High inter-individual variability of vardenafil pharmacokinetics in patients with pulmonary hypertension

Abstract

To evaluate the pharmacokinetic parameters of a single oral dose of vardenafil in patients with pulmonary hypertension (PH). Sixteen patients with PH received vardenafil in single oral doses (20, 10 or 5 mg), and repeated blood sampling for up to 9 h was performed. Vardenafil plasma concentration was determined using liquid chromatography tandem mass spectrometry. Pharmacokinetic parameters were calculated using model-independent analysis. The plasma vardenafil concentration increased rapidly and exhibited a median time to maximum plasma concentration (t(max)) of 1 h and a mean elimination half-life (t(1/2)) of 3.4 h. The geometric mean and standard deviation of (1) the peak plasma concentration (C(max)) was 21.4 ± 1.7 μg/L, (2) the normalized C(max) (C(max, norm)) 79.1 ± 1.6 g/L, (3) the area under the time-concentration curve (AUC) 71.5 ± 1.6 μg · h/L and (4) the normalized AUC (AUC(norm)) 261.6 ± 1.7 g · h/L. Patients co-medicated with bosentan reached t(max) later and had a 90% reduction of C(max), C(max, norm), AUC and AUC(norm). The pharmacokinetic profile of vardenafil overall revealed considerable inter-individual variability in patients with PH. Co-medication with bosentan resulted in a pharmacokinetic drug interaction, leading to significantly decreased plasma concentrations of vardenafil. Therapeutic drug monitoring for individual dose optimization may be warranted.