Captopril is a commonly used anti-hypertensive drug. the most common side effect observed with its prolonged use is the development of a dry cough sometimes accompanied by wheezing. The cause for the cough is likely to be:
a) increase in the plasma levels of bradykinin
b) idiosyncratic reaction to the drug
c) due to decrease in the blood pressure.
d) decrease in the angiotensin levels in the plasma
e) none of the above
Answer:
a) increase in the plasma levels of bradykinin
Explanation
Captopril is a commonly used anti hypertensive drug which belongs to the category of Angiotensin Converting Ezyme inhibitors (ACE inhibitors). The drug exerts its action by the inhibition of an enzyme Peptidyl Dipeptidase. Now this enzyme is responsible for the inactivation of bradykinin. the inhibtion of the enzyme Peptidyl Dipeptidase prevents the inactivation of bradykinin. this results in an increase in the plasma levels of bradykinin. Increased bradykinin irritates the tracheobronchial tree which results in the dry cough and sometimes wheezing.