In vitro studies of the interaction between cetirizine and H2 receptor antagonists using spectrophotometry and reversed-phase high-performance liquid chromatography

Abstract

Cetirizine, a second-generation H1 receptor antagonist, is used for the treatment of allergic disorders. For some of these diseases, combined H1 and H2 therapy generally is more effective than treatment exclusively with H1 or H2, although this synergistic effect has not been found in all studies. Moreover, extensive in vivo studies have investigated the effects that the coadministration of the H2 receptor antagonists have on the pharmacokinetics and pharmacodynamics of the H1 receptor antagonists. The current study therefore adopted an in vitro approach to investigate the interaction of cetirizine with commonly administered H2 receptor antagonists (i.e., cimetidine, ranitidine, and famotidine) in simulating body fluids at different pH levels and at 37°C using reversed-phase high-performance liquid chromatography (RP-HPLC) and ultraviolet (UV) spectrophotometry. An RP-HPLC method also was developed and validated for the simultaneous determination of these drugs. The mobile phase consisted of methanol:water (80:20) pumped at a flow rate of 1 mL/min. The chromatogram was monitored at 230 nm. The results from the UV spectrophotometry and RP-HPLC clearly indicated that the availability of cetirizine was unaffected by simultaneous administration of H1 and H2 receptor antagonists. Hence the two drugs can be safely administered with one another.