As regulatory approval of medical marijuana spreads in the US, practicing clinicians need to be apprised of cannabis-related indications, efficacy, and adverse effects.
In an effort to develop viable standards for patient counseling and education, Jayesh Parmar, PhD, and colleagues from the school of pharmacy and health professions at the University of Maryland Eastern Shore in Princess Anne, Maryland, and colleagues reviewed 68 abstracts, summarizing common medical uses of cannabis-based medications and their safety in various disease states and populations. The study was published online September 16 in Research in Social and Administrative Pharmacy.
“The overall purpose of this article was to provide clinicians with evidence-based counseling guidelines that can be strengthened as new clinical information becomes available,” lead author Dr. Parmar told Clinical Pain Advisor. “This is a starting point on developing counseling guidelines for the clinicians, subject to their review and modification.”
The study found that all 3 FDA-approved products (dronabinol, nabilone, and nabiximols), as well as inhaled and ingested marijuana products, are often used to treat neuropathic pain.
Other common uses for dronabinol included weight gain and chemotherapy-induced nausea and vomiting (CINV); nabilone is also used for CINV, while nabiximols is favored for spasticity in multiple sclerosis (MS). Smoked marijuana is also commonly used to treat glaucoma, and orally ingested marijuana is often used to improve sleep and seizure control in MS.
According to Barth Wilsey, MD, from the department of physical medicine and rehabilitation at the University of California Davis Medical Center in Sacramento, California, the key findings mirror those of a recent rigorous review involving 79 randomized trials with almost 6,500 participants.2
“There was moderate-quality evidence to support the use of cannabinoids for the treatment of chronic pain and spasticity. There was low-quality evidence suggesting that cannabinoids were associated with improvements in nausea and vomiting due to chemotherapy, weight gain in HIV infection, sleep disorders, and Tourette syndrome,” Dr. Wilsey told Clinical Pain Advisor.
Moreover, cannabinoids were linked to an increased risk of short-term adverse events,” Dr. Wilsey pointed out. These were most commonly related to CNS, cardiovascular, and respiratory effects.
Although medical marijuana may be beneficial for selected medical conditions, further research is warranted, Dr. Parmar said, noting that he and his team are currently reviewing data and developing guidelines for marijuana use in CINV and pain relief.
A number of legal and regulatory issues also need to be addressed before marijuana use can be established in clinical practice. Federal laws still view marijuana as an illegal substance, although enforcement is low in states that have approved access to cannabis-ingested products, Dr. Parmar noted.
Benefits of Marijuana Treatment Agreement
It is important that clinical practitioners communicate with patients regarding the goals of marijuana therapy and associated potential risks and benefits. Patients should be made aware that in contrast with recreational use, medical marijuana is intended for delivery in low, cumulative, therapeutic doses.
According to Dr. Wilsey, a treatment agreement might be the best way to convey treatment goals and improve patient understanding and compliance.3,4 As with prescribed opioids, written agreements between prescriber and patient can help deter misuse and abuse by delineating patient responsibilities with respect to dosing, random drug screens, and appointments.
Dosing Strategies Remain Unclear
Optimal dosing strategies for cannabis-based medications and ingested marijuana remain unclear, highlighting the importance of clinical counseling guidelines.
Wide variation exists in the reported dose of delta-9-tetrahydrocannabinol (Δ 9-THC) needed to produce CNS effects, Dr. Wilsey said. Two recent studies suggest that lower doses of THC provide pain relief similar to that of higher doses, yet decrease the risk for adverse events.5,6
A patient-specific, self-titrating model has therefore been suggested as a useful dosing paradigm for medicinal cannabis, allowing patients to take the lowest effective dose of THC.
“The use of flexible dosing has been previously performed for the treatment of neuropathic pain with nabiximols where patients self-titrated their overall dose and pattern of dosing, according to their response to and tolerance of the medicine,” Dr. Wilsey pointed out, noting that the delayed-onset associated with dronabinol and nabilone may make titration difficult.
Efficacy may vary with formulation
According to Dr. Wilsey, some experts have suggested that whole plant cannabis or ingested marijuana is superior to the FDA-approved cannabis-based medications. The concept may explain why long-marketed oral cannabinoids are not widely used in the US.
“Peak plasma concentrations occur 1 to six hours after ingestion, with a magnitude approximately 10% of that achieved with smoking. It has been postulated that the preference expressed by patients for herbal cannabis is a result of the faster onset and shorter duration of action, allowing titration of dose to the desired effect,” Dr. Wilsey said.
Dr. Wilsey and colleagues plan to compare the efficacy and safety of herbal cannabis and oral Δ 9-THC (dronabinol) directly in a clinical population.
“We plan on performing a randomized, controlled 8-week trial comparing the effectiveness of these two cannabinoid preparations in patients with neuropathic low back pain. In addition to studying efficacy and side effect profiles, we will also perform a driving simulation study to determine the real-world impact of these two cannabinoid treatments,” Dr. Wilsey concluded.
1. Parmar JR, Forrest, Benjamin D, Freeman, Robert A. Medical marijuana patient counseling points for health care professionals based on trends in the medical uses, efficacy, and adverse effects of cannabis-based pharmaceutical drugs.Research in Social and Administrative Pharmacy. 2015. Published online September 16, 2015. doi:10.1016/j.sapharm.2015.09.002
2. Whiting PF, et al. Cannabinoids for medical use: A systematic review and meta-analysis. JAMA. 2015; 313 (24).
3. Ware MA, Ziemianski D. Medical education on cannabis and cannabinoids: Perspectives, challenges, and opportunities. Clin Pharmacol Ther. 2015; 97(6): 548-550.
4. Wilsey B, et al. The medicinal cannabis treatment agreement: Providing information to chronic pain patients via a written document. Clin J Pain. 2014.
5. Wilsey, B, et al. A randomized, placebo-controlled, crossover trial of cannabis cigarettes in neuropathic pain.The Journal of Pain. 2008; 9(6): 506-521.
6. Wilsey, B, et al. Low dose vaporized cannabis significantly improves neuropathic pain. The Journal of Pain. 2013; 14(2): 136-148
Article written by Beth Gilbert. She has an undergraduate degree in chemical engineering from Lehigh University and a Master’s in biomedical engineering from Columbia University.