period. Furthermore, comparison of the Method B no filter aid batches with the Method A batches at accelerated conditions of 40°C showed little to no deviation in the b* values ​​(see Figure 14) or total degradants (see Figure 15).

[0100] conclusion All results were within their specification limits after 24 weeks and did not change significantly over the study period. All results and trends were comparable to the stability results for drug product manufactured using Method A. [Example]

[0101] Addition of chelating agents To further optimize filter aid-free Method B, it was investigated whether the addition of a chelating agent within the cleaning regime could further reduce trace element contamination while maintaining the appearance of the drug product of filter aid-free Method B.

[0102] Citric acid was compared to EDTA as a potential chelating agent over a 14 day period under the following conditions: Citric acid (API filter aid cleaning) Citric acid (API filter aid-free cleaning) Citric acid (Method B filter aid, solvent exchange) Citric acid (Method B, no filter aid, solvent exchange) EDTA (API filter aid-free cleaning) Method B Filter Aid Method B: No filter aid Method A Control The colorimetric data of the API and drug product manufactured in was recorded and the results are shown in Figure 16.

[0103] The concentrations of various impurities and CBD were also measured (except for the Method A control), and the results are shown in Figure 17.

[0104] Surprisingly, the addition of a citric acid wash during the solvent exchange process in Method B (no filter aid) was found to be beneficial in reducing degradant levels. This is evidenced by the impurity profiles shown in Figure 17, particularly the profile for RRT 0.76 (purple line). The colorimetric data also confirmed that the addition of a citric acid wash did not alter the appearance of the drug product, as shown by the similar colorimetric profiles of "Method A Control" and "Citric Acid (Method B Solvent Exchange No Filter Aid)."

[0105] conclusion Overall, it was concluded that the addition of citric acid as a chelating agent in the solvent exchange is useful in further reducing impurities and degradants from the drug product. [Example]

[0106] Addition of antioxidants Further optimization was performed to test whether the addition of antioxidants would reduce degradants present in the drug product. The antioxidants tested are listed in Table 10. Samples were stored at 60°C and evaluated by chromatography.

[0107] In this example, CBD-C4 was used, but it should be understood that any cannabinoid can be used.

[0108] [Table 14]

[0109] The results of the antioxidant test are shown in Figure 18. At 27 days, the most effective antioxidant was ascorbyl palmitate with 0.39% degradates as a % of activity, and at 54 days, citric acid was the most effective antioxidant with 1.05% degradates as a % of activity.

[0110] conclusion Results up to 54 days indicate that the addition of citric acid and / or ascorbyl palmitate as antioxidants can be beneficial in maintaining a low rate of degradants in the drug product. [Example]

[0111] Further stability studies with antioxidants A series of CBD gels were prepared and both color and degradation (by HPLC) were investigated under forced degradation conditions.

[0112] method A 33% CBD gel was formulated with various antioxidants and subjected to forced degradation conditions (60°C). The various antioxidants used were: alpha-tocopherol, EDTA, sodium metabisulfite, BHA, citric acid, ascorbyl palmitate, and monothioglycerol. The color of the gel was monitored throughout the forced degradation period, as well as analytical profiling to identify the impurity RRT corresponding to the color change.

[0113] Ten grams of 33% CBD gel was prepared using various antioxidants (see Table 11). From the bulk, 0.5 gram aliquots were placed in 20 ml scintillation vials and placed in a (60°C) oven. At various time points, samples were removed and physically and chemically tested. All chemical analyses were performed by HPLC analysis of the CBD gel formulation in hard gelatin capsules.

[0114] [Table 15]

[0115] result physical analysis The data shown in Figure 19 demonstrates the color change of CBD gels depending on the antioxidant present in the formulation. The data show that gels formulated with the antioxidants alpha tocopherol, EDTA, sodium metabisulfite, and BHA (batches B1-B4) developed a dark brown / purple color. Formulations with ascorbyl palmitate and citric acid present (batches B5 and B6) remained yellow after 28 days.

[0116] chemical analysis The data shown in Table 12 below demonstrates that there are no degradants in the formulation at the initial time point. The only peaks present are CBDV, CBD-C4, and CBD.

[0117] [Table 16]

[0118] The data presented in Table 13 show that at 27 days, degradants RRT 0.544, RRT 0.561, RRT 0.599, RRT 0.877, RRT 1.236, and RRT 1.281 were present in the formulation containing alpha tocopherol, EDTA, sodium metabisulfite, BHA, and monothioglycerol. The citric acid and ascorbyl palmitate formulation was found to be free of these degradants. Both formulations (see Figure 19) maintained their original yellow color and did not deteriorate to a dark brown / purple color.

[0119] [Table 17]

[0120] conclusion Various antioxidants were studied under accelerated conditions (as part of a CBD gel formulation) and visually tested for color and degradation by HPLC. Various antioxidants did not significantly suppress color and the associated increase in various impurities.

[0121] Ascorbyl palmitate and citric acid showed significant differences with the color intensity produced in the formulations clearly minimized and significantly more significant impurities not detectably present.

[0122] Overview of the shortened method B (post-extraction process) 1. Dissolve the unpurified CBD extract in 2.0 volumes of methanol at 50°C. 2. Stir the mixture at 0°C to 5°C for 60 minutes to precipitate waxy impurities. 3. The waxy impurities are filtered under vacuum and the resulting cake is washed with 3 x 0.5 volumes of cold methanol to remove traces of retained CBD. 4. Distill the methanol solution to a solution volume of 1.5 volumes. 5. Heptane is added to the concentrated solution according to the experimental concentration required for crystallization (2.2 volumes). 6. Wash the solution with 3 x 2.0 volumes of purified water and separate the aqueous phase containing methanol. IPC confirms that the residual methanol content is within specifications. 7. Heat the washed heptane solution to 50°C, hot filter (refine) to remove undissolved particles, and wash with 0.3 volumes of heptane (total of 2.0 volumes of heptane). 8. Cool the solution to 25°C, then slowly cool to 12°C (over 6 hours). 9. During crystallization in the small plant, maintain an agitation speed of 115 rpm (or equivalent if in a separate vessel). 10. Seed the solution with 1.0% w / w crystalline CBD and allow the seed to grow for 180 minutes (3 hours). 11. Cool the suspension to -18°C to -20°C over 960 minutes (16 hours), then stir at -20°C for 360 minutes (6 hours). 12. Filter the suspension under vacuum and then wash with three heptane washes (3.0 vol total). 2 x 0.75 volume displacement washes at -18°C and 10°C 1 x 1.5 vol, reslurried at 10°C for 30 minutes 13. The product is deliquified and then dried under vacuum at 20°C to 30°C until the residual heptane specification is met. The volumes and concentrations listed above should be relied upon as representative values ​​only. Different scales require adjustments accordingly.

[0123] Overall conclusion API produced without the use of a filter aid or with an alternative filter aid in abbreviated method B demonstrates compliance with respect to specification criteria. Drug products produced without a filter aid and the abbreviated method with an alternative filter aid also meet specifications for color, impurity profile, and stability. Importantly, this drug product was found to be comparable to the drug product produced from control method A over a range of temperatures and over an extended period of time.

[0124] The addition of chelating agents such as citric acid and antioxidants such as citric acid and ascorbyl palmitate can further improve the impurity profile of the drug product.

[0125] It can therefore be concluded that the method outlined above is more efficient and streamlined than previously described methods and is capable of producing stable and substantially pure cannabinoids for use in pharmaceuticals.

Claims

1. In the following order: a) decarboxylation of cannabidiol (CBD) plant material; b) extracting the reaction mixture of step (a) to produce a crude extract; and c) A combined winterization and crystallization process of the crude extract of step (b), comprising the following sub-steps: i) precipitating the alkanes from the crude extract of step (b) in methanol by cooling and removing the alkanes by filtration; ii) removing methanol from the reaction mixture of substep i) by fractional distillation; iii) a substep of solvent exchange of the reaction mixture of substep ii) with heptane; iv) removing the remaining methanol from the reaction mixture of substep iii) by aqueous phase separation to obtain a heptane solution; v) heating the heptane solution of substep iv) and filtering it; vi) cooling the reaction mixture of substep v) under constant stirring; vii) a sub-step of adding crystal seeds to the reaction mixture of sub-step vi) and growing the crystal seeds to obtain a suspension; viii) cooling, stirring, filtering and washing the suspension of sub-step vii) to obtain the product; and ix) deliquoring and drying the product of substep viii) to obtain a stable, substantially pure cannabidiol (CBD); a process comprising: A method for producing stable, substantially pure cannabidiol (CBD), comprising:

2. The extraction process is carried out using liquid CO at a temperature of 25°C and a pressure of 100 Barg. 2 2. The method as defined in claim 1 or the method as claimed in claim 1, wherein the method is carried out using

3. 3. The process according to claim 1 or 2, wherein the winterization step (step c) i)) is carried out at a temperature between 0°C and 5°C.

4. 4. The process according to any one of claims 1 to 3, wherein the aqueous phase separation (step c) iv)) consists of two or three aqueous washes.

5. 5. The method of claim 1, wherein the dewaxing step uses a vanadium-free filter aid.

6. 5. The method of claim 1, wherein the winterization step uses a filter aid selected from Harborlite 800® and Celpure®.

7. 5. The method of claim 1, wherein the winterization step does not use a filter aid.

8. 8. The method of claim 7, wherein a chelating agent is used for solvent exchange.

9. 9. The method of claim 8, wherein the chelating agent is citric acid.

10. 10. The method according to any one of claims 1 to 9, wherein one or more antioxidants are added.

11. 11. The method of claim 10, wherein the one or more antioxidants is citric acid or ascorbyl palmitate.

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