Guidelines for quality control of medical cannabis

Abstract

Quality control (QC) of cannabis helps ensure safety, quality and efficacy of cannabis preparations for medicinal use. The aim of the study was to compare QC tests related to the production of medicinal cannabis in different countries. Focus was placed on tests required to determine cannabinoids, terpenes, mycotoxins, pesticides and heavy metals in cannabis. Countries where the use of medical cannabis is legalised and the respective regulatory frameworks were identified. QC tests for medical cannabis required in different countries were compared. Focus was given to (i)potency testing, (ii)testing for terpenes, and (iii)limits of heavy metals, pesticides and mycotoxins. Local regulatory guidelines related to QC of medical cannabis were reviewed and updated. Twenty-six countries which legalised cannabis for medicinal use were identified: Denmark, Germany, Switzerland, the Netherlands and the United States (US) have set up monographs for medical cannabis. The German monograph stipulates limits for allowed concentrations of ∆-9-tetrahydrocannabinol (THC) and Cannabinol (CBN), whereas Switzerland only specifies the maximum limit of CBN. Malta has a list of approved products, each with specific allowed concentrations of THC and CBD and no limits are mentioned with respect to CBN. Germany, Malta and Switzerland follow the QC limits set by the European Pharmacopoeia, for allowed concentrations of Heavy Metals Cadmium: 1.0ppm, Lead: 5.0ppm, and Mercury: 0.1ppm, Pesticides such as Diazinon: 0.5ppm, and Mycotoxins where the sum of the allowed concentrations of Aflatoxin B1, B2, G1 and G2 is 4mcg/kg. The Netherlands’ monograph follows the European Pharmacopoeia for allowed concentration of mycotoxins and pesticides, but has different limits for heavy metals: Cadmium 0.5ppm, Lead 20.0ppm and Mercury 0.5ppm. The US monograph does not specify limits for cannabinoid concentrations as these vary according to state. Limits are set for Heavy Metals: Cadmium 0.3ppm, Lead 0.5ppm, Mercury 0.1ppm and Arsenic 0.2ppm. Pesticide limits vary from one state to the other in the US. With regards to Aflatoxins, the limits set by the US for the sum of Aflatoxin B1, B2, G1 and G2: 20ppm are higher than the limits set by the European Countries and Australia. In the US Aflatoxin concentration limits also vary according to the state. Harmonisation is present between countries with regards to QC parameters of mycotoxins, pesticides and most heavy metals, but not for the established limits of the cannabinoid concentrations.