Heparin is a mucopolysaccharide prepared from ox lung or intestinal mucosa of ox, sheep or pigs. It can be produced physiologically e.g. by basophils and mast cells. It carries a negative charge at a normal pH.
It has a half life of about 1 hour, together with a narrow therapeutic range.
Usually the short half life means that overcoagulation is not life threatening. However, if there is torrential bleeding the effects can be reversed with protamine.
Patients on heparin for more than 5 days should have twice weekly platelet counts to check for heparin-induced thrombocytopaenia.
Last reviewed 01/2018