Characterization studies undesired effects

Adverse reaction. Unwanted effect(s) (i.e., physical and psychological symptoms and signs) resulting from treatment. A less rigid definition of adverse reaction includes the previous definition plus any undesirable effect or problem that is present during the period of treatment and may or may not be a well-known or obvious complication of the disease itself. Thus, many common personality, physical, psychological, and behavioral characteristics that are observed in medicine studies are sometimes characterized as adverse reactions even if they were present during baseline. 

For normal chemical systems, the characterization of mixtures of compounds is undesirable and generally unnecessary if means of separation of the components are available. However, photochromic systems inherently display properties of mixtures except when the system is completely converted to either of its forms. This causes measurements of heats of combustion, photoelectric effects, and electrical conductivity to be particularly difficult. A variety of such studies is presented in the following sections to illustrate the utility of these measurements. 

Overall, pharmacogenomic studies play an increasing important role in the molecular characterization of the therapeutic potential of novel chemical compounds, as well as the determination of undesirable/possibly detrimental effects (Fig. 2). 

As mentioned in connection with the need for laboratory experiments, pilot-plant tests also help to identify potential problems that arise from small quantities of impurities in the feed streams, and when unanticipated byproducts are produced, usually in small quantities, that have adverse effects, such as to impart an undesired color or smell to the product. When a catalyst is used, the impact of these species needs to be studied, and, in general, the useful life of the catalyst needs to be characterized. Pilot plants can also verify separation schemes developed during process design. 

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