Medical cannabis in SA: Weighing the evidence

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Current limited evidence of the benefits of medical cannabis may be outweighed by the lack of consistent efficacy and risk of adverse effects, since no products are currently registered by the SA Health Products Regulatory Authority (SAHPRA), concludes a study in the SA Medical Journal. They note that currently there is only low-level or no convincing evidence for medical cannabis use for chronic pain, sleep and weight disorders, and neuropsychiatric disorders. 

There is high-quality evidence for the use of medical cannabis in some childhood epilepsy and it could be considered in chemically-induced nausea and vomiting and multiple sclerosis-associated spasticity.  

Researchers in the faculties of medicine and health sciences and Stellenbosch University and the University of Cape Town, the Centre for Medical Ethics and Law at Stellenbosch University, Red Cross War Memorial Children’s Hospital and the Neurosciences Institute at the University of Cape Town, write in the SA Medical Journal that the South African Constitutional Court recently decriminalised the private cultivation, possession and use of cannabis by adults.

They write: 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 South Africa , 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.

The study concludes:

High-quality evidence for medical cannabis is still in its infancy. Regulatory overview of the use of medical cannabis is essential to ensure the availability of safe, effective and good-quality products. Overall, the current limited benefits of medical cannabis for most indications may be outweighed by the lack of consistent efficacy and risk of adverse effects, including multiple drug interactions with no data to guide management. Currently, for the majority of proposed medical cannabis indications, safer and generally more effective pharmacological therapies are regulatorily approved. However, good- quality data support the use of medical cannabis for rare forms of childhood epilepsy resistant to current registered antiseizure medications. This may justify facilitated access in SA to medical cannabis via section 21. Medical cannabis could also be considered for patients with intractable CINV and MS-associated spasticity. Unfortunately, the cost of medical cannabis may be prohibitive for these patient groups. The regulatory and legal landscape on the use of medical cannabis is evolving, and will guide prescription and recreational use in the coming years. Until such time, healthcare practitioners should be aware of their role in responsible prescription and provision of advice to patients. 

Key points 

• Few healthcare practitioners are adequately equipped with knowledge of the evidence, indications and legislation to support the safe use of medical cannabis. 

  • Grown cannabis contains varying amounts of THC and CBD, depending on various cultivation factors.
  • Unregulated and unregistered cannabis products may be of inadequate quality and unverified composition, and are not guaranteed to be safe or effective.
  • Convincing evidence exists for the use of registered medical cannabis for Dravet and Lennox-Gastaut syndromes. Moderate evidence exists for the management of CINV and MS-associated spasticity. Currently, low-level or no convincing evidence exists 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, including serious adverse effects.
  • The evolving regulatory and legal landscape on the use of medical cannabis will guide prescription and recreational use in the coming years.

Authors
R van Rensburg; V Pillay-Fuentes Lorente; M Blockman; K Moodley; JM Wilmshurst; EH Decloedt

SA Medical Journal material

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