Applications Other Than in the Pharmaceutical Industry

I 76 Applications Other Than in the Pharmaceutical Industry References... 

Process chemists thus play a crucial role in advancing both basic and applied chemistry. Given that man-made chemical products would not exist without their skills, it is odd and unfortunate that they rarely have much say in selecting the molecular targets for which they must devise practical commercial syntheses. Nowhere is the exclusion of process chemists from the discovery process more unfortunate than in the pharmaceutical industry. Here discovery takes the form of a sky s-the-limit search, wherein chemistry that is feasible, let alone ideal, for application on a practical scale is all but ignored. The pharmaceutical industry therefore needs more process chemists than any other field, and the challenges they face are by far the most daunting of chemists in any area of pure or applied chemistry. 

Several other applications of electiodialysis in the pharmaceutical industry have been studied on a laboratory scale [51]. Most of these applications are concerned with desalting solutions containing active agents which have to be separated, purified, or isolated from certain substrates [52]. Here, electrodialysis is often in competition with other separation procedures such as dialysis, solvent extraction, etc. In many cases, electrodialysis is the superior process as far as economics and the quality of the product is concerned. Especially the separation of amino acids and other organic acids by electrodialysis seems to be of interest to the pharmaceutical and chemical industry [53]. However, the deionization of cheese whey with an installed capacity of more than 35,000 square meters of membrane area for the production of more than 150,000 tons of desalted lactose per year is economically by far the most important application of electrodialysis in the food industry today. 

Examples of Synthesis Routes Inherently Safer Than Others As summarized by Bodor (1995), the ethyl ester of DDT is highly effective as a pesticide and is not as toxic. The ester is hydrolytically sensitive and metabolizes to nontoxic products. The deliberate introduction of a structure into the molecule which facilitates hydrolytic deactivation of the molecule to a safer form can be a key to creating a chemical product with the desired pesticide effects but without the undesired environmental effects. This technique is being used extensively in the pharmaceutical industry. It is applicable to other chemical industries as well. 

As gelatin is a common food additive with applications in the pharmaceutical industry, its introduction into foreign protein production systems may generate fewer regulatory concerns than other biopolymers. 

Currently there is a trend toward the synthesis and large-scale production of a single active enantiomer in the pharmaceutical industry [61-63]. In addition, in some cases a racemic drug formulation may contain an enantiomer that will be more potent (pharmacologically active) than the other enantiomer(s). For example, carvedilol, a drug that interacts with adrenoceptors, has one chiral center yielding two enantiomers. The (-)-enantiomer is a potent beta-receptor blocker while the (-i-)-enantiomer is about 100-fold weaker at the beta-receptor. Ketamine is an intravenous anesthetic where the (+)-enantiomer is more potent and less toxic than the (-)-enantiomer. Furthermore, the possibility of in vivo chiral inversion—that is, prochiral chiral, chiral nonchiral, chiral diastereoisomer, and chiral chiral transformations—could create critical issues in the interpretation of the metabolism and pharmacokinetics of the drug. Therefore, selective analytical methods for separations of enantionmers and diastereomers, where applicable, are inherently important. 

In the field of industrial pharmaceutical analysis the situation is different, because TLC instrumentation has reached a relatively high level. In some special application areas, such as the analysis of the extracts of medicinal plants, fermentation mixtures, etc., modem TLC (precoated or HPTLC layers, densitometric evaluation) has a distinct role, because the interference of so-called unknown background materials can be more easily eliminated than with other chromatographic techniques. Many chromatographers working in the pharmaceutical industry prefer to use reversed phase HPLC in conjunction with normal phase TLC or HPTLC to analyze raw materials for purity and impurities as well as for stability testing. 

Batch Crystallization Batch crystalhzation has been practiced longer than any other form of ciystaUization in both atmospheric tanks, which are either static or agitated, as well as in vacuum or pressure vessels. It is still widely practiced in the pharmaceutical and fine chemical industry or in those applications where the capacity is veiy small. The integrity of the batch with respect to composition and history can be maintained easily and the inventoiy management is more precise than with continuous processes. Batch ciystalhzers can be left unattended (overnight) if necessary and this is an important advantage for many small producers. 

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