[Efficacy and safety of medicinal cannabis: results of the CaPRis study]

In the 1990s, the endocannabinoid system was discovered as part of the human physiology. Since then, the effects of cannabis as a medicine have been researched more systematically. To summarize the scientific knowledge, the German Federal Ministry of Health commissioned an expertise.The project "Cannabis: Potential and Risks: a Scientific Analysis" (CaPRis), which started in 2016, aimed at analyzing the potential of medicinal cannabis and the risks of recreational cannabis use. A search of systematic reviews (SRs) and randomized-controlled trials (RCTs) were conducted in five international databases (publication date: 2006-2017). For the medical use of cannabis 16 SRs (of 186 RCTs) were included from a global search and nine further RCTs were comprised from a de novo search. All studies were methodologically assessed.Evidence for the efficacy of cannabis medicine (given as an adjunct to other medication) was found in patients with chronic pain and spasticity due to multiple sclerosis. Benefits were also found for appetite stimulation, improvement of nausea, and weight gain in patients with cancer, HIV/AIDS or in palliative care. Effects were often small. For other physical or mental disorders, only few or no controlled human studies are available. Adverse effects of cannabis medicine are often reported; severe adverse effects were mentioned in single cases only.To provide reliable treatment recommendations for clinicians and patients, more large-sized RCTs with follow-up assessments, consistent outcome measures, and active comparisons are needed.