Prevalence of desloratadine poor metabolizer phenotype in healthy Jordanian males

Purpose To study the prevalence of desloratadine slow metabolizer phenotype among a group of healthy Jordanian male volunteers. Methods A total of 62 healthy Jordanian male volunteers were included in this study. A single 5 mg desloratadine oral tablet was given and blood samples were taken to determine the desloratadine and 3‐hydroxydesloratadine (3‐OH‐desloratadine) concentrations using a specific liquid chromatography‐mass spectrometric method (LC/MS/MS). The determination of pharmacokinetic parameters of all the individuals was determined by using Kinetica® program version 4.1. Poor metabolizers or slow metabolizers of desloratadine were determined as individuals having a 3‐OH‐desloratadine to desloratadine exposure ratio lower than 10% or a desloratadine half‐life ≥ 50 h. Results Among the 62 volunteers who participated in the study there were only two volunteers who were labeled as desloratadine slow metabolizers, giving a prevalence of 3.2%. The maximum plasma concentrations ( C max ) were similar in the extensive and slow metabolizers groups but a longer time ( t max ) was needed to achieve this concentration in one of the volunteers who was a desloratadine slow metabolizer. Conclusion The incidence of the poor metabolizer phenotype of desloratadine in the Jordanian population studied is similar to certain ethnic groups (e.g. Asian, Caucasians and Hispanic); however, it is lower than other populations (e.g. American Indians and Black). Copyright © 2012 John Wiley & Sons, Ltd.