Pharmacology of VTE Flashcards
Vitamin K
Group of fat soluble essential factors for modification of protein for blood coag
Vitamin K1
Phylloquinone/Phytonadione
Vitamin K2
Menaquinone
Role of Vitamin K
Required to add carboxyl groups on Factors II, VII, IX< X and protein C/S
Factors II, VII, XI, X need
to be carboxylated to become Ca binding active froms
Enzyme for activation of factors is?
Gamma-glutamyl carboxylase
Vitamin K defieciency
Increased tendency to bleed
Induction of fetal bone abnormalities via osteocalcin not getting activated
Vitamin K Antagonists
Warfarin/Coumadin
Block VKOR which takes the oxygenated form of Vitamin K back to regular Vitamin K
Which form of warfarin enantiomers is most potent?
S
Warfarin has no direct effect on
Previously circulating clotting factors
Warfarin A & PK
Oral
Hepatic + CYP (esp 2C9)
Teratogenic
Warfarin dosing
Based on continual clinical and laboratory monitoring (INR)
Prothrombin Time
Extrinsic pathway
Monitor warfarin dose
Vitamin K depedent clotting factor sensitivity varies though
INR
Correction for differences in teh sensitivity of thromboplastin reagents
Allows for comparison of results between labs and standardizes reporting of the prothrombin time!!!!!
ISI
The higher the ISIS, the less sensitive the thromboplastin
Warfarin AE
Bleeding (Vit K = antidote or immediate effect = frozen plasma) Osteoporosis Purple toe syndrome Warfarin-induced skin necrosis Teratogenic (X)
Purple Toe Syndrome
Small deposits of cholesterol breaking loose and flowing into the blood vessels in the skin of the feet
Conditions that reduce warfarin activity?
Cholestyramine (bile acid sequestrant) Nephrotic syndrome: reduced half life Barbiturates, Rifampin, Phenytoin, alcohol (P450) Vitamin K Pregnancy
Conditions that increase warfarin activity?
Antimicrobials (reduce vitamin K)
Vit K Deficiency
Impaired hepatic function
Age
