Safety of low molecular weight heparins in the treatment of venous thromboembolism.

Low molecular weight heparins (LMWHs) are commonly employed as a substitute for unfractionated heparin (UFH) in the treatment of venous thromboembolic events. Despite their higher cost, the preferential use of LMWHs seemed justified initially as, based on the results of earlier meta-analyses, these compounds were deemed to be more effective and safer than UFH. Although, in this respect, their purported superiority over UFH could not be confirmed by subsequent large, randomised trials and updated meta-analyses, other peculiar features of LMWHs were highlighted, favouring their preferential utilisation in patients with venous thromboembolism. Among these, the possibility of once-daily administration on an out-patient basis, the lower incidence of Type II heparin-induced thrombocytopenia and the lower likelihood of osteoporosis after prolonged treatment periods, appear to be especially prominent. This review attempts to evaluate the available evidence focusing on the safety of LMWHs for the treatment of venous thromboembolism and the current therapeutic options and potential advantages of LMWHs, either in general or in selected patient populations.