Influence of the H2-receptor antagonists cimetidine and ranitidine on the pharmacokinetics of nimodipine in healthy volunteers.

A possible interaction between the calcium antagonist nimodipine and the H2-receptor antagonists cimetidine and ranitidine has been investigated in two separate studies in healthy subjects. In eight young volunteers the concomitant administration of nimodipine 30 mg t.i.d. and cimetidine 1000 mg/d for 7 days led to a significant increase of the relative bioavailability of nimodipine. The changes in the pharmacokinetic parameters were not accompanied by discernible haemodynamic effects or any change in the tolerability of nimodipine. There was no evidence of any significant change in the steady-state pharmacokinetics of nimodipine during five days of combined treatment with 30 mg t.i.d. nimodipine and ranitidine 300 mg/d given as single morning dose to twelve healthy, elderly subjects. Analysis of haemodynamics, clinical chemistry and tolerance also did not reveal any difference between the two treatment periods.