Foot volume increase on nifedipine is not prevented by pretreatment with diuretics.

Objective: Despite their natriuretic effects, dihydropyridine calcium-channel blockers (CCBs) often induce ankle oedema, probably due to vasodilation in the dependent legs. Since concomitant administration of frusemide does not prevent the acute increase in foot volume on nifedipine, we investigated whether diuretic pretreatment attenuates foot swelling on CCBs.

Methods: In four separate experiments, 10 healthy volunteers received: (i) 20 mg of nifedipine without active pretreatment (pretreatment with placebo only); (ii) 20 mg of nifedipine after 5 days' treatment with amiloride 5 mg twice daily; (iii) 20 mg of nifedipine after 5 days' treatment with chlorthalidone 50 mg once daily; and (iv) no active drugs (pretreatment with placebo and placebo in place of nifedipine) as the control.