Clinical pharmacology of neurokinin-1 receptor antagonists for the treatment of nausea and vomiting associated with chemotherapy.

INTRODUCTION: Five NK-1 RA formulations are commercially available to treat the delayed phase of chemotherapy-induced nausea and vomiting (CINV) occurring between days 2-5 post chemotherapy (aprepitant oral capsule and suspension, fosaprepitant intravenous infusion, netupitant/palonosetron capsules and rolapitant tablet) but no direct comparative studies have been conducted to determine their relative clinical utility. Areas covered: Information on pharmacology and safety of the NK-1 RAs derived from PubMed showed that all bind the NK-1 receptor with high affinity and selectivity. There is substantial variation in the disposition and time course in the body of NK-1 RAs because of the differential effects of hepatic metabolism. Unlike netupitant and rolapitant, aprepitant is metabolized extensively by cytochrome P450 (CYP) 3A4. Aprepitant and netupitant also both inhibit CYP3A4. Consequently, aprepitant not only has a much shorter elimination half-life than netupitant and rolapitant but also a more prolific drug interaction profile. All of the NK-1 RAs are efficacious and safe, and are suitable for use in a range of different patient populations, including those with mild or moderate hepatic or renal impairment. Expert opinion: While discovery of NK-1 RAs represents a major breakthrough in CINV control, further work is needed to improve control of chemotherapy-induced nausea.