Scale pharmaceutical process development

Anderson [2] presents a wide range of topics on pharmaceutical process development, including a number of different problems related to process scale-up, such as solvent and reagent selection, purification, and limitations to various operations. He notes that most reactors used for scale-up operations are selected for flexibility in running many different processes, especially for pilot plants and multiproduct manufacturing plants. 

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For the pharmaceutical industry, scale-up activities often refer to the scale-up of processes in pilot plants. More important, pharmaceutical process development frequently involves fitting a process to available plant equipment rather than designing an optimal plant for the manufacture of every drug substance in the pipeline. Only for the manufacture of commercially successful drugs is a dedicated plant designed and built. 

There is a distinction that some people recommend be made between process development and scale-up see, for example, Basu, P.K. et al.. Consider a new approach to pharmaceutical process development, CEP, August 1999, p. 82. 

The synthesis of aldehydes via hydroformylation of alkenes is an important industrial process used to produce in the region of 6 million tonnes a year of aldehydes. These compounds are used as intermediates in the manufacture of plasticizers, soaps, detergents and pharmaceutical products [7], While the majority of aldehydes prepared from alkene hydroformylation are done so in organic solvents, some research in 1975 showed that rhodium complexes with sulfonated phosphine ligands immobilized in water were able to hydroformylate propene with virtually complete retention of rhodium in the aqueous phase [8], Since catalyst loss is a major problem in the production of bulk chemicals of this nature, the process was scaled up, culminating in the Ruhrchemie-Rhone-Poulenc process for hydroformylation of propene, initially on a 120000 tonne per year scale [9], The development of this biphasic process represents one of the major transitions since the discovery of the hydroformylation reaction. The key transitions in this field include [10] ... 

The goal of this chapter is to provide a brief overview of standard engineering methods for process development and scale-up and discuss their applicability to the pharmaceutical industry. Model-based design methods and their impact on optimization, scale-up, and process control are discussed. The state of the art is contrasted to a realistic desirable state where these methods become part of a new standard of technological articulation. 

The chapter is organized as follows. First, to establish a common language, we define some common terms from both a pharmaceutical and an engineering perspective. Subsequently, we review model-based design and optimization as a framework for product and process development and optimization, process scale-up, and continuous improvement activities. The role of process and analytical technology (PAT) methods and principles in this framework is discussed. Finally, the main areas requiring effort are identified. 

The process of scale-up in the pharmaceutical industry generally involves moving a product from research and development into production. Numerous pitfalls could be met on this path. It is a well-known fact that often the production process cannot achieve the same product quality as was envisioned in the development and pre-approval stages. Losses in terms of effort and money can be enormous, which is why scale-up and postapproval changes are so important and so strictly regulated. 

He has been responsible for pharmaceutical product development from exploratory development, preclinical, preformulation, and drug delivery platform technologies, formulation, process, and scale-up manufacturing toward commercialization. 

The pilot-production phase may be carried out either as a shared responsibility between the development laboratories and its appropriate manufacturing counterpart or as a process demonstration by a separate, designated pilot-plant or process-development function. The two organization piloting options are presented separately in Figure 1. The creation of a separate pilot-plant or process-development unit has been favored in recent years because it is ideally suited to carry out process scale-up and/or validation assignments in a timely manner. On the other hand, the joint pilot-operation option provides direct communication between the development laboratory and pharmaceutical production. 

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