Coumarins & Indanediones(Acenocoumarol, Phenindione, Warfarin)

(Aceno- coumarol, Phenindione, Warfarin) : They act indirectly by interfering with the synthesis of Vit. K dependent clotting factors in liver. They apparently behave as competitive antagonists of Vit. K and reduce the plasma levels of functional clotting factors in a dose dependent manner.

Indications

Venous thrombosis, pulmonary embolism, atrial fibrillation with embolisation.

Dosage

300 mg the first day, 200 mg the second day, and 100 mg the third day.

Contra-Indications

Pregnancy, lactation. Hepatic or renal impairment. History of Peptic ulcer, cerebrovascular haemorrhage.

Special Precautions

Hypertension, weight changes, elderly acute illness, Vit k deficiency.

Side Effects

Rash, fever, diarrhoea, alopecia, agranulocytosis, hepatitis.

Drug Interactions

Addition or deletion of any drug from the therapeutic regimen of patients receiving oral anticoagulants may affect patient response to the anticoagulant. Frequent determination of prothrombin time and close monitoring of the patient is essential to ascertain when adjustment of dosage of anticoagulant may be needed.