ACE inhibitors and Angiotensin II receptor antagonists + Heparins

ACE inhibitors and Angiotensin II receptor antagonists + Heparins

Heparin may increase the risk of hyperkalaemia with ACE inhibitors or angiotensin II receptor antagonists.
Clinical evidence, mechanism, importance and management An extensive review of the literature found that heparin (both unfractionated and low-molecular-weight heparins) and heparinoids inhibit the secretion of aldosterone, which can cause hyperkalaemia.1 The CSM in the UK suggests that plasma-potassium levels should be measured in all patients with risk factors (including those taking potassium-sparing drugs) before starting heparin, and monitored regularly thereafter, particularly if heparin is to be continued for more than 7 days.2 Note that ACE inhibitors and angiotensin II receptor antagonists are potassium sparing, via their effects on aldosterone. Some workers1 have suggested that the monitoring interval should probably be no greater than 4 days in patients at a relatively high risk of hyperkalaemia. Other risk factors include renal impairment, diabetes mellitus, pre-existing acidosis or raised plasma potassium.2 If hyperkalaemia occurs, the offending drugs should be stopped (although this may not be practical in the case of heparin). When the hyperkalaemia has been corrected (by whatever medical intervention is deemed appropriate) the drugs can cautiously be reintroduced.
1. Oster JR, Singer I, Fishman LM. Heparin-induced aldosterone suppression and hyperkalemia.
Am J Med (1995) 98, 575–86.
2. Committee on Safety of Medicines/Medicines Control Agency. Suppression of aldosterone secretion by heparin. Current Problems (1999) 25, 6.