Irreversible Antagonist

A drug that forms a covalent or extremely stable bond with a receptor, permanently inactivating it so that recovery of function requires synthesis of new receptor protein. Irreversible antagonists reduce the maximal response to agonists once spare receptors are exhausted, and their duration of action outlasts their plasma presence. They are valuable when sustained receptor blockade is desired.

أمثلة

• Phenoxybenzamine: irreversible alpha-adrenergic antagonist used in pheochromocytoma
• Aspirin: irreversible inhibitor of cyclooxygenase (COX-1 acetylation) in platelets
• Omeprazole: irreversible proton pump inhibitor via covalent disulfide bond with H+/K+-ATPase