Final: Warfarin Flashcards
Warfarin exhibits an ______ model.
Irreversible.
Warfarin PK:
1. Warfarin exhibits _____ bioavailability.
2. The Tmax for warfarin is _____, with a Vd of _____.
3. Warfarin is _______ protein bound.
4. The _____ isomer of warfarin has higher Cl.
- good (90%)
- 1-2 hours, 0.08-0.12 L/kg
- Highly (99%)
- S-isomer.
Which phase of warfarin disposition has a steep curve? What dosage sees this primarily?
Distribution—> Low doses.
Warfarin pK is initially _____ on day 1, but become _____ by day 7.
Nonlinear
Linear
Warfarin is a _____ extraction ratio drug.
Low Extraction Ratio
______ is metabolized by CYP2C9, while _____ is metabolized by many enzymes.
S-isomer of Warfarin
R-Isomer of Warfarin.
What is the mechanism of warfarin?
Inhibits the interconversion of Vitamin K, slowing the production of the following clotting factors.
—> II, VII, IX, X
—> Protein C and S
What Pharmacodynamic Response Model does Warfarin Follow?
The Indirect Pharmacodynamic Response Model—> Meaning there i s a delayed effect and the maximum response after a dose is not observed for at least 2 days.
T or F: Traditional TDM methods for warfarin monitoring are more than effective for managing warfarin patients.
F: These have limited value.
What is the INR goal for patients on warfarin?
2-3
What are some factors influencing warfarin PK?
- Age (decreased CL)
- Genetic Polymorphisms (CYP2C9 and CKORC1)
- Body Weight (obese = decreased initial response)
- Sex
- Drug Interactions
- Disease States
- Adherence
- Vitamin K intake
What genetic polymorphisms may influence the PKPD of warfarin?
- CYP2C9 and VKORC1
What is the new focus of managed warfarin patients?
Population PK/PD coupled with feedback measurements using Bayesian methods to improve individualization of warfarin.
