Verapamil-induced inhibition of theophylline elimination in healthy humans.
The interaction between theophylline and verapamil was investigated in 7 healthy volunteers. Oral administration of verapamil in a dose of 120 mg t.i.d. for 7 days caused a significant inhibition of the elimination of theophylline (5 mg/kg intravenously). Theophylline clearance was reduced from 45.2 to 36.1 ml/hr/kg (20.1%; P less than 0.005). The apparent steady-state volume of distribution of the drug was not influenced. The terminal half-life of theophylline was increased from 6.80 to 8.23 hr (21.0%; P less than 0.001). Increased steady-state plasma theophylline concentrations may thus be expected when verapamil is added to a drug regimen which includes theophylline.
Nielsen-Kudsk
J E
JE
Department of Internal Medicine, Silkeborg General Hospital.
Buhl
J S
JS
Johannessen
A C
AC
D000328:Adult; D004347:Drug Interactions; D005260:Female; D006207:Half-Life; D006801:Humans; D008297:Male; D013806:Theophylline / Q000097:blood / Q000493:pharmacokinetics*; D014700:Verapamil / Q000494:pharmacology*
D013806:Theophylline; D014700:Verapamil