Lack of effect of co-trimoxazole on the pharmacokinetics and pharmacodynamics of nifedipine.

The pharmacokinetics of nifedipine and its primary oxidised metabolite, M-I were studied in nine healthy volunteers following a single oral dose of 20 mg nifedipine alone or after pretreatment with oral co-trimoxazole. Following pretreatment with co-trimoxazole, no significant effect was detected on maximum plasma concentration, elimination half-life, or area under the plasma concentration-time curve of either nifedipine or M-I, nor on the blood pressure response to nifedipine.