October 1, 2003
By Karla Gale
The synthetic cannabinoid CT-3 can significantly reduce neuropathic pain, according to the results of a randomized, placebo-controlled trial published in the October 1st issue of the Journal of the American Medical Association.
In preclinical trials, CT-3 was found to possess anti-inflammatory, analgesic, anti-allodynic, and even anti-tumor properties, lead author Dr. Matthias Karst told Reuters Health. However, the agent does not exert the psychoactive effects associated with tetrahydrocannabinol.
To further study this agent, Dr. Karst, of Hannover Medical School, Germany, and his team examined the analgesic efficacy and safety in a crossover trial with 21 patients with chronic neuropathic pain of at least 6 months' duration.
Patients underwent two 7-day treatments, one with CT-3 and one with placebo, with a 7-day washout period between. CT-3 was administered at 20 mg twice a day for 4 days, and then 40 mg twice a day for 3 days. Patients were permitted to continue taking their current pain-relieving medications, which included antipyretic and opioid analgesics, anticonvulsants and antidepressants.
Compared with placebo treatment, CT-3 led to significant improvements in pain according to a 100-mm visual analog scale at 3 hours after the initial dose. There was also a strong tendency for improvements on a verbal rating scale. Improvements in pain levels were less marked at 8 hours after dosing with CT-3. No dose-response relationship in pain relief or adverse events was noted after doubling the dose.
The primary adverse events reported more often for CT-3 than placebo were tiredness and dry mouth. Some also reported poor concentration, dizziness, sweating, and more pain. There were no major adverse events, and clinical and laboratory findings were comparable between treatment periods.
After the study was over, "about 30% of the participants asked to continue taking CT-3 or the alternative dronabinol to reduce their symptoms," Dr. Karst remarked in an interview with Reuters Health.
He noted that CT-3 has the potential to reduce patients' need for, and thus the adverse affects associated with, other antineuropathic medications. He predicts that CT-3 may also benefit patients with diabetic neuropathic pain. "And since the anti-inflammatory effects of CT-3 are very potent, I suggest that CT-3 will become a valuable tool for the treatment of rheumatic diseases like rheumatic arthritis," he added.
Copyright © 2003, Reuters Ltd.