Thursday 21 April 2016

ACE inhibitors- why they cause cough

#KYJ - #KnowingYourJargon
ACE inhibitors and that nasty Cough.

With many classes of blood pressure drugs on the market, it can be a mind storm navigating them all as nurses.

A common first line antihypertensive is the humble ACE inhibitor.  It's main side effect is cough and it drives patients and their partners crazy.
... But why? 
How does it cause cough?

Well let's understand ACE.
Angiotensin Converting Enzyme.

ACE is created in lungs and there, it has a role in destroying inflammatory chemicals called Bradykinin and Substance P.   These pro-inflammation proteins cause lung tissue irritation- notably cough (tussis).

ACE also notably converts Angiotensin into a vasoconstrictor that raises Blood Pressure.  It stands to reason if I inhibit ACE then I can't convert Angiotensin.
Hence its valuable role as a blood pressure lowering drug.

BUT....

If you give an ACE inhibitor, and prevent the breakdown of bradykinin and substance P (Inflammatory chemicals), there is an accumulation of these protussive mediators (coughing stimulants) in the respiratory tract. 

This side effect is not dose-dependent and often precludes the use of all agents within the drug class.

Common offenders are Lisinopril, Perindopril, and a new one released after March and before May called AprilπŸ˜†πŸ˜†πŸ˜†.

No seriously.  ACE inhibitors cause cough and often this means that the patient needs a new approach to BP control.

 

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