The European Pharmacopoeia (Ph. Eur.) monograph for somatropin 1) (recombinant DNA-derivedhuman growth hormone) no longer includes an in vivo bioassay. This important step is the resultof an international collaborative study initiated by the National Institute for Biological Standardsand Control (NIBSC) in collaboration with the European Pharmacopoeia 2). The study wasinitiated in 1992. The results showed that the in vivo bioassay could be removed from routinebatch controls without reducing safety, and were presented during an international workshopon somatropin)