Investigation of Potential Pharmacodynamic and Pharmacokinetic Interactions Between Selexipag and Warfarin in Healthy Male Subjects

Abstract

Purpose: Selexipag is a new orally available nonprostanoid prostacyclin receptor agonist for the treatment of pulmonary arterial hypertension. Warfarin is commonly used in patients with pulmonary arterial hypertension. Possible pharmacodynamic and pharmacokinetic interactions between selexipag and warfarin in healthy individuals were investigated.

Methods: This was a double-blind, 2-way, 2-treatment crossover, Phase I study. Nineteen healthy men received a single dose of selexipag 400 μg or placebo on day 1, followed by selexipag 400 μg or placebo BID on days 2 to 12. A concomitant single dose of warfarin 20 mg was administered in the morning of day 8.

Findings: Both treatments were well tolerated. The most frequently reported adverse event was headache in both treatments. Geometric mean ratios and 90% CIs of the maximum international normalized ratio (geometric mean ratio = 0.96; 90% CI, 0.90-1.03) and international normalized ratio AUC0-144h (geometric mean ratio = 0.98; 90% CI, 0.96-1.00)] during treatment with warfarin and selexipag versus treatment with only warfarin were inside the reference limits of 0.80 to 1.25. The 90% CIs of the geometric mean ratios of AUC and Cmax for R- and S-warfarin during treatment with warfarin and selexipag versus treatment with warfarin alone were inside the reference range of 0.80 to 1.25. After repeated-dose administration of 400 μg selexipag, the AUC of selexipag and its active metabolite, ACT-333679, at steady state were not affected by a single dose of 20 mg warfarin.

Implications: Steady-state levels of selexipag and ACT-333679 after repeated doses of 400 μg selexipag had no influence on the warfarin pharmacodynamic variables. There was no pharmacokinetic interaction between selexipag and warfarin.

Keywords: drug-drug interaction; pharmacodynamics; pharmacokinetics; selexipag; warfarin.