Medical marijuana and the developing role of the pharmacist.

PURPOSE The pharmacology, therapeutic uses, safety, drug-drug interactions, and drug-disease interactions of medical marijuana are reviewed, and the legal issues related to its use and the implications of medical marijuana for the pharmacist are presented. SUMMARY Marijuana contains more than 460 active chemicals and over 60 unique cannabinoids. The legal landscape surrounding marijuana is surprisingly complex and unsettled. In the United States, 11 states and several municipalities have legalized medical marijuana. Another state provides legislation that allows patients to claim a defense of medical necessity. Nevertheless, patients using medical marijuana may never interact with a pharmacist. Marijuana is a Schedule I controlled substance and its use is illegal under federal law. Marijuana has a number of purported therapeutic uses with a broad range of supporting evidence. There are five general indications for medical marijuana: (1) severe nausea and vomiting associated with cancer chemotherapy or other causes, (2) weight loss associated with debilitating illnesses, including HIV infection and cancer, (3) spasticity secondary to neurologic diseases, such as multiple sclerosis, (4) pain syndromes, and (5) other uses, such as for glaucoma. Marijuana is associated with adverse psychiatric, cardiovascular, respiratory, and immunologic events. Moreover, marijuana may interact with a number of prescription drugs and concomitant disease states. CONCLUSION Several states have legalized the use of marijuana for chronic and debilitating medication conditions. Pharmacists need to understand the complex legal framework surrounding this issue so that they can protect themselves and better serve their patients.