REPRODUCIBILITY OF ANGIOTENSIN-CONVERTING ENZYME-INHIBITOR INDUCED COUGH - A DOUBLE-BLIND RANDOMIZED STUDY

1 The reproducibility of angiotensin converting enzyme inhibitor induc ed cough was examined in a double-blind cross over study in patients p reviously shown to have exhibited this side effect. 2 Ninety-seven pat ients who had experienced angiotensin converting enzyme inhibitor coug h within the last 2 years were challenged with enalapril 20 mg daily f or 4 weeks to establish eligibility. Eighty-eight of 97 (91%) patients experienced a repeat of their cough symptoms. Sixty-four patients ent ered the double-blind part of the study where they were treated with e nalapril 20 mg and a renin inhibitor for up to 4 weeks in random order . These periods were separated by a minimum 4 week placebo wash out. 3 Of 59 evaluable patients who received enalapril a second time, 37 (62 .7%) experienced cough again. Of 62 patients on the renin inhibitor 16 (25.8%) experienced cough, however as it was not equi-efficacious to enalapril no valid comparison could be made. 4 Angiotensin converting enzyme inhibitor cough is not reproducible within patients, as other f actors are involved in the aetiology. Objective testing with blinded a ssessment together with symptom reporting, would give a more accurate measure of the incidence, and mechanism of this side effect.