A randomized, crossover comparison of warfarin products in the treatment of chronic atrial fibrillation.
OBJECTIVE
To compare the dosing requirements and international normalized ratios (INRs) associated with two bioequivalent crystalline warfarin sodium products in patients with chronic atrial fibrillation.


METHODS
A multicenter, single-blind (prescriber), randomized, crossover evaluation of Apothecon warfarin and DuPont warfarin (Coumadin) was conducted in consenting adults with chronic or paroxysmal atrial fibrillation who had been receiving DuPont warfarin chronically for the prevention of thromboembolism. Patients were randomly assigned to initially either continue DuPont warfarin or receive Apothecon warfarin for four weeks, with weekly evaluation of dosage and INR changes, safety, and efficacy. Subsequently, patients crossed over and received the other product for four weeks.


RESULTS
There were 113 patients randomized to receive study treatment. Neither the propensity for a dosage change or an INR change nor the magnitude of a dosage change or INR change appeared related to a particular warfarin product (NS for each variable after each study period). After four weeks of treatment, the same number of patients (n = 7) experienced a > or = 20% change in warfarin dosage from the respective baseline with each product. The number of patients with INRs outside the desired protocol range after four weeks of treatment was similar for both groups (< 1.8, n = 9 for both products, or > 3.2, n = 9 for DuPont, n = 10 for Apothecon). No major hemorrhagic or thromboemoblic events occurred.


CONCLUSIONS
The results of this study show that Apothecon warfarin and DuPont warfarin provide equivalent anticoagulation in patients with chronic or paroxysmal atrial fibrillation.
Weibert
R T
RT
Department of Clinical Pharmacy, School of Pharmacy, University of California, San Francisco, USA.
Yeager
B F
BF
Wittkowsky
A K
AK
Bussey
H I
HI
Wilson
D B
DB
Godwin
J E
JE
Adler
D S
DS
Black
E A
EA
McGee
D L
DL
Vlasses
P H
PH
D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy*; D002908:Chronic Disease; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D016896:Treatment Outcome; D014859:Warfarin / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*
D000925:Anticoagulants; D014859:Warfarin