Megarin

Intravenous-
Prophylaxis of re-occlusion of the coronary arteries following thrombolytic therapy in myocardial infarction

• Adult: 60 U/kg (max: 4,000 U) or a bolus of 5,000 U if streptokinase was used, followed by 12 U/kg/hr (max: 1,000 U/hr) w/ a treatment duration of 48 hr.

Intravenous-
Peripheral arterial embolism, Unstable angina, Venous thromboembolism

• Adult: 75-80 U/kg or 5,000 U (10,000 U in severe pulmonary embolism) IV loading dose followed by 18 U/kg or 1,000-2,000 U/hr continuous infusion. Alternatively, intermittent inj of 5,000-10,000 U 4-6 hrly.
• Child: 50 U/kg loading dose, followed by an infusion of 15-25 U/kg/hr.
• Elderly: Lower dosages may be required.

Subcutaneous-
Prophylaxis of postoperative venous thromboembolism

• Adult: 5,000 U given 2 hr before surgery then 8-12 hrly for 7 days or until the patient is ambulant.

Subcutaneous-
Venous thromboembolism

• Adult: 15,000-20,000 U 12 hrly or 8,000-10,000 U 8 hrly.
• Child: 250 U/kg bid.
• Elderly: Lower dosages may be required.

Hypersensitivity reactions (e.g. chills, fever, urticaria, asthma, rhinitis); painful, ischaemic and cyanosed limbs; osteoporosis (in long-term admin), suppression of aldosterone synthesis leading to hyperkalaemia, cutaneous necrosis, delayed transient alopecia, priapism, rebound hyperlipaemia; increased serum concentrations of AST and ALT, prolonged prothrombin time; local irritation, erythema, mild pain, haematoma or ulceration on inj site.

Symptoms: Bleeding (nose bleeds, blood in urine or tarry stools may be noted as the 1st sign of bleeding).

Management: May give protamine sulfate by slow IV infusion over 10 min to treat severe bleeding (1 mg of protamine sulfate neutralises approx 100 U of heparin). Max: 50 mg as a single dose.

Heparin inhibits reactions that lead to the clotting of blood and the formation of fibrin clots both in vitro and in vivo. Heparin acts at multiple sites in the normal coagulation system. Small amounts of heparin in combination with antithrombin III (heparin cofactor) can inhibit thrombosis by inactivating activated Factor X and inhibiting the conversion of prothrombin to thrombin. Once active thrombosis has developed, larger amounts of heparin can inhibit further coagulation by inactivating thrombin and preventing the conversion of fibrinogen to fibrin. Heparin also prevents the formation of a stable fibrin clot in inhibiting the activation of the fibrin stabilizing factor.

Bleeding time is usually unaffected by heparin. Clotting time is prolonged by full therapeutic doses of heparin; in most cases, it is not measurably affected by low doses of heparin.

Patient with increased risk of bleeding complications, HTN, DM, pre-existing metabolic acidosis. Do not use in catheter lock flushing. Hepatic and renal impairment. Elderly. Pregnancy and lactation.

Parenteral anti-coagulants