Impact of residual moisture and formulation on Factor VIII and Factor V recovery in lyophilized plasma reference materials.
Residual moisture content and formulation are important parameters when preparing lyophilized reference materials containing labile proteins. The protection of Factor VIII and Factor V activities were monitored in a lyophilized plasma preparation following formulation with either no additional excipient, 40 mM Hepes (4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid), 10 mg/mL glycine or a combination of 40 mM Hepes and 10 mg/mL glycine. The preservation of Factor VIII activity during freeze-drying was improved by the addition of either stabiliser and improved most, amongst the options studied, by the addition of both glycine and Hepes. The predicted stability at -20 degrees C and 20 degrees C was estimated using accelerated degradation studies. Although for plasma lyophilized alone there was some benefit from further desiccation over phosphorus pentoxide, resulting in very low moistures, for suitably formulated samples the predicted stability was as good for freeze-dried only samples as for those with further desiccation. This study emphasises the importance of optimum formulation on the stability of lyophilized proteins.