Article by Jacqueline Havelka
When medical cannabis laws made their debut in the latter half of the 1990s, they were intended to protect cancer patients from prosecution. These patients found a medication that combatted the harsh, nauseating side effects of chemotherapy, and though cannabis’ efficacy was largely anecdotal at the time, we can now look at the science of cannabinoids to better understand why it works to suppress nausea and vomiting.
What Is CINV and How Is It Treated?
Overpowering. That’s how cancer patients describe the onslaught that occurs within the first 24 hours after starting chemotherapy. Certainly patients fear the hair loss, but the most dreaded side effect is the extreme bouts of nausea and vomiting (called emesis). This isn’t just regular nausea–chemotherapy-induced nausea and vomiting (CINV) is severe and usually occurs right away, with a peak window of 6-24+ hours after treatment.
Traditional pharmaceuticals are used as anti-nausea (anti-emetic) therapies to prevent or minimize CINV. Dexamethasone, a corticosteroid prescribed for inflammatory conditions, is most commonly prescribed; as it turns out, it is also very effective in treating CINV. Serotonin receptor agonists called 5-HT3 (ondansetron, palonosetron, and aprepitant) have been effective when used with dexamethasone. Even antihistamines, antidepressants and anticonvulsants have been tried.
But what happens if these drugs don’t alleviate symptoms? Many chemotherapy patients don’t respond to traditional drugs and report that they can leave them feeling more drugged, more lethargic, and even delusional.
Cannabinoids have shown success in treating the symptoms of CINV. Two medicines, nabilone and dronabinol, are orally-administered synthetic cannabinoids (not to be confused with synthetic cannabis like K2 and Spice). The two are slightly different variations of delta-9-tetrahydrocannibinol (Δ9-THC), which naturally occurs in a cannabis plant. Dronabinol is marketed as Marinol from the US-based Banner Pharmacaps, and nabilone is sold as Cesamet by the Canadian company Valeant Pharmaceuticals International. Both are available in oral and inhaled solutions, and both have been approved for treatment of CINV.
Doctors will usually prescribe traditional medications first, but then try Marinol or Cesamet for patients who don’t respond to other pharmaceuticals.
Research on Synthetic Cannabinoids for Nausea Relief
In 1985, dronabinol and nabilone were both approved by the FDA for treatment of CINV. Since then, nearly 30 clinical trials have been conducted and show that synthetic cannabinoids are superior to traditional dopamine receptor antagonist medications for CINV.
Specifically, several clinical trials (1975-1996) involved 1,366 patients. Sixteen trials studied nabilone, and thirteen trials studied dronabinol. Placebos were used, and metoclopramide was used as a control. Cannabinoids alleviated CINV more effectively than either metoclopromide or placebos in all trials.