Delayed-type hypersensitivity skin reactions due to heparins and heparinoids. Tolerance of recombinant hirudins and of the new synthetic anticoagulant fondaparinux

Eczema-like, infiltrated plaques at subcutaneous heparin-injection sites are well-documented side effects of these anticoagulants. They are due to delayed-type hypersensitivity. In 4 patients, patch, intradermal and subcutaneous tests were performed with a panel of unfractionated heparins (UFHs), low-molecular-weight heparins (LMWHs), heparinoids, recombinant hirudins and a new synthetic pentasaccharide anticoagulant fondaparinux sodium, to find safe alternatives. 3 patients were sensitized to all the UFHs and LMWHs. The LMWH tinzaparin sodium and the heparinoid pentosan polysulfate were found to be a possible substitute in patient no. 1 and 2, respectively. The recombinant hirudins and fondaparinux sodium were tolerated without any side effects in all patients tested. Fondaparinux is a synthetic copy of a pentasaccharide sequence in the heparin molecule. It is the first in a new class of antithrombotic agents. Our study suggests that it is a new safe alternative in patients with eczema-like, infiltrated plaques at subcutaneous heparin-injection sites.