Collaborative study for the establishment of XXXX vaccine (adsorbed) Third International Standard and European Pharmacopoeia Biological Reference Preparation batch no. 2.

@entity1 @entity19 @entity840 @entity116 @entity912
The aim of the present collaborative study was to calibrate two candidate replacement standards for @entity116 vaccine for @entity1 use in the terms of the Second International Standard (IS) for @entity116 Toxoid, Adsorbed (TEXA-2) using challenge potency assays in @entity840 and @entity19 and to establish the 3rd IS and the Ph. Eur. BRP batch 2. Two test preparations (coded B and C) were included as candidate replacement for TEXA-2 and Ph. Eur. BRP batch 1 (EBRP-1). This project was run as a joint WHO/Ph. Eur. study. Twenty-seven laboratories representing nineteen countries participated in the study. Twenty-three laboratories performed assays in @entity19 (11 laboratories performed lethal, 11 @entity912 , and one serology assays) and fourteen laboratories performed assays in @entity840 (10 laboratories performed lethal and 4 @entity912 assays). Estimates of potency, expressed in ampoule of TEXA-2 per ampoule of candidate replacement standards were two-fold higher in @entity19 than in @entity840 . However, using the assumed relationship between TEXA-1 and TEXA-2 in @entity19 and @entity840 (Lyng and Nyerges, 1984), potency estimates for candidate replacement standards (sample coded B and C), in terms of TEXA-1, gives estimates which are similar in both animal models. Stability was assessed within the collaborative study for candidate standard B. On the basis of this collaborative study, the ECBS of WHO has established the candidate material coded B as the Third IS for @entity116 Toxoid, Adsorbed, with an assigned unitage of 469 IU/ampoule, based on its calibration by @entity840 challenge assays (WHO report BS/00.1932). Further studies were organised to assess which of the two candidate standards is most suitable as replacement for EBRP-1. Manufacturers were asked to include candidate B and candidate C in their routine quality control potency assays of @entity116 vaccines in order to assess the impact of the use of either preparation on their calibration results. The features and results of this additional phase are described at the end of this report in a separate section entitled "Choice of replacement batch for EBRP-1". Based on these results, at the session in March 2001, the Ph. Eur. Commission adopted candidate B as the @entity116 vaccine (adsorbed) Ph. Eur. BRP Batch 2 with assigned potencies of 469 IU/ampoule for the @entity840 assays and 496 IU/ampoule for the @entity19 assays.
