Inhibitory Effect of Citalopram on the Pharmacokinetics of Carvedilol in Rats and in vitro Models

Abstract

Background/Aims: The aim of this study was to investigate the drug-drug interaction between carvedilol and citalopram based on carvedilol metabolism in vitro and his pharmacokinetics (PKs) in vivo after the oral administration of the single drug and both drugs, and reveal citalopram effects on the PKs of carvedilol. Methods: Each rat was cannulated on the femoral vein, prior to being connected to BASi Culex ABC®. Carvedilol was orally administrated in rats (3.57 mg/kg body weight [b.w.]) in the absence of citalopram or after a pre-treatment with multiple oral doses of citalopram (1.42 mg/kg b.w.). Plasma concentrations of carvedilol were determined using high-performance liquid chromatography-MS at the designated time points after drug administration, and the main PK parameters were calculated by noncompartmental analysis. In addition, effects of citalopram on the metabolic rate of carvedilol were investigated using rat-pooled liver microsome incubation systems. Results: During co-administration, significant increases of the area under the plasma concentration-time curve as well as of the peak plasma concentration were observed. The rat-pooled liver microsome incubation experiment indicated that citalopram could decrease the metabolic rate of carvedilol. Conclusion: Citalopram co-administration led to a significant alteration of carvedilol's PK profile in rats; it also demonstrated, in vitro, these effects could be explained by the existence of a drug-drug interaction mediated by CYP2D6 inhibition.