Heparon

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.

Enhanced anticoagulant effect with other drugs affecting platelet function or the coagulation system (e.g. platelet aggregation inhibitors, thrombolytic agents, salicylates, NSAIDs, vit K antagonists, dextrans, activated protein C). Decreased anticoagulant effect with gyceryl trinitrate infusion. Increased risk of hyperkalaemia with ACE inhibitors or angiotensin II antagonists.

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.

Pregnancy Category C. Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.

Nursing Mothers: Due to its large molecular weight, heparin is not likely to be excreted in human milk, and any heparin in milk would not be orally absorbed by a nursing infant. Benzyl alcohol present in maternal serum is likely to cross into human milk and may be orally absorbed by a nursing infant. Exercise caution when administering Heparin Sodium Injection to a nursing mother.

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.

Pediatric Use: There are no adequate and well controlled studies on heparin use in pediatric patients. Pediatric dosing recommendations are based on clinical experience. Carefully examine all Heparin Sodium Injection vials to confirm choice of the correct strength prior to administration of the drug. Pediatric patients, including neonates, have died as a result of medication errors in which vials have been confused with “catheter lock flush” vials

Parenteral anti-coagulants

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.

Store between 20-25° C. Protect from freezing.