In the first study, Fiona Campbell and colleagues, from the UK, established whether cannabinoids are an effective and safe option in the treatment of acute or chronic pain. They reviewed 9 trials, involving over 200 patients.
In all trials, cannabinoids were given either as tablets or by intramuscular injection. The authors found no studies on smoked cannabis.
In 8 of the 9 trials, cannabinoids were found to be no more effective than codeine tablets in controlling acute and chronic pain.
Furthermore, side-effects associated with the cannabinoids were common, and sometimes severe.
|Cannabinoids are the active substances in cannabis.|
|British Medical Journal|
In acute postoperative pain, cannabinoids are unlikely to be useful. However, they may be effective in chronic non-cancer pain, say the authors.
Cannabis is clearly unlikely to usurp existing effective treatments for postoperative pain, they conclude.
In the second study, a team from Switzerland investigated the effectiveness and safety of cannabis in preventing sickness induced by chemotherapy.
They analyzed 30 trials, involving over 1,300 patients. Three different cannabinoids were given, either as tablets or by intramuscular injection.
Across all trials, cannabinoids were found to be more effective than conventional anti-sickness drugs. However, no difference was found for patients receiving very low or very high levels of chemotherapy.
Most patients also preferred cannabinoids for future chemotherapy cycles.
Patients reported more side-effects with cannabinoids than with conventional drugs. Although some were potentially beneficial (euphoria, "high", sedation. or drowsiness), others were harmful (dizziness, depression, hallucinations).
These results offer arguments both for and against the use of cannabinoids in chemotherapy patients, say the authors.
They suggest that, in selected patients, cannabinoids may be useful as mood-enhancing aids for controlling chemotherapy-related sickness.