Managing the Patient on Medical Marijuana

Moderate evidence suggests that using medical marijuana can benefit chemotherapy-induced nausea and vomiting (CINV), as well as anorexia, and educating patients about the appropriate use of medical marijuana can maximize outcomes, according to a review presented by Lisa M. Holle, PharmD, BCOP, FHOPA, Associate Clinical Professor at UConn School of Pharmacy, and Associate Professor at UConn School of Medicine, presented at the 2019 HOPA Annual Conference.

Tetrahydrocannabinol (THC) is the primary component of cannabis and acts as weak partial agonist on CB1 and CB2 receptors. The psychoactive component can affect pain, appetite, digestion, emotions, thought processes, and depending on dose and patient tolerance, it can result in adverse events. The use of THC is viable for a myriad of symptoms and conditions including pain, nausea, muscle spasms, appetite stimulation, anxiety, depression, and post-traumatic stress disorder (PTSD). Conversely, cannabidiol (CBD) is a negative allosteric modulator of CB1, and this non-intoxicating component has been shown to manage similar symptoms as THC with added benefits as an anticonvulsant, anti-psychotic, neuroprotectant, and anti-inflammatory.

The benefits of medical marijuana in treating CINV have been exhibited in several studies. One was randomized controlled trial (RCT) crossover involving 15 patients who had underwent a high-dose of methotrexate and subsequently taken THC as a therapy – both as an inhaler (smoked) and oral remedy. Those patients saw a 93% reduction in nausea and vomiting (N/V).

Moreover, a previous randomized, double-blind, parallel group trial comprised of 469 patients with advanced cancer weight loss showed that the use of two synthetic cannabinoids (Dronabinol and Megestrol) increased appetite (by 66%) and weight gain (by 8%) when used in conjunction while also improving quality of life (QOL) and toxicity levels.

Despite these benefits, medical marijuana can have adverse effects – the most common being drowsiness, dry mouth, anxiety, and cough – however, serious side effects such as depression and psychosis, have occurred, although they are rare.

It is incumbent upon physicians to educate their patients about all facets of medical marijuana, from potential risks, such as drug interactions, to dosage recommendations. “General approach to cannabis initiation is start low, go slow, and stay low,” the researcher wrote in the presentation. “For cannabis inhalation, patients should start with one inhalation and wait 15 min. Then, they may increase by one inhalation every 15-30 min until desired symptom control has been achieved.”

Dr. Holle concluded by writing that documenting medical marijuana use, outcomes, and education within the electronic medical record “is important to optimize patient outcomes and safety.”