[Percutaneous absorption of heparin: a critical review of experimental results]

Percutaneous penetration of heparin is limited by its large molecular weight, negative charge and hydrophilicity. Although some authors did not find any significant anticoagulant effect of transdermally delivered heparin but several other papers indicate that heparin penetrates the skin barrier. The actual article provides a critical review of the in vitro and in vivo studies on percutaneous absorption of heparin and heparinoids. It is concluded that there is no sufficient evidence that heparin is able to penetrate intact skin. However under clinical conditions the integrity of the skin barrier may be changed what results in promotion of heparin penetration and justifies usage of topical drug formulations like ointments and gels.