Stability evaluation of live attenuated Japanese encephalitis vaccine

Abstract

Objective To evaluate the stability of live attenuated Japanese encephalitis vaccine (JEV) product. Methods Two specifications (1- and 5-single human dose) of JEV were selected and stored at (25±2) and (37±2) ℃ in accelerated stability study, or at 2-8 ℃ in long-term stability study. Critical quality indicators were tested. Regression analysis was conducted using the long-term stability data. Results Four batches of 1- and 2 batches of 5-single human dose JEV were stored at (25±2) ℃, relative humidity (RH) (60±5)% for 3 months and (37±2) ℃, RH (75±5)% for 14 d, and their physical appearance, virus titer, moisture content and pH all met standards. All results from 9 batches of 1- and 7 batches of 5-single human dose vaccines stored at 2-8 ℃ for 24 months met standards. Regression analysis showed that, in average, for each prolonged storage month at 2-8 ℃, the virus titer of 1- and 5-single human dose vaccines decreased by 0.020 and 0.017 lg plaque-forming unit/ml, while the moisture content increased by 0.055% and 0.047%, respectively. The validity period calculated by the 95% confidence interval of dependent variable average in the regression equation was much longer than the validity period (18 months) specified in current registration standard. Conclusion The tested JEV product is stable, safe and reliable. Key words: Japanese encephalitis vaccine; Period of validity; Drug stability; Evaluation studies