Abstract
Dear Editor:
We read with interest the article by Casarett et al. 1 on the Internet anonymous report of perception of effectiveness of tetrahydrocannabinol (THC)/cannabidiol (CBD). The interest in the potential medical value of cannabis has grown over the past decade. Studies have focused on two main cannabinoids: THC and CBD. Reported medical uses for cannabinoids include treatment of nausea, anorexia, insomnia, pain, anxiety, and depression among others.2,3 However, in the literature, medical benefits of marijuana and cannabinoids have been found to be mixed at best. 4 In addition, there has been growing enthusiasm over CBD due to the proposed absence of psychotomimetic effects. Ideally, it would be optimal for patients to take medications with no risks of psychoactive toxicities.
The study by Casarett et al. discussed an interesting concept of determining an optimal ratio of THC and CBD in reducing symptom distress from the patient's perspective. Although the results are interesting, they may not accurately reflect palliative care patient characteristics and symptom distress. Data were extracted from a mobile app where medical cannabis users self-report cannabis use and symptom intensity. Owing to the data and privacy restrictions, it was not possible to differentiate patients who have advanced illness versus those who were relatively healthier. In addition, the mean age recorded was quite young compared with average age of palliative care patients. The symptoms recorded, while they reflect common palliative care symptoms, do not include significant symptoms such as nausea and nociceptive pain, specifically cancer pain. This may be reflective of the disease characteristics of nonpalliative care cannabis users using the app leaving the authors with a more limited group of symptoms to assess.
Patients suffering from advanced illnesses have multiple comorbidities that might considerably increase the likelihood of cannabis-related toxicity. In addition, they are frequently receiving multiple drugs with potential severe neurotoxic interactions, including opioids, neuroleptic agents, benzodiazepines, and certain antiemetic agents. There is a potential for interaction, not only at the pharmacodynamics level but also at the pharmacokinetic level with cytochrome P450 enzyme inhibition by CBD, with palliative care drugs as well as anticancer agents. 5
Knowledge regarding the potential uses, benefits, interactions, and toxicities regarding THC and CBD products are still quite limited with the dearth of available standardized clinical studies, particularly in palliative care patients. We recommend health care professionals to be diligent in assessing their patients' use of these products as patients may not readily report use. Health care professionals and patients must also recognize state and federal legislation regarding legalization and potential legal issues. More research is needed to safely apply these substances in regular clinical practice particularly in regard to dosing, efficacy, short- and long-term toxicities, and drug interactions.