Dược Động Học :
▧ Absorption :
Significant absorption within 1 hour and peak plasma levels are reached in 2 to 4 hours. Onset of action occurs within one hour.
▧ Volume of Distribution :
Steady state Vd=0.125 L/kg; Vd during elimination phase=0.155 L/kg.
▧ Protein binding :
Unchanged drug is ~99% bound to serum proteins; 4-trans-hydroxyglyburide is greater than 97% bound to serum proteins. Protein binding is primarily nonionic making glyburide and is less likely to displace or be displaced by drugs that bind via an ionic mechanism.
▧ Metabolism :
Primarily hepatic (mainly cytochrome P450 3A4). The major metabolite is the 4-trans-hydroxy derivative. A second metabolite, the 3-cis-hydroxy derivative, also occurs. These metabolites do not contribute clinically significant hypoglycemic action in humans as they are only weakly active; however, retention of 4-trans-hydroxyglyburide may prolong the hypoglycemic effect of the agent in those with severe renal impairment.
▧ Route of Elimination :
Glyburide is excreted as metabolites in the bile and urine, approximately 50% by each route.
This dual excretory pathway is qualitatively different from that of other sulfonylureas, which are excreted primarily in the urine.
▧ Half Life :
1.4-1.8 hours (unchanged drug only); 10 hours (metabolites included). Duration of effect is 12-24 hours.
▧ Clearance :
78 ml/hr/kg in healthy adults. Clearance may be substantially decreased in those with severe renal impairment.