Over 100 controlled clinical trials supported therapeutic potential of cannabinoids | Research

The takeaway

More than 100 controlled clinical trials since 1975 led to the approval of dronabinol, nabilone, and a cannabis extract in several countries, with the most common side effects being tiredness and dizziness.

Read this if you want a concise overview of the clinical evidence supporting medical cannabinoids.

Over 100 controlled clinical trials since 1975

What the researchers found

This review cataloged the therapeutic evidence for cannabinoids, noting that over 100 controlled clinical trials had been conducted since 1975. These trials led to three approved cannabis-based medicines: dronabinol, nabilone, and a 1:1 THC:CBD extract (Sativex).

In Germany, the cannabis extract was approved in 2011 for moderate-to-severe MS spasticity. It was commonly used off-label for anorexia, nausea, and neuropathic pain. Patients could also apply for government permission to buy medicinal cannabis flowers for supervised self-treatment.

The most common side effects (tiredness and dizziness) affected more than 10% of patients, but tolerance to these effects nearly always developed within a short time. Withdrawal symptoms were "hardly ever a problem in the therapeutic setting."

Why it matters

By counting over 100 controlled trials, this review countered the claim that cannabis lacked scientific evidence. The regulatory framework in Germany, including patient access to medicinal flowers, represented one of the most developed systems at the time.

The numbers in context

Over 100 controlled clinical trials since 1975. Three approved medicines: dronabinol, nabilone, THC:CBD extract. Side effects >10%: tiredness, dizziness. Tolerance to side effects developed quickly. Withdrawal rarely problematic in clinical use.

How the study worked

Selective literature review of controlled clinical trials and regulatory approvals for cannabis-based medicines. Published in a German medical journal with a European regulatory perspective.

What this study cannot tell us

Selective rather than systematic review. German/European focus. "Over 100 trials" includes trials of varying quality and for different conditions. Some conditions had much more evidence than others.

How to read the evidence

Selective review summarizing a large body of controlled trial evidence. Strong evidence base overall, though the review itself is selective rather than systematic.

When this study was published

Published in 2012. Germany has since become one of Europe's largest medical cannabis markets with expanded indications.

The bigger picture

The European regulatory approach to medical cannabis, particularly Germany's, differed from the US. This review reflected a system where cannabis-based medicines moved through traditional pharmaceutical approval while also allowing supervised flower access.

Questions still open

Is the German model of combined pharmaceutical approval and flower access optimal? Which of the 100+ trials are most clinically relevant? Should more conditions be approved for cannabinoid treatment?

Common questions

How much scientific evidence supports medical cannabis?

As of this review, over 100 controlled clinical trials had been conducted since 1975, leading to three approved cannabis-based medicines. The strongest evidence was for MS spasticity, nausea, and neuropathic pain.

Do the side effects go away?

The most common side effects (tiredness and dizziness) affected more than 10% of patients initially, but tolerance to these effects nearly always developed within a short time. Withdrawal symptoms were rarely a problem when used as prescribed.

Read the original research

The therapeutic potential of cannabis and cannabinoids.

Deutsches Arzteblatt international, 109(29-30), 495-501

View on PubMed ↗

Citation

Grotenhermen, Franjo; Müller-Vahl, Kirsten. (2012). The therapeutic potential of cannabis and cannabinoids.. Deutsches Arzteblatt international, 109(29-30), 495-501.