Dose-dependence of the nifedipine-digoxin interaction?
The dose-dependence of the nifedipine-digoxin interaction was investigated in seven healthy subjects. After an adequate loading dose of digoxin for 2 weeks, 0.25 mg digoxin b.i.d. was given by mouth by itself. Afterwards, 0.25 mg digoxin was given twice a day for three 1-week periods in combination with capsules of nifedipine, 5, 10, or 20 mg, respectively, given on a thrice-daily basis. The study ended with a digoxin monotherapy phase lasting 7 days. All three doses of nifedipine significantly increased digoxin plasma concentrations and AUC compared with digoxin monotherapy. Thus, for example, the AUC was 10.16 +/- 0.88 ng/ml . hr (mean +/- SE) when digoxin was given alone and 12.33 +/- 1.59 ng/ml . hr with concurrent nifedipine, 5 mg t.i.d. (P less than 0.05). Nifedipine causes a slight but significant increase (15%) in digoxin plasma concentrations and AUC. This effect did not depend on the nifedipine dose given in the range studied.
D000284:Administration, Oral; D000328:Adult; D003404:Creatinine / Q000378:metabolism; D004077:Digoxin / Q000097:blood / Q000378:metabolism*; D004347:Drug Interactions; D006321:Heart / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D008297:Male; D009543:Nifedipine / Q000494:pharmacology*
D004077:Digoxin; D003404:Creatinine; D009543:Nifedipine