Their article presents an overview of the implementation of key elements (such as Target Product Profile, Critical Quality Attributes, design space and control strategy) of QbD – a systemic approach in the case of generic drugs.

The basis for this concept is that advanced understanding of variables affecting generic drug (product) quality, either obtained through historical operation or demonstrated through process modelling, justifies the replacement of the traditional process targets with acceptable operational ranges.

Dr Varu and Dr Khanna also describe the steps involved in the development of generic drugs, steps through which the QbD concept can be applied, and the opportunities for and challenges to implementing QbD in generic drug development.

In an article by Dr Lawrence X Yu and Dr Robert Lionberger of the FDA, published in Pharmaceutical Technology of 2 October 2009, QbD for generic-drug products is also discussed, based on a two-day workshop in June 2009 in Maryland, USA, organised by the FDA's Office of Generic Drugs (OGD) and the Generic Pharmaceutical Association (GPhA). The issues include: (1) The quality target product profile (QTPP) and critical quality attributes (CQAs); (2) Drug substance and excipient properties; (3) Formulation design and development; (4) Manufacturing process design and development; (5) Identification of critical process parameters (CPPs) and critical material attributes (CMAs); (6) Risk assessment and design space; and (7) Scale-up and control strategy.

Dr Yu and Dr Lionberger believe that Abbreviated New Drug Applications (ANDAs) should include these elements. According to them, the following topics require further discussion: (1) The QTPP; (2) Use of prior knowledge in formulation and process design and development; and (3) Regulatory evaluation of generic-drug sponsors' risk assessment and mitigation plans as well as control strategy.

References:

Ramaji K Varu and Amit Khanna. Opportunities and challenges to implementing Quality by Design approach in generic drug development. J Generic Med 2010 7: 60-73. published online 17 November 2009.

Lawrence X Yu, Robert Lionberger et al. Quality by Design for Generic Drugs. Pharmaceutical Technology. 33:10, pp. 122-7. 2009 October 2.