The Second International Standard for somatropin (recombinant DNA-derived human growth hormone): preparation and calibration in an international collaborative study.

A preparation of somatropin (recombinant DNA-derived human growth hormone) was prepared as lyophilised ampoules according to WHO procedures for international biological standards. The candidate preparation (98/574) was evaluated in an international collaborative study (16 laboratories, nine countries), with the following aims: (i) to determine the suitability of the preparation to serve as the International Standard for somatropin by studying its performance in the current range of physico-chemical and biological assay methods employed for somatropin; (ii) to assign a content in terms of the existing (first) International Standard for somatropin, using the currently recognised assay procedure (Size Exclusion High Performance Liquid Chromatography, SE HPLC); (iii) to confirm the specific biological activity of the candidate preparation; (iv) to confirm the stability of the candidate preparation. On the basis of the collaborative study WHO agreed that: the preparation in ampoules coded 98/574 is suitable to serve as the next WHO International Standard for somatropin; the preparation in ampoules coded 98/574 should be established as the second International Standard for somatropin, with a defined ampoule content of 1.95 mg total somatropin plus somatropin-related proteins per ampoule; the specific activity of the preparation should be defined as 3.0 IU/mg somatropin. Copyright 2001 The International Association for Biologicals.