The interaction between indomethacin and captopril or enalapril in healthy volunteers

In this study eight healthy volunteers were involved in a randomized, cross-over trial in which they were treated with either 25 mg of captopril b.i.d. or 20 mg of enalapril o.i.d. alone or in combination with 50 mg of indomethacin b.i.d. in order to detect a difference between both converting enzyme inhibitors when interacting with indomethacin. Before and after each 4-d treatment period, blood pressure (determined by random zero sphygmomanometer), body weight, plasma renin activity, angiotensin converting enzyme, plasma potassium, serum creatinine and the 24-h urinary excretion of 6-keto-prostaglandin F1 alpha were measured. Indomethacin attenuated the decrease of supine diastolic blood pressure during treatment with captopril, but not with enalapril. However, the initial decrease of blood pressure on captopril was greater than on enalapril. Both converting enzyme inhibitors had no effect on the urinary excretion of 6-keto-prostaglandin F1 alpha, while indomethacin reduced it. The results suggest a difference between captopril and enalapril in interaction with indomethacin.