Low molecular weight heparins copies: are they considered to be generics or biosimilars?

The protection rights of low molecular weight heparins (LMWHs) are expired or are expiring, so the extent and nature of the studies required to obtain a market authorization for LMWH copies represents a hot topic. FDA classifies LMWHs as semisynthetic drugs and their copies as generics whereas the EMA views them as biological medicines and consequently their copies as biosimilars. Consequently, FDA requires only in vivo pharmacodynamic studies, while EMA requires also clinical trials. The current work reviews the chemical composition and therapeutic indications of LMWHs available in the EU and USA markets to discuss the two different approaches. Because LMWHs show a high intrinsic variability and a complete characterization is not viable, a conservative approach is desirable.