Potency assay of epoetin alpha: Comparison of Swiss Webster, NIH, C57BL/6, BALB/c mice with the hybrid B6D2F1

In this study we compared the outcomes of epoetin alpha (rhEPO) potency assays performed with Swiss Webster, NIH, C57BL/6 and BALB/c mice with those of the assay conducted with the B6D2F1 hybrid, the only mice recommended by the European Pharmacopoeia (EP). Female mice from different breeding stocks and strains, weighing 16-18 g, received a single subcutaneous injection of (30, 90 or 270 IU per mouse, 0.2 mL per mouse) of rhEPO. Biological potencies 4000 IU/mL rhEPO pharmaceutical forms from different batches were determined using a biological reference preparation (3773 IU/mL) previously tested against the international reference standard BRP (European Pharmacopoeia Biological Reference Preparation). Results showed that assays with mice from all tested breeding stocks and strains met EP statistical criteria for a valid erythropoietin potency assay and thus they are potential alternatives to the use of B6D2F1 hybrids. The assays with BALB/c mice, however, were those the results of which were most similar to those obtained with the hybrid regarding average reticulocyte counts in response to 30, 90 and 270 IU/mouse, angular (slope) and linear (intersection) coefficients of the linear dose-response curve (parallel and almost complete overlapping dose-response curves).