Low molecular weight heparin: a better drug?

Preliminary clinical trials suggest that at least some low molecular weight (LMW) heparins are as effective as heparin in preventing post-operative deep vein thrombosis, and need only be injected once a day. However, a firm basis does not exist for assigning potency estimates to different LMW heparins. Caution is therefore necessary in determining appropriate dosages for various clinical indications. Until the problems of standardization and dosage are resolved, LMW heparins are unlikely to achieve their potential usefulness, or prove safer than standard heparin.