The 5-HT3 antagonists, such as ondansetron, are regarded as the most effective drugs to treat cancer chemotherapy induced nausea and vomiting. The natural cannabinoids THC and CBD (cannabidiol) are also known to inhibit these symptoms. The relative and combined effectiveness of these drugs in suppressing vomiting produced by cisplatin was investigated in shrews. Cisplatin is a chemotherapeutic agent that causes severe emesis.

Researchers of the Wilfrid Laurier University in Waterloo, Canada, demonstrated that ondansetron and THC both dose- dependently suppressed cisplatin-induced vomiting and retching in shrews. Furthermore, a combined pre-treatment of doses of the two drugs that were ineffective alone completely suppressed vomiting and retching. CBD produced a biphasic effect, suppressing vomiting at low doses and increasing it at high doses.

In two earlier clinical studies by Artim and DiBella (1983) and Lane and colleagues (1991) THC increased the anti-emetic effect of prochlorperazine in humans who underwent chemotherapy. The new animal study shows that cannabinoids may help to suppress nausea and vomiting that are not controlled by 5-HT3 antagonists alone. (Source: Kwiatkowska M, Parker LA, Burton P, Mechoulam R. A comparative analysis of the potential of cannabinoids and ondansetron to suppress cisplatin-induced emesis in the Suncus murinus (house musk shrew). Psychopharmacology (Berl) 2004 Jan 22, [electronic publication ahead of print])