Caution is advised when administering heparin to patients at risk of haemorrhage (see section 4.3).
Heparin should be used with caution in patients with hypersensitivity to low molecular weight heparin.
Care should be taken when heparin is administered to patients with increased risk of bleeding complications, hypertension, renal or hepatic insufficiency. This list is not exhaustive.
The combination with medicinal products affecting platelet function or the coagulation system should be avoided or carefully monitored (see section 4.5).
In patients undergoing peridural or spinal anaesthesia or spinal puncture, the prophylactic use of heparin may be very rarely associated with epidural or spinal haematoma resulting in prolonged or permanent paralysis. The risk is increased by the use of a peridural or spinal catheter for anaesthesia, by the concomitant use of drugs affecting haemostasis such as non-steroidal anti-inflammatory drugs (NSAIDs), platelet inhibitors or anticoagulants, and by traumatic or repeated puncture.
In decision making on the interval between the last administration of heparin at prophylactic doses (≤15,000 IU/day) and the placement or removal of a peridural or spinal catheter, the product characteristics and the patient profile should be taken into account. Placement or removal of a peridural or spinal catheter should not be allowed until 4-6 hours after the last heparin administration and subsequent dose should not take place before at least 1 hour post procedure. For treatment doses (>15,000 IU/day), placement or removal of a peridural or spinal catheter should not be allowed until 4-6 hours after last intravenous heparin administration or 8-12 hours after last subcutaneous heparin administration. Re-administration should be delayed until the surgical procedure is completed or at least 1 hour post procedure.
Should a physician decide to administer anti-coagulation in the context of peridural or spinal anaesthesia, extreme vigilance and frequent monitoring must be exercised to detect any signs and symptoms of neurologic impairment, such as back pain, sensory and motor deficits and bowel or bladder dysfunction. Patients should be instructed to inform immediately a nurse or a clinician if they experience any of these. If signs or symptoms of epidural or spinal haematoma are suspected, urgent diagnosis and treatment including spinal cord decompression should be initiated.
Heparin should not be administered by intramuscular injection due to the risk of haematoma. Due to the risk of haematoma, concomitant intramuscular injections should also be avoided.
Because of the risk of immune-mediated heparin-induced thrombocytopenia (type II), platelet count should be measured before the start of treatment and periodically thereafter. Heparin must be discontinued in patients who develop immune-mediated heparin induced thrombocytopenia (type II) (see sections 4.3 and 4.8). Platelet counts will usually normalise within 2 to 4 weeks after withdrawal.
Low molecular weight heparin should not be used as an alternative to heparin in case of heparin-induced thrombocytopenia (type II). Heparin induced thrombocytopenia and heparin induced thrombocytopenia with thrombosis 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 and HITT.
Heparin products can suppress adrenal secretion of aldosterone leading to hyperkalaemia (see section 4.8). Risk factors include diabetes mellitus, chronic renal failure, pre-existing metabolic acidosis, raised plasma potassium at pre-treatment, concomitant therapy with drugs that may elevate plasma potassium and long-term use of heparin (see section 4.5).
In patients at risk, potassium levels should be measured before starting heparin and monitored regularly thereafter, particularly if treatment is prolonged beyond about 7 days. Heparin-related hyperkalaemia is usually reversible upon treatment discontinuation, though other approaches may need to be considered if heparin treatment is considered lifesaving (e.g. decreasing potassium intake, discontinuing other drugs that may affect potassium balance).
Excipients
Heparin contains benzyl alcohol, methyl- and propyl parahydroxybenzoate and sodium as excipients. Methyl- and propyl parahydroxybenzoate may cause allergic reactions (possibly delayed), and exceptionally, bronchospasm.
Benzyl alcohol may cause allergic reactions.
Intravenous administration of benzyl alcohol can lead to adverse reactions and death in infants (gasping syndrome) and must not be used for infants younger than 4 weeks of age (see section 4.3). It is not known at which amount benzyl alcohol is toxic. Due to risk of accumulation of benzyl alcohol, this medicine should not be used for more than one week in children up to 3 years old.
Extra caution is advised if high doses of benzyl alcohol are used, especially in patients with reduced liver- and kidney function due to risk of accumulation and toxicity (metabolic acidosis). High doses may only be administered if necessary.
Heparin contains 4.1 mg sodium/ml which is less than 1 mmol sodium (23 mg), that is to say essentially 'sodium-free' for doses up to 5 ml (corresponding to 5,000 IU heparin sodium).
Heparin contains 41 mg sodium per 10 ml vial. This corresponds to 2.1 % of the WHO recommended maximum daily intake of 2 g for an adult.