Effect of indomethacin on the pharmacokinetics and pharmacodynamics of felodipine.

1. We studied the effects of pre-treatment with oral indomethacin (25 mg four times daily for 3 days) on the pharmacokinetics, haemodynamics and diuretic properties of oral felodipine (10 mg single dose) in 12 healthy male volunteers using a placebo controlled double-blind four-way crossover protocol. 2. Felodipine with or without indomethacin pretreatment reduced standing diastolic blood pressure (P less than 0.001) at 0.5 to 3.0 h after dosing compared with placebo or indomethacin alone. Systolic blood pressures during indomethacin treatment alone were consistently higher than the other three treatment groups (P less than 0.01), presumably due to sodium and fluid retention. 3. Felodipine and felodipine plus indomethacin produced significantly greater excretion of urine and urinary sodium, but not of urinary potassium or creatinine when compared with placebo (P less than 0.01) over an 8 h period. 4. The pharmacokinetic parameters of felodipine (Cmax, tmax, t1/2 and AUC), the concentration-response curves for blood pressure lowering effects, the reflex tachycardia, diuretic properties and side-effects profile of felodipine were not significantly altered by indomethacin pretreatment in normal volunteers.