Coronary arterial lesions induced by endothelin antagonists

Area of Science:

• Pharmacology
• Cardiovascular Science
• Toxicology

Background:

• Endothelins (ETs) are potent vasoconstrictors and pressor peptides involved in cardiac, renal, and endocrine functions.
• Elevated ET-1 levels in conditions like heart failure and hypertension suggest the endothelin system as a therapeutic target.
• Selective endothelin receptor antagonists are being developed for various cardiovascular and renal diseases.

Purpose of the Study:

• To evaluate the effects of a non-peptidic, selective endothelin ET(A) receptor antagonist in preclinical species.
• To assess the potential for cardiac vascular lesions associated with endothelin receptor antagonism.
• To identify species-specific responses to endothelin receptor antagonists.

Main Methods:

• Administration of a selective ET(A) receptor antagonist via continuous intravenous infusion.
• Study conducted in beagle dogs, rats, and Goettingen minipigs.
• Histopathological examination of cardiac vasculature and other tissues.

Main Results:

• Mild arteriopathy, characterized by medial degeneration, was observed in coronary arteries of the dog's heart (atrium and ventricle).
• No cardiac vascular lesions were noted in rats or minipigs, despite higher plasma concentrations and exposure in these species.
• No adverse effects were observed in blood vessels of other organs or tissues in any species.

Conclusions:

• Dogs exhibit unique sensitivity to the development of cardiac vascular lesions induced by this endothelin receptor antagonist.
• Findings are consistent with other endothelin antagonists and vasodilating drugs, suggesting a class effect in sensitive species.
• The study underscores the importance of species selection in preclinical safety assessments for endothelin-targeting therapies.