[The effects of verapamil and nifedipine on the biotransformation of model substances and on the indocyanine green elimination].

Abstract

Twelve healthy subjects received a cocktail of model substances (containing metamizol: 1000 mg, caffeine: 200 mg, sulfadimidine: 500 mg, and debrisoquine: 10 mg) alone and on the fifth day of a five day therapy of oral verapamil (3 x 80 mg) or nifedipine (3 x 20 mg) to assess the effect of verapamil and nifedipine on hepatic biotransformation. To investigate liver blood flow intravenous indocyanine green (0,5 mg/kg) was given 12 and 1 hours after oral verapamil (80 mg) or nifedipine (20 mg). In the presented study an influence of verapamil and nifedipine treatment on the hepatic drug oxidizing system was not observed. The elimination half-life of intravenous indocyanine green was only 1 hour after oral nifedipine (20 mg) significantly decreased. 12 hours after nifedipine (20 mg) or verapamil (80 mg) as well as 1 hour after verapamil (80 mg) treatment no change in indocyanine green elimination was observed. The estimated increase of liver blood flow after oral nifedipine may cause increased absorption of other oral administered drugs and may accelerate hepatic elimination of drug with high hepatic extraction rate. 6 fast an 6 slow acetylators were found. This classification did not change after nifedipine or verapamil therapy.