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Angiotensin-converting enzyme and the cough reflex
A H Morice1, R Lowry, M J Brown
1Clinical Pharmacology Unit, Addenbrooke's Hospital, Cambridge.
Lancet (London, England)
|November 14, 1987
Summary
Coughing is a side effect of angiotensin-converting enzyme (ACE) inhibitors. This study found that captopril, an ACE inhibitor, altered the cough reflex response to capsaicin in healthy volunteers.
Area of Science:
- Pharmacology
- Respiratory Medicine
- Clinical Trials
Background:
- Angiotensin-converting enzyme (ACE) inhibitors are commonly prescribed medications.
- Cough is a recognized side effect associated with ACE inhibitor use.
- The precise mechanism underlying ACE inhibitor-induced cough remains unclear.
Purpose of the Study:
- To investigate the effect of ACE inhibition on the human cough reflex.
- To determine if captopril alters sensitivity to various cough-inducing stimuli.
Main Methods:
- A double-blind, randomized study involving sixteen healthy volunteers.
- Participants received either captopril (25 mg) or a placebo orally.
- Cough reflex sensitivity was assessed using nebulized distilled water, citric acid, and incremental capsaicin doses.
Main Results:
- Captopril did not significantly alter responses to distilled water or citric acid challenges.
- Captopril significantly shifted the dose-response curve for capsaicin-induced cough.
- The geometric mean dose of capsaicin eliciting 20 coughs/min was lower with captopril (1.3 mumol/l) versus placebo (2.8 mumol/l) (p=0.04).
Conclusions:
- ACE inhibition with captopril modifies the cough reflex sensitivity to capsaicin in normal subjects.
- This suggests a role for ACE in the cough reflex pathway.
- ACE may metabolize substrates other than angiotensin I, influencing cough.