Nielsen-Kudsk JE, Buhl JS, Johannessen AC. Verapamil-induced inhibition of theophylline elimination in healthy humans.
PHARMACOLOGY & TOXICOLOGY 1990;
66:101-3. [PMID:
2315261 DOI:
10.1111/j.1600-0773.1990.tb00713.x]
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Abstract
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.
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