Selective inhibitory effects of nifedipine and verapamil on oxidative metabolism: effects on theophylline.
Nine healthy male volunteers were studied to assess the possibility of an interaction between theophylline and nifedipine or verapamil using a randomised, crossover design. Subjects received theophylline 125 mg 8 hourly with and without nifedipine 20 mg 12 hourly and verapamil 80 mg 8 hourly. Nifedipine treatment reduced mean total theophylline clearance by 9%, due to decreased clearances via 1- and 3-demethylation. Verapamil treatment reduced mean total theophylline clearance by 14%, due to decreased clearances via 1- and 3-demethylation and 8-hydroxylation. Verapamil and nifedipine at usual clinical doses are unlikely to cause clinically significant changes in theophylline disposition.
Robson
R A
RA
Department of Clinical Pharmacology, Flinders Medical Centre, Bedford Park, South Australia.
Miners
J O
JO
Birkett
D J
DJ
D000293:Adolescent; D000328:Adult; D006801:Humans; D008297:Male; D009543:Nifedipine / Q000494:pharmacology*; D010084:Oxidation-Reduction; D013806:Theophylline / Q000378:metabolism*; D014700:Verapamil / Q000494:pharmacology*
D013806:Theophylline; D014700:Verapamil; D009543:Nifedipine