Interaction between nifedipine and cardioactive drugs.
Nifedipine (N) and dehydronifedipine (DHN) plasma levels were measured by gas chromatography in 37 patients before and 2 h after the intake of 20 mg N. They suffered from cardiovascular diseases and were treated with N in daily doses of 30 or 60 mg in combination with nitrates, beta-receptor blocking agents, digitoxin, saluretics and/or vasodilators for several weeks or months. Simultaneously, blood pressure and heart rate were measured. For comparison, six healthy volunteers between the ages of 25 and 46 years took 20 mg N on an empty stomach. Their mean plasma N level amounted to 47.7 (SD: 13.6) ng.ml-1, the DHN level reached a mean value of 46.7 (SD: 22.8) ng.ml-1 2 h after administration. The mean plasma N level of the patients rose from 14.1 to 34.1 ng.ml-1 and that of DHN, from 5.4 to 16.0 ng.ml-1. In 26 of 37 patients the heart rate increased without correlating with the altitude of the N level. The ratio DHN/N was 0.83 (SD 0.24) in the volunteers, while in the patients it amounted to 0.59 (SD 0.30). If the criterion DHN/N plasma level reached values greater than 1.0 the N degradation was enhanced (n = 4), and if it reached values less than 0.2, N degradation was depressed (n = 9). The results did not indicate inhibition of N degradation under long-term treatment with simultaneously administered cardioactive drugs.
Haustein
K O
KO
Institute of Clinical Pharmacology, Medical Academy Erfurt, Germany.
Assmann
I
I
Hüller
G
G
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects*; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009543:Nifedipine / Q000008:administration & dosage / Q000097:blood*
D009543:Nifedipine