Cannabinoids are no better than codeine for treating pain, and have far more serious side effects, according to a new review of published research.
A separate study surveyed the use of cannabinoids to combat nausea following chemotherapy. While the tablets or injections were slightly more effective than standard treatments, their side effects, plus the recent development of new, more powerful drugs, makes them a poor choice for nausea relief, say researchers in the UK and the Hopitaux Universitaires in Geneva, Switzerland.
However, large scale trials of cannabinoids to relieve some conditions for which good treatments do not exist are urgently needed, says Martin Tram猫r of the Hopitaux Universitaires.
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鈥淔or treating nausea after chemotherapy or post-operative pain, we do not really need better drugs. The ones we have are effective and have a reasonable level of side effects,鈥� Tram猫r told 快猫短视频.
鈥淏ut for some conditions, such as MS-related spasticity, we are desperate to find other drugs. It would be more useful to look at cannabinoid treatments for these conditions,鈥� he says.
Tram猫r鈥檚 team trawled medical databases and analysed 30 randomised controlled trials published between 1975 and 1997.
鈥淚f cannabinoids had reasonable efficacy and no side effects, I would say, why not use them? But what struck us was that there were side effects that were toxic in some of the patients,鈥� he says. A significant number of patients reported depression, hallucinations or paranoia, he adds.
Since most of the reviewed studies were conducted, new, highly effective serotonin-based drugs to combat nausea have been developed. This makes cannabinoids even less attractive options for treatment, Tram猫r says.
Fiona Campbell of the Pain Management Centre at the Queen鈥檚 Medical Centre in Nottingham, UK, and her team looked at research on using cannabinoids to treat pain. They analysed nine trials involving 222 patients. Five studies involved cancer patients, two concerned chronic pain not associated with cancer, and two focused on post-operative pain.
鈥淐annabinoids were no more effective than codeine in controlling acute and chronic pain and they had undesirable effects in depressing the central nervous system,鈥� comments Eija Kalso of Helsinki University Hospital in an editorial in the British Medical Journal.
He adds that most of the trials analysed by Campbell鈥檚 team dated back to the 1970s. Since then, improved pain-relieving drugs have been developed.
Kalso writes: 鈥淭he currently available cannabinoids clearly lose the battle in both efficacy and safety with the competitors of today.鈥� However, she adds: 鈥淔urther research may provide us with better cannabinoid compounds with potential new applications.鈥�
But he agrees with Tram猫r that current cannabinoids may have a place in combating hard-to-treat conditions such as MS and pain caused by nerve degeneration. A large scale trial investigating cannabis鈥檚 effect on MS symptoms is currently being conducted in the UK.
Journal reference: British Medical Journal (vol 323, p 2, 13, 16)