title: Effect of tolterodine on the anticoagulant actions and pharmacokinetics of single-dose warfarin in healthy volunteers.
abstract: This randomized, double-blind, crossover study investigated the potential effects of tolterodine ((R)-N,N-diisopropyl-3-(2-hydroxy-5-methyl-phenyl)-3-phenylpropanamine, CAS 124937-51-5), an antimuscarinic agent for the treatment of the overactive bladder, on the anticoagulant actions and pharmacokinetics of single-dose warfarin (CAS 81-81-2) in 20 healthy male volunteers. In terms of study design, volunteers randomly received oral tolterodine L-tartrate (2 mg twice daily) or matching placebo for 7 days, with a single oral dose of warfarin (25 mg) administered on day 4 of each treatment period. R-(+)- and S-(-)-warfarin pharmacokinetics were estimated from plasma levels measured up to 96 h post-dose, in conjunction with assessment of prothrombin time and factor VII activity. Pharmacokinetics of tolterodine and its active 5-hydroxymethyl metabolite ((R)-N,N-diisopropyl-3-(2-hydroxy-5-hydroxymethyl-phenyl)-3-phenylpropanamine; 5-HM), in the presence and absence of warfarin, were also determined. Relative to placebo, tolterodine had no discernible effect on the anticoagulant actions of warfarin. Point estimates of the tolterodine: placebo ratios for prothrombin time and factor VII activity were 1.00 (90% confidence interval [CI]: 0.91-1.10) and 0.91 (90% CI: 0.83-0.99), respectively, consistent with equivalence. No clinically significant changes in the pharmacokinetics of R-(+)- and S-(-)-warfarin were noted. Serum concentration-time profiles and the pharmacokinetics of tolterodine and 5-HM were similar in the presence and absence of warfarin. There were no safety concerns. These findings indicate that co-administration of tolterodine and warfarin is safe and well tolerated, with no clinically significant pharmacodynamic or kinetic interaction in healthy volunteers.
authors.affiliation: Department of Clinical Pharmacology, Pharmacia Corporation, Kalamazoo, Michigan, USA.
authors.forename: Mohamad
authors.initials: M
authors.lastname: Rahimy
authors.forename: Bengt
authors.initials: B
authors.lastname: Hallén
authors.forename: Prem
authors.initials: P
authors.lastname: Narang
mesh_terms: D000328:Adult; D000925:Anticoagulants / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000494:pharmacology; D019540:Area Under Curve; D001559:Benzhydryl Compounds / Q000009:adverse effects / Q000494:pharmacology*; D001711:Biotransformation; D001780:Blood Coagulation Tests; D003408:Cresols / Q000009:adverse effects / Q000494:pharmacology*; D004311:Double-Blind Method; D004347:Drug Interactions; D006801:Humans; D008297:Male; D018727:Muscarinic Antagonists / Q000009:adverse effects / Q000494:pharmacology*; D010665:Phenylpropanolamine; D013237:Stereoisomerism; D000068737:Tolterodine Tartrate; D014859:Warfarin / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000494:pharmacology
chemical_list: D000925:Anticoagulants; D001559:Benzhydryl Compounds; D003408:Cresols; D018727:Muscarinic Antagonists; D010665:Phenylpropanolamine; D014859:Warfarin; D000068737:Tolterodine Tartrate