sitaxsentan + ritonavir

Sitaxsentan + ritonavir is a combination of two small molecule drugs. **Sitaxsentan** is an endothelin receptor antagonist, primarily selective for the endothelin-A receptor, used for treatment of pulmonary arterial hypertension (PAH) before being discontinued due to safety concerns, notably hepatotoxicity. It acts by competitively blocking the binding of endothelin-1 to endothelin-A and endothelin-B receptors, with higher affinity for the former, thereby reducing pulmonary vascular resistance and improving hemodynamics in PAH[4][5]. **Ritonavir** is a potent inhibitor of HIV-1 protease, originally developed as an antiretroviral but now widely used as a pharmacokinetic booster for other drugs metabolized via the CYP3A4/5 pathway due to its strong CYP3A inhibition[1]. Coadministration of these drugs is of pharmacological interest primarily due to drug-drug interaction considerations: sitaxsentan is metabolized by CYP2C9 and CYP3A4/5 and is a moderate inhibitor of several CYP enzymes, while ritonavir is a strong CYP3A4 inhibitor and substrate, making the combination clinically significant for interaction potential rather than for direct synergistic therapeutic action[2][3].

Other names

sitaxsentan sodiumritonavirum