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Comparison of the bioavailabilities and anticoagulant activities of two warfarin formulations
Author(s) -
Stirling Yvonne,
Howarth D. J.,
Stockley R.,
Bland R.,
Towler C. M.,
Harding S. M.
Publication year - 1982
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1982.tb07287.x
Subject(s) - warfarin , bioavailability , volunteer , warfarin sodium , anticoagulant , pharmacology , medicine , clotting factor , prothrombin time , prothrombin complex concentrate , factor vii , prothrombin complex , coagulation , atrial fibrillation , biology , agronomy
Changes in the British Pharmacopoeia dissolution time requirements have necessitated reformulation of warfarin sodium (‘Marevan’). The old and new formulations were compared with each other in eight healthy volunteers given a single 15 mg dose of each in a cross‐over study and also in 19 patients receiving warfarin therapy. In the volunteer study, a significant but small increase in bioavailability was observed for the new formulation. However, the effects of the two formulations on the prothrombin ratio and on clotting factors II, VII, IX and X were not significantly different. Irrespective of formulation, the greatest changes in factors II, VII and X were observed after the first dose of warfarin. With factor IX, the greatest response was observed after the second dose. The clinical study in patients confirmed that the old and new formulations of Marevan are interchangeable on a dose for dose basis. A sensitive semi‐automated warfarin assay technique is described.