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Pronunciation

WAR-fa-rin

Classifications

Therapeutic Classification: anticoagulants

Pharmacologic Classification: coumarins

Indications

BEERS REMS, High Alert


Action

  • Interferes with hepatic synthesis of vitamin K-dependent clotting factors (II, VII, IX, and X).
Therapeutic effects:
  • Prevention of thromboembolic events.

Pharmacokinetics

Absorption: Well absorbed from the GI tract after oral administration.

Distribution: Minimally distributed to tissues.

Protein Binding: 99%.

Metabolism/Excretion: Primarily metabolized by the liver via the CYP2C9 isoenzyme, with some metabolism via the CYP3A4 isoenzyme; the CYP2C9 isoenzyme exhibits genetic polymorphism (intermediate or poor metabolizers may have significantly (S)-warfarin concentrations and an risk of adverse reactions).

Half-Life: 42 hr.

Time/Action Profile

(effects on coagulation tests)

ROUTEONSETPEAKDURATION
PO36–72 hr5–7 days2–5 days



At a constant dose

After discontinuation



Contraind./Precautions

Contraindicated in:

Use Cautiously in:

Adv. Reactions/Side Effects

Derm: dermal necrosis

GI: cramps, nausea

GU: CALCIPHYLAXIS

Hemat: BLEEDING

Misc: fever

Interactions

Drug-drug:

Drug-Natural Products:

Route/Dosage

Availability

(Generic available)

Assessment

Lab Test Considerations:

Toxicity and Overdose:

Implementation

Patient/Family Teaching

Evaluation/Desired Outcomes

US Brand Names

Coumadin, Jantoven

Pill Image

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