Medical cannabis: What practitioners need to know

Abstract

The South African (SA) Constitutional Court recently decriminalised the private cultivation, possession and use of cannabis by adults. Cannabis contains varying amounts of the cannabinoids delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), depending on various cultivation factors. No commercial plant-derived cannabis products are currently registered by the SA Health Products Regulatory Authority (SAHPRA) for medical use. Such products are therefore unregulated, but are freely available in SA, and may be of inadequate quality and unverified composition, and not guaranteed to be safe or effective. SAHPRA has to date approved only one synthetic medical cannabis product, dronabinol. Evidence supporting benefit from medical cannabis exists for two drug-resistant childhood forms of epilepsy, Dravet syndrome and Lennox-Gastaut syndrome. Adjuvant therapy with medical cannabis can reduce seizure frequency for Lennox-Gastaut syndrome and Dravet syndrome by 18.8% and 22.8%, respectively, and may be beneficial for other rare forms of epilepsy. There is moderate evidence for chemotherapy-induced nausea and vomiting with the synthetic cannabinoids. Multiple sclerosis-associated spasticity showed a small clinical improvement in self-reported spasticity when a purified form of THC/CBD was added to existing therapy. Currently, low-level or no convincing evidence exists for the use of medical cannabis for chronic pain, sleep and weight disorders, and neuropsychiatric disorders. Cannabis is associated with a greater risk of adverse effects than active and placebo controls, and may be involved in clinically significant drug-drug interactions. The evolving regulatory and legal landscape on the use of medical cannabis will guide prescription and recreational use in the coming years.