Influence of severe renal dysfunction on the pharmacokinetics and metabolism of bosentan, a dual endothelin receptor antagonist.

BACKGROUND

One of the potential indications of bosentan, a dual endothelin receptor antagonist, is chronic heart failure. Patients with chronic heart failure frequently also suffer from impaired renal function.

OBJECTIVE

To explore the influence of severe renal dysfunction on the pharmacokinetics and metabolism of bosentan in a monocenter, open label, parallel group study.

METHODS

Eight renal patients with creatinine clearance 17 - 27 ml/min and 8 healthy subjects (creatinine clearance 99 - 135 ml/min) received a single oral dose of 125 mg bosentan and plasma samples drawn for up to 36 hours after administration were analyzed for bosentan and 3 metabolites.

RESULTS

The pharmacokinetic parameters of bosentan did not differ significantly between the study groups: geometric means (95% confidence interval) for Cmax were 1.8 (1.2 - 2.8) and 1.1 microg/ml (0.74 - 1.7), and for AUC0-infinity 7.2 (5.1 - 10.4) and 6.4 (3.4 - 11.2) microg x h/ml in healthy subjects and renal patients, respectively. Levels of the 3 CYP2C9- and CYP3A4-derived metabolites increased approximately 2-fold in renal patients, both in absolute terms and in relation to the parent compound. In renal patients, the exposure to Ro 48-5033, the only pharmacologically active metabolite, was 13% of that to bosentan.

CONCLUSION

Severe renal dysfunction did not affect the pharmacokinetics of bosentan to a clinically relevant extent and, therefore, no dose adjustments are deemed necessary in patients with any grade of renal insufficiency.