Chemotherapy-induced
nausea and
vomiting (CINV) remains a significant problem in the care of
cancer patients. Although the use of
serotonin (5-HT3) receptor antagonists, as well as neurokinin-1 inhibitors, has reduced rates of acute
emesis, many patients still experience acute
vomiting; moreover, these agents have reduced efficacy in preventing
nausea, delayed CINV, and breakthrough CINV.
Nausea, in particular, continues to have a major--and often overlooked--impact on patients' quality of life. Optimizing the treatment for CINV likely will involve combinations of agents that inhibit the numerous
neurotransmitter systems involved in
nausea and
vomiting reflexes.
Cannabinoids are active in many of these systems, and two oral formulations,
dronabinol (
Marinol) and
nabilone (
Cesamet), are approved by the US Food and Drug Administration for use in CINV refractory to conventional
antiemetic therapy. Agents in this class have shown superiority to
dopamine receptor antagonists in preventing CINV, and there is some evidence that the combination of a
dopamine antagonist and
cannabinoid is superior to either alone and is particularly effective in preventing
nausea. The presence of side effects from the
cannabinoids may have slowed their adoption into clinical practice, but in a number of comparative clinical trials, patients have expressed a clear preference for the
cannabinoid, choosing its efficacy over any undesired effects. Improvement in
antiemetic therapy across the entire spectrum of CINV will involve the use of agents with different mechanisms of action in concurrent or sequential combinations, and the best such combinations should be identified. In this effort, the utility of the
cannabinoids should not be overlooked.