Generic drugs composition

In summary, it can be stated that the stationary phase and the mobile phase (buffer) pH are the most important factors determining the generic selectivity of a CS. The organic modifier composition and the column temperature can influence the selectivity locally, i.e., when separating a specific mixture of rather similar compounds, e.g., a drug impurity profile. 

Figure 9.11 Effect of disintegrant (Veegum ) on bioavailability of tolbutamide indicated by serum tolbutamide concentration. Two formulations were administered to healthy, non-diabetic subjects. One was a commercial product (Orinase) and the second was identical in composition and manufacturing method but contained 50% of the amount of disintegrant (Veegum). Varley AB (1968). The generic inequivalence of drugs. J Am Med Assoc 206 1745. Reprinted with permission of the American Medical Association.

A prime consideration in sample presentation has to be the purpose of the study. For instance in solids, one must decide whether the chemical structure of the solid is of singular importance, or whether its physical characteristics are of interest. If, for example, the requirement is to study polymorphism in drugs or minerals, or perhaps crystallinity or molecular orientation in polymers, then the integrity of these properties will need to be maintained throughout sample preparation, presentation, and measurement. Sample presentation methods that provide simple, rapid generic identification may prove inadequate for more detailed substructure investigations, such as compositional or conformational analyses. 

As an example, consider the drug losartan K (Cozaar), which is commonly prescribed for hypertension. The drug was invented by Dupont workers and developed and marketed with Merck Co. Inc. The patent [25] covering the composition expired in 2009 and the drug is now offered in generic form. Several early syntheses originated from 4 -methyl-biphenyl-2-carbonitrile. 

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