The formation of the desired enantiomer of pregabalin is ensured through the route of synthesis and confirmed by a chiral identity test. In addition, the R enantiomer is controlled as part of the specified impurities.
Particle size is part of the specification, but is not expected to be a critical parameter with regards to the bioavailability of the capsules, taking into account the water solubility of pregabalin. This has been confirmed by the broad range particle size distribution of drug substance lots used in clinical studies (see pharmaceutical development).
Specification limits have been adequately justified by analytical, stability and toxicity data. The analytical methods used in routine controls have been suitably described and validated.
Batch analysis data provided for 95 lots prepared using the commercial (n=91) and the development synthesis routes have shown no major differences, especially in term of impurity profiles. These data confirm satisfactory compliance and uniformity with the proposed specification.