No relation between angiotensin-converting enzyme (ACE) inhibitor-induced cough and ACE gene polymorphism, plasma bradykinin, substance P and ACE inhibitor concentration in Japanese patients

Persistent dry cough is well known as the most common side-effect of angiot ensin-converting enzyme (ACE) inhibitors. We examined the relationship betw een a cough and ACE gene polymorphism, plasma bradykinin (BK), substance P (SP) and ACE inhibitor concentrations in patients with hypertension or chro nic nephritis. First, ACE genotyping was carried out in 96 patients, 42 wit h coughs and 54 without coughs, which had been treated with various kinds o f ACE inhibitors. However, no significant difference in the ACE genotypes w as observed between the two groups. Second, the plasma concentrations of BK , SP and ACE inhibitor were measured in 12 patients, which were treated wit h trandolapril at a daily dose of 1 mg for 4-33 weeks. In 3 patients, the c ough was induced during the trandolapril therapy, while it was induced not in 9 patients. The plasma levels of BK and SP did not significantly change after trandolapril administration in the patients with and without coughs. Between the two groups, there were no significant differences in the plasma levels of BK and SP either before or after the trandolapril therapy. Also the plasma concentrations of trandolapril and trandolaprilat, the active me tabolite of trandolapril, did not significantly differ between the two grou ps. These results suggest that there is no significant relationship between the ACE inhibitor-induced cough and ACE gene polymorphism, plasma BK, SP a nd ACE inhibitor concentrations in patients with hypertension or chronic ne phritis.