Heparin Other names: Unfractionated heparin

Drugs that interfere with platelet aggregation e.g. aspirin and other NSAIDs should be used with care due to increased risk of haemorrhage.

Increased risk of bleeding with oral anticoagulants, epoprostenol, clopidogrel, ticlopidine, streptokinase, dipyridamole, dextran solutions, abciximab, eptifibatide or any other drug which may interfere with coagulation.

Hyperkalaemia may occur with concomitant use of heparin with ACE inhibitors, angiotensin-II receptor antagonists or the renin inhibitor aliskiren.

Some cephalosporins, e.g. cefaclor, cefixime and ceftriaxone, can affect the coagulation process and may therefore increase the risk of haemorrhage when used concurrently with heparin.

Reduced activity of heparin has been reported with simultaneous intravenous glyceryl trinitrate infusion.

Avoid concomitant use of ketorolac even with low-dose heparin.

Probenecid may increase the anticoagulant effects of heparin.

Heparin can suppress adrenal secretion of aldosterone leading to hyperkalemia, particularly in patients such as those with diabetes mellitus, chronic renal failure, pre-existing metabolic acidosis, a raised plasma potassium, or taking potassium sparing drugs. The risk of hyperkalemia appears to increase with duration of therapy but is usually reversible. Plasma potassium should be measured in patients at risk before starting heparin therapy and in all patients treated for more than 7 days.

Platelet counts should be measured in patients receiving heparin treatment for longer than 5 days and the treatment should be stopped immediately in those who develop thrombocytopenia.

Heparin induced thrombocytopenia (HIT) and heparin induced thrombocytopenia with thrombosis (HITT) can occur up to several weeks after discontinuation of heparin therapy. Patients presenting with thrombocytopenia or thrombosis after discontinuation of heparin should be evaluated for HIT or HITT.

Nicotine may partially counteract the anticoagulant effect of heparin. Increased heparin dosage may be required in smokers.

In patients with advanced renal or hepatic disease, a reduction in dosage may be necessary.

Heparin is not contraindicated in pregnancy. Heparin does not cross the placent. The decision to use heparin in pregnancy should be taken after evaluation of the risk/benefit in any particular circumstances.

Osteoporosis has been reported with prolonged heparin treatment during pregnancy.

Particular caution is required at the time of delivery. Due to the risk of uteroplacental haemorrhage, heparin treatment should be stopped at the onset of labour.

If epidural anaesthesia is envisaged, heparin treatment should be suspended whenever possible.

Use in women with threatened abortion is contraindicated.

Heparin does not appear in breast milk.

None stated.