Using Therapeutic Drug Monitoring and Pharmacovigilance to Overcome Some of the Challenges of Developing Medicinal Cannabis from Botanical Origins.

PURPOSE: Plants belonging to the genus Cannabis have been domesticated and used by humans for millennia. Thought to have originated from central Asia, cannabis has been harnessed for its nutritional, therapeutic, and psychoactive properties, and as a source of fiber (Office of Medicinal Cannabis. Analytical Monograph Cannabis Flos. Den Haag, The Netherlands: Office of Medicinal Cannabis; 2014). Human use of cannabis is not novel; however, its medicalization offers a new pharmacotherapeutic frontier. METHODS: The authors recently reported a systematic review of the contaminants of cannabis (National Academies of Sciences Engineering, and Medicine. The health effects of cannabis and cannabinoids: the current state of evidence and recommendations for research. Washington, DC; 2017). This article draws on the research limitations identified by that review and examines a collection of the relevant literature to provide an appreciation of the current evidence base. RESULTS: The review explores the current status of cannabis in medical use, the drug development aspects that apply when taking a plant through to pill development, and the roles that therapeutic drug monitoring and pharmacovigilance have to guide practice until the drug development information on medicinal cannabis preparations is complete. CONCLUSIONS: A surge of public and clinical interest in the possible therapeutic applications of constituent cannabinoids has potentiated global legislative and policy reform. However, our understanding of its properties, optimized use, and harmful effects remains incomplete (Therapeutic Goods Administration. Guidance for the use of medicinal cannabis in Australia In: Department of Health Department, editor. Woden ACT Australian Government 2017; Dryburgh LM, Bolan NS, Grof CP, Galettis P, Schneider J, Lucas CJ, et al. Cannabis contaminants: sources, distribution, human toxicity and pharmacologic effects. Brit J Clin Pharm. 2018;84(11):2468-2476). In particular, a comprehensive appreciation of its toxicity profile is lacking.

Cannabis contaminants: sources, distribution, human toxicity and pharmacologic effects.

There has been a resurgence in interest and use of the cannabis plant for medical purposes. However, an in-depth understanding of plant contaminants and toxin effects on stability of plant compounds and human bioavailability is needed. This systematic review aims to assess current understanding of the contaminants of cannabis and their effect on human health, leading to the identification of knowledge gaps for future investigation. A systematic search of seven indexed biological and biomedical databases and the Cochrane library was undertaken from inception up to December 2017. A qualitative synthesis of filtered results was undertaken after independent assessment for eligibility by two reviewers. The common cannabis contaminants include microbes, heavy metals and pesticides. Their direct human toxicity is poorly quantified but include infection, carcinogenicity, reproductive and developmental impacts. Cannabis dosing formulations and administration routes affect the transformation and bioavailability of contaminants. There may be important pharmacokinetic interactions between the alkaloid active ingredients of cannabis (i.e. phytocannabinoids) and contaminants but these are not yet identified nor quantified. There is significant paucity in the literature describing the prevalence and human impact of cannabis contaminants. Advances in the availability of cannabis globally warrant further research in this area, particularly when being used for patients.