Sources of biopharmaceuticals

Many microorganisms represent attractive potential production systems for therapeutic proteins. They can usually be cultured in large quantities, inexpensively and in a short time, by standard methods of fermentation. Production facilities can be constructed in any world region, and the scale of production can be varied as required. 

The expression of recombinant proteins in cells in which they do not naturally occur is termed heterologous protein production . By far the most common microbial species used to produce 

Animal cell culture (particularly CHO and BHK cell lines) 

Transgenic animals (focus thus far is upon sheep and goats) 

Biopharmaceutical product Source Biopharmaceutical product Source 

This chapter aims to overview the manufacturing process of therapeutic proteins. It concerns itself with two major themes (1) sources of biopharmaceuticals and (2) upstream processing. The additional elements of biopharmaceutical manufacturing, i.e. downstream processing and product analysis, are discussed in Chapters 6 and 7 respectively. 

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Plants are a potentially cheap source of biopharmaceuticals. It has been estimated that the manufacturing costs for recombinant proteins in plants could be 10- to 50-fold lower than the same product obtained by fermentation with E. coll and subsequent recovery. 

The three main sources of competitive advantage in the manufacture of high value protein products are first to market, high product quaUty, and low cost (3). The first company to market a new protein biopharmaceutical, and the first to gain patent protection, enjoys a substantial advantage. The second company to enter the market may find itself enjoying only one-tenth of the sales. In the absence of patent protection, product differentiation becomes very important. Differentiation reflects a product that is purer, more active, or has a greater lot-to-lot consistency. 

Insulin was originally (since the 1930s) obtained from porcine and bovine extracts. Bovine insulin differs from human insulin by three amino acids, and it can elicit an antibody response that reduces its effectiveness. Porcine insulin, however, differs in only one amino acid. An enzymatic process can yield insulin identical to the human form. Currently, insulin is produced via the rDNA process it was the first recombinant biopharmaceutical approved by the FDA in 1982. The recombinant insulin removes the reliance on animal sources of insulin and ensures that reliable and consistent insulin is manufactured under controlled manufacturing processes. A description of diabetes meUitus and insulin is presented in Exhibit 4.13. 

The last section of this chapter is devoted to the regulatory aspects of oral drug absorption and in particular to the biopharmaceutics classification system and the relevant FDA guideline. At the very end of the chapter, we mention the difference between randomness and chaotic behavior as sources of the variability encountered in bioavailability and bioequivalence studies. 

Source The main source of the information in this table is either the Food and Drug Administration (FDA) Web site or European Medicines Agency (EMEA) Web site. For biopharmaceuticals approved before 1995 limited information is available so the author used the most recent label (package insert) to derive the reproductive, carcinogeneticity, and genetic toxicology studies completed for marketing approval. 

An important fact inherent in the purity analysis of a recombinant pharmaceutical is that the absolute purity of any protein is an elusive, if not an unobtainable, measurement. For biopharmaceuticals, purity is a relative term. Protein purity is method-dependent and is defined by the shortcomings of the analytical procedure. Also, unlike small traditional drugs, proteins are highly complex molecules. For these two reasons, more than one method must be utilized to define a protein s purity. The greater the number of methods used in the purity analysis, the greater the assurance is that the product is pure. Furthermore, the purity determined by an analytical method can only be properly interpreted based on the method s validation. Analytical methods validation is critical to and inseparable from purity determinations. A detailed discussion on analytical methods validation is beyond the scope of this chapter but other sources of information are available for the interested reader.11 13... 

The production of proteins is associated with risks of either introducing substances with adverse effects, or failing to achieve total removal of impurity, or both. Potential contamination with adventitious agents is actually one of the main concerns for the product safety of biopharmaceuticals. This situation is extendible to antibodies, whether they are monoclonal or polyclonal, since they are isolated from various biological liquids (see Section III), which are themselves considered as potential sources of risk. 

Biopharmaceutical clean-rooms typically house process equipment requiring utilities such as pure water, electricity, vacuum, and clean compressed air. The source of these utilities is usually outside the clean room. During the design phase a utility matrix is developed, in conjunction with end users and equipment manufacturers, identifying all equipment and the utilities required. This is the basis for determining the capacity of the utility systems as well as the point-of-use location of specific utilities. 

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