Medical marijuana and patient counseling

January 15, 2011

Under the federal Controlled Substances Act, marijuana is classified as Schedule I, a definition that gives it a high potential for abuse, with no current safe or medical use. Meanwhile, in 14 states, patients have access to medical marijuana upon physican recommendation.

Key Points

Under the federal Controlled Substances Act, marijuana is classified as Schedule I, a definition that gives it a high potential for abuse, with no current safe or medical use.

Meanwhile, in the state of California, as in 13 other states, patients have legal access to medical marijuana upon physician recommendation for the following approved indications: AIDS (anorexia), arthritis, cachexia, cancer, chronic pain, glaucoma, migraine headaches, muscle spasms, seizures, severe nausea, or any disabling, persistent medical symptom that if not alleviated would cause harm to the patient's safety or health.

Marinol is the only FDA-approved synthetic cannabinoid (CB1) used for chemotherapy-induced nausea and vomiting; it is argued that Marinol does not produce effects similar to those produced when its natural counterpart is smoked.

When medical marijuana enters the picture, within the pharmacy practice a simple consult becomes a legally and medically complex argument with no clear answer.

A simple Google search produces vast amounts of information based on anecdotal and recreational sources that can be misleading to the public. A search of databases such as PubMed, IOM, and NIMH led me to believe that the research data were mostly related to toxicology and mental health. Most of the information I found was not the randomized and blinded data upon which we base our pharmaceutical recommendations. However, as I researched this topic further, I did find the following general information, which may be helpful to our practice of pharmacy.

Possible drug-drug interactions: Opioids, antipsychotics, anesthetics, alcohol, benzodiazepines, muscle relaxants, protease inhibitors, theophylline, SSRIs, sildenafil, tricyclic antidepressants, anticholinergics, alpha-agonists, naltrexone, disulfiram, and lithium.

Cardiovascular adverse effects: Studies showed tachycardia, hypertension, orthostatic hypotension, and syncope. Case reports indicate a possible association between cannabis use and atrial fibrillation, especially in young individuals with no predisposing factors.

Respiratory adverse effects: Cannabis smoke is known to contain several potent carcinogens. It is inhaled deeply and held within the lungs, resulting in a longer exposure of carcinogens to lung tissue. As a consequence, there is a possible association between long-term use and lung-tissue inflammation, infections, bronchitis, and possibly cancer.

Carcinogenic adverse effects: Cannabis use by males under the age of 18 was recently associated with an elevated risk of testicular cancer. It is thought that hormonal surges associated with puberty place these younger men at higher risk, with the disease arising when primitive germ cells fail to develop properly and become vulnerable to malignancy. THC receptors have been found in the human brain, testes, heart, uterus, spleen, and certain immune-system cells.

Marijuana use for medical or recreational purposes, especially in California, is not going away. States are challenging the legal status of medical marijuana as it progresses toward the status of tobacco and alcohol as a public health issue.

In my opinion, the Schedule I classification of cannabis by the federal government limits the scientific study of potential risks and possible benefits of the drug. More information is necessary to develop the cautionary strategies employed in connection with other medications and with environmental hazards such as use of tobacco. If physicians are "medically" recommending marijuana use, I believe the information should be available to pharmacists that will enable us to answer our patients' questions properly, just as we would answer their questions about other medications.

I hope I'm better prepared for my next consult.

Leslie Bohner is a fourth-year pharmacy student at Touro University in Vallejo, Calif. She has a degree in Spanish/Bilingual Education from University of California, Irvine, and works for Kaiser Permanente in southern California. She can be reached at