Cannabis-Based Drug Relieves Arthritis Pain
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An oral spray containing marijuana extracts has offered pain relief to rheumatoid arthritis (RA) patients, according to British researchers. The patients did not have the typical highs achieved by smoking marijuana.
Called Sativex, the agent was tested in a five-week randomized, placebo-controlled trial that the investigators said was the first formal study using cannabis-based medications to treat rheumatoid arthritis.
“Anecdotally, of course, people have been using it for centuries,” said Candy McCabe, Ph.D., of the Royal National Hospital for Rheumatic Diseases here. “We’ve known in our clinic that patients are using street-based cannabis.”
The drug, made by GW Pharmaceuticals, of Salisbury, England, is a blend of whole plant extracts and contains two key ingredients in approximately equal amounts—delta-tetrahydrocannabinol (THC) and cannabidiol—that have been shown in animals to have beneficial effects for RA. Minor cannabinoids, including cannabinol, cannabichromene, and cannabigerol were also present in trace quantities.
Not approved in Britain or the U.S., the drug was licensed earlier this year in Canada for use in neuropathic pain associated with multiple sclerosis. The product is also being tested for cancer pain.
In the RA study, Dr. McCabe and colleagues reported online in the journal Rheumatology, 58 patients with active disease, not adequately controlled by standard medication, were randomized to Sativex or placebo.
Patients began with one use of the oral spray half an hour before bedtime and increased the number of uses—to a maximum of six a day—depending on response. Each use of the Sativex spray delivered 2.7 mg of THC and 2.5 mg of cannabidiol. Dosing was restricted to the evening hours.
The main efficacy measure was morning pain on movement on a one-to-10 scale. Secondary outcomes were morning pain at rest, morning stiffness, sleep quality, the Short-Form McGill Pain Questionnaire (SF-MPQ) and the 28-joint disease activity score (DAS 28).
The study found:
- For those in the treatment group, morning pain on movement was reduced significantly compared with placebo, as was pain at rest. The results were significant at p=0.044 and p=0.018, respectively.
- There was no significant difference in morning stiffness.
- Quality of sleep was significantly improved for those getting Sativex, at p=0.027.
- The DAS 28 scores for the treatment group were also significantly improved, at p=0.002.
- On the McGill pain questionnaire, patients getting the drug rated their pain as significantly less intense than did the placebo patients, at p=0.016.
- On two other aspects of the McGill questionnaire, there was no significant difference.
The authors described the effects on pain as “small and variable across the population; but they represent benefits of clinical relevance.” However, the beneficial effects occurred with a regimen restricted to evening dosing and may have been larger with 24-hour usage.
“Most important, the quality of sleep was improved, which we know in patients makes a big difference in how they perceive their pain the next day,” Dr. McCabe said. “It’s a very fatiguing disease.”
She said the improved sleep did not appear to arise because the patients were intoxicated by the drug. “They were getting the effect without feeling high,” she said.
Ronald Jubb, M.D., a rheumatologist, at the University Hospital Birmingham NHS Foundation Trust and a co-author of the study, said abuse of the medication appears to be “a very rare event.”
“The motivation of medicinal users of cannabis-based medicine is entirely different from recreational users,” Dr. Jubb said. “The former simply want symptom relief and the ability to go about their normal lives, and for them intoxication would be a distinct disadvantage; for the latter, smoking marijuana is infinitely more intoxicating than Sativex.”
Dr. McCabe said the study, while showing good efficacy, was mainly intended as a tolerance study, to establish the types and severity of adverse events and the risk of intoxication.
The researchers found that adverse events were mild or moderate, including mild dizziness, and there were no treatment-related withdrawals or serious adverse events in the active group.
Also, there was no indication of intoxication. “The patients’ perception was that this was a drug that was going to get them high, but we didn’t find that,” Dr. McCabe said.
The next step, she said, is to do a larger study in the same patient population. “This pilot study has given us sufficient data and good results to warrant a further, larger study,” she said.
Source: Rheumatology
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