Does enalapril produce dry cough?
Yes. Enalapril is an angiotensin converting enzyme (ACE) inhibitor that can produce dry cough in the patients on long term use. Ofcourse this adverse effect is not only found with enalapril but it is a class effect shown by all ACE inhibitors.
The dry cough is side effect of ACE inhibitors but not shown by angiotensin receptor blockers (ARBs) as later doesnot inhibit ACE enzyme.
ACE inhibitors act by inhibition of synthesis of angiotensin II (AT II) from angiotensin I (AT I) by inhibiting ACE enzyme.
AT II is required for vasoconstriction and stimulated by conditions like hypotension which activate renin-angiotensin-system (RAS) leading to synthesis of AT II. In this way, AT II restores the tone of the blood vessels and maintains the homeostasis.
But in few of the conditions like hypertension or heart failure, AT II is inappropriately activated leading to persistent raise in blood pressure. AT II also causes stimulation of aldosterone secretion resulting in sodium and water reabsorption.
Thus ACE inhibitors block actions of AT II leading to vasodilation and a fall in blood pressure.But inhibition of ACE is not only associated with positive effects but also with some unwanted effects. One of the clinically significant adverse effect is development of dry cough. This effect os related to inhibition of ACE enzyme.
ACE is not only responsible for conversion of AT I to AT II but also stimulates the degradation of bradykinin into inactive peptides.
So when ACE is blocked, the inactivation of bradykinin is suppressed raising its levels. Bradykinin is a vasodilator as well as airway irritant. It is accumulated in upper bronchial tract and stimulates unmyelinated C-fibers resulting in cough reflux.