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Pharmacokinetic and pharmacodynamic interactions between diltiazem and quinidine
Author(s) -
Laganière Sylvie,
Davies Richard F.,
Carignan Germain,
Foris Kathy,
Goernert Lynne,
Carrier Karen,
Pereira Conrad,
McGilveray Iain
Publication year - 1996
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1016/s0009-9236(96)90052-1
Subject(s) - quinidine , diltiazem , pharmacokinetics , pharmacology , pharmacodynamics , crossover study , oral administration , drug interaction , medicine , placebo , calcium , alternative medicine , pathology
Objectives To examine the pharmacokinetic and pharmacodynamic interactions between quinidine and diltiazem because both drugs can inhibit drug metabolism. Methods Twelve fasting, healthy male volunteers (age, 24 ± 5 years; weight, 75 ± 10 kg) received a single oral dose of diltiazem (60 mg) or quinidine (200 mg), alone and on a background of the other drug, in a crossover study. Background treatment consisted of 100 mg quinidine twice a day or 90 mg sustained‐release diltiazem twice a day for 2 days before the study day. Results Pretreatment with diltiazem significantly ( p < 0.05) increased the area under the curve of quinidine from 7414 ± 1965 to 11,213 ± 2610 ng · hr/ml and increased its terminal elimination half‐life (t 1/2 ) from 6.8 ± 1.1 to 9.3 ± 1.5 hours. Its oral clearance was decreased from 0.39 ± 0.1 to 0.25 ± 0.1 L/hr/kg, whereas the maximal concentration was not significantly affected. Diltiazem disposition was not significantly affected by pretreatment with quinidine. Diltiazem pretreatment increased QT c and PR intervals and decreased heart rate and diastolic blood pressure. No significant pharmacodynamic differences were shown for diltiazem alone versus quinidine pretreatment. Conclusion Diltiazem significantly decreased the clearance and increased the t 1/22 of quinidine, but quinidine did not alter the kinetics of diltiazem with the dose used. No significant pharmacodynamic interaction was shown for the combination that would not be predicted from individual drug administration. Clinical Pharmacology & Therapeutics (1996) 60 , 255–264; doi: