Cannabis olive oil: comparison among different preparation methods

The therapeutic properties of Cannabis sativa are widely recognized nowadays. Due to an increasing interest and the lack of authorized medicinal products, Italian pharmacists are involved in compounding Cannabis magistral preparations, mostly based on the olive oil extraction of cannabinoids from inflorescences. The main extracted components are Delta9-tetrahydrocannabinol (THC) and cannabidiol (CBD), and their corresponding acid, THCA and CBDA. A compendial standardized procedure is not yet available, so methods proposed in scientific literature are followed to prepare Cannabis olive oils [1-4]. The methods most frequently used are four, all based on maceration of vegetable materials in olive oil at high temperature. Two methods [1,2] don’t involve a preliminary decarboxylation, step required to convert THCA and CBDA, molecules pharmacologically less active, into THC and CBD, the active neutral compounds. Decarboxylation can be obtained heating the plant materials at a temperature above 100°C before maceration in olive oil [3] or by sonication [4]. Aim of this work is to evaluate the Efficiency of Extraction (E.E.) of THC and CBD total contents in Cannabis olive oils compounded in the Italian pharmacies, using four Cannabis varieties (Table 1) and following four different preparation conditions [1-4]. Over 3000 samples were analyzed in 2017 and 2018. The E.E. was calculated considering the standardised cannabinoid total content declared in the data sheet of each variety versus the same data obtained in analyzed samples. Cannabis olive oils are prepared with the recommended ratio cannabis/solvent 1g/10 mL (Table 1). Due to the very low content (less than 0.2% w/w), CBD in Bedrocan and THC in Bedrolite was not considered. The E.E. of total THC and CBD in all Cannabis varieties and for any preparation method resulted quite similar, slightly higher for CBD (almost always over 80%) than for THC (less than 75%). In case of varieties with similar CBD and THC content, Bediol and FM2, homogeneous E.E. values were observed. High variability was observed for the methods without decarboxylation (1,2). In conclusion, independently by the used method, cannabinoid extraction is never complete, but probably it can be further improved using a standardized preparation procedure.