The second international reference preparation of erythropoietin, human, urinary, for bioassay.

A collaborative study of the second international Reference Preparation of Erythropoietin, Human, Urinary, for Bioassay was carried out in 10 laboratories. Combined potency estimates obtained by comparison with the International Reference Preparation, indicate that ampoules of the second Preparation contain 10.0 IU (weighted mean potency) or, taking the unweighted mean potency, 9.8 IU, with fiducial limits (P=0.95) of 8.4-11.5 IU. The second Preparation could be used as a standard in estimating the potency of a preparation of sheep plasma erythropoietin (68/307) although, as with the International Reference Preparation, there was a tendency for the sheep plasma preparation to produce log-dose-log-response regression lines that were steeper than those produced by the second Preparation.In accelerated degradation studies of the second Preparation stored as the dry product in ampoules for up to 1 year, there was no consistent trend to indicate instability of the preparation.Following its establishment in 1971, the Second International Reference Preparation was allocated a potency of 10 IU/ampoule.