The
anticoagulant drug warfarin is a vitamin K antagonist (VKA), coumarin
derivative, formed by the racemic mixture of two optically active isomers known
by Rectus (R) and Sinister (S) enantiomers in equal proportion, being the
S-warfarin five times more potent. It is normally administered as the racemate
and its effect is observed normally within two to seven days after initiation
of therapy, according to the administered dose. Warfarin acts by interfering in
the interconversion of cyclic 2,3 vitamin K epoxide.
The vitamin K epoxide
reductase is inhibited by therapeutic doses of warfarin inhibiting thus the
synthesis of vitamin K-dependent factors, leading to inhibition of
γ-carboxylation of clotting factors II, VII, IV and X, and the anticoagulant proteins
C and S. Effects on prothrombin time are produced in 24 to 36 hours after the
initial dose and reach the maximum plasmatic concentration in 36 to 48 hours,
maintained for 48 hours or more after discontinuance of dosing. Read more>>>>>>>>>>>>>
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