Dangerous Drug: Warfarin Sodium(war’ far in)
Apo-Warfarin (CAN), Coumadin, Gen-Warfarin (CAN), Jantoven
PREGNANCY CATEGORY X
PREGNANCY CATEGORY D
(USE WITH MECHANICAL HEART VALVES)
Drug Classes
Coumarin derivative
Oral anticoagulant
Therapeutic Actions
Interferes with the hepatic synthesis of vitamin K–dependent clotting factors (factors II-prothrombin, VII, IX, and X), resulting in their eventual depletion and prolongation of clotting times.
Indications
Venous thrombosis and its extension, treatment, and prophylaxis
Treatment of thromboembolic complications of atrial fibrillation (AF) with embolization, and cardiac valve replacement
PE treatment and prophylaxis
Prophylaxis of systemic embolization after acute MI
Contraindications and Cautions
Contraindicated with allergy to warfarin; SBE; hemorrhagic disorders; TB; hepatic diseases; GI ulcers; renal disease; indwelling catheters, spinal puncture; aneurysm; diabetes; visceral carcinoma; uncontrolled hypertension; severe trauma (including recent or contemplated CNS, eye surgery; recent placement of IUD); threatened abortion, menometrorrhagia; pregnancy (fetal damage and death); lactation (suggest using heparin if anticoagulation is required).
Use cautiously with HF; diarrhea; fever; thyrotoxicosis; senile, psychotic, or depressed patients.
Available Forms
Tablets—1, 2, 2.5, 3, 4, 5, 6, 7.5, 10 mg; powder for injection—5 mg, reconstitutes to 2 mg/mL
Dosages
Dosage and administration must be individualized for each patient according to patient’s prothrombin time (PT) and INR response. Target of therapy is INR of 2–3 for AF, DVT, and PE or 2.5–3.5 for mechanical heart valve. IV use is reserved for situations in which oral warfarin is not feasible. Dosages are the same for oral and IV forms.
Dosages
Adults
Initially, 2–5 mg/day PO or IV. Adjust dosage according to patient response. For maintenance, 2–10 mg/day PO based on INR.
Geriatric patients
Lower doses are usually needed; begin with smaller doses than those recommended for adults, and closely monitor PT ratio or INR.
Pharmacokinetics
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