Method development and validation for the analysis of medicinal cannabis products, aimed at developing a safety profile for South Africa

Abstract

In the last few years, there has been an increase in the use of cannabis-based products for medicinal purposes. The preparation procedure, however, has not been standardised but is decided by the individual groups of scientists globally. As cannabis-based products are more frequently used for medicinal and recreational uses, standardised quality control methods must be developed, validated and harmonised. This study relates to the three major quality control parameters of interest in cannabis-based products in South Africa. These three quality control tests include cannabis potency, residual solvent residues and heavy metal residues. For cannabis potency a total of 840 samples were analysed in duplicate (1680 datapoints in total) and reported in an anonymous format. Samples were categorised into 7 different types: Edible, Extract, Infusion, Liquid, Other, Plant material, and Solid. Each category was divided into the following weight by percentage concentration levels: <0.1 wt.-%, 0.1 wt.-% to 1 wt.-% and finally >1 wt.-%. The results indicated that high amounts of tetrahydrocannabinol (THC) are present in most of the cannabis-based products in South Africa. This is of concern due to the health implications of these products, and the current South African legislation related to cannabidiol (CBD) and THC. For heavy metal residues a total of 310 samples were analysed. The submitted samples were divided into different category classifications and grouped according to relevance for oral or inhalation specification. The results showed an alarming 15% sample failure rate compared to the oral specification limit and a 44% failure rate compared to the inhalation specification limit. It is of the utmost importance for manufacturers to have the appropriate quality control regimes in place, especially for heavy metal residues, in South Africa. Furthermore, it is imperative to ensure regulation is enforced and the South African public is educated about the risks associated with using these products. Solvent residue analysis employed a total of 279 samples in duplicate and the results are reported in an anonymised format. The results showed an alarming 37% sample solvent residue failure rate with respect to adherence to USP 467 specification. As seen from the facets discussed above, manufacturers, as well as cultivators should adhere to the current GMP guidelines set forth, to ensure the safety of the consumer as well as the quality of the product produced. With the current findings the safety of consumers is brought into question. With this data South African regulators as well as the public might be informed about the current state of cannabis-based products.