NEW YORK, Oct 06 (Reuters Health) -- The Food and Drug Administration (FDA) has recently granted approval to Dr. Ethan Russo, of Missoula, Montana, to begin a study of the medicinal effects of marijuana in patients with migraine. However, the study has one last hurdle -- it must also be approved by the National Institute on Drug Abuse (NIDA), which will supply the marijuana for the study.
The internal Public Health Service review required by the NIDA "applies to cannabis and no other substances," Russo told Reuters Health.
Prior to instituting this review process last May, the NIDA required researchers to get approval and funding from the National Institutes of Health before initiating any study of medicinal marijuana.
As approved by the FDA, Russo's study will enroll 40 patients with severe migraine and compare the effects of smoked marijuana and oral dronabinol (a synthetic version of THC, the principle psychoactive component of marijuana), with injections of sumatriptan, an approved drug for migraines.
Patients will be randomly assigned to one of two groups for 3 months then crossed-over to the other part of the study, Russo said in an interview. Patients in one group will receive either sumatriptan or marijuana plus oral ("dummy") placebo at the onset of headache and patients in the other group will receive either sumatriptan or THC-devoid marijuana plus dronabinol.
Russo hopes to start the study this year. If he does not receive approval to use NIDA-supplied marijuana for the study, Russo may attempt to obtain the drug from a foreign source, British-based GW Pharmaceuticals. However, this would require "another whole process" to gain permission to import marijuana, he said.
But even if the study does gain the approval of NIDA, there are other issues to consider, Russo told Reuters Health. The marijuana supplied by NIDA is generally three to four times less potent than "true medical grade marijuana," which can have important implications for both efficacy and safety.
"Like with any drug, if the potency isn't there, the clinical response may be suboptimal or may not be there at all," Russo said. Moreover, the lower the potency of the marijuana, the more times patients will need to inhale before they feel an effect, increasing the risk of respiratory side effects.
And still another issue stands in the way of the trial -- funding. According to regulations, the $250,000 study will need to be funded entirely through private grants. Although Russo and colleagues cannot begin to raise these funds until the approval process is complete, they have "identified a number of people who we hope will be interested in funding the research," Russo told Reuters Health.
