The use of flow microfluorometry for pharmaceutical testing.
The techniques and procedures of rapid flow microfluorometry (FMF) in the development and testing of pharmaceuticals can be useful in the following ways: (1) cell identification and use of more precise and accurate endpoints of cell viability in cytotoxicity screening assays; (2) faster methods for determining total cellular protein, diameter, and volume in fixed cells and lymphocytes obtained in clinical studies, and adjustment of dosing regimens may be made rapidly based on such analyses; (3) studies of cellular nucleic acid content, mitotic cell progression, and growth in drug-treated cell populations, and investigations conducted on whether a particular drug is acting on a sensitive cell population or whether its effects are consistent throughout a particular group of cells or tissues; (4) measurement of drug penetration, uptake, concentration, resistance, and cell cycle specificity in cells and tissues, and (5) automated scoring of chromosome number, ploidy, and aberrations in treated cells as additional evidence of toxic activity of pharmaceutical substances. The binding of drugs to cellular macromolecules and other structures can result in a multiplicity of effects on cell growth, metabolism, chromosome content, morphology, and neoplastic potential. The methods and results described in this review can be used individually and in combination, along with commonly used techniques. It is hoped that an integrated approach to basic cellular biology, pharmacology, physiology, genetics, and toxicology as applied to drug development and testing can be furthered through use of FMF. Caution must be exercised, however, in extrapolating results found in one study of chemotherapeutic efficacy to other circumstances of clinical practice, since interindividual differences in response are not abrogated by this new technology. The introduction of flow microfluorometry is likely to engender a significant delay in its validation by the Food and Drug Administration as a means of generating data suitable for support of approval of the pharmaceutical products and processes that it regulates. This is due to the complex theoretical considerations associated with FMF and the attendant need for instrument familiarization and training of Food and Drug Administration reviewers. As with any new technology, time must pass and further experimentation be conducted before a laboratory method can become a universally accepted, commercially useful, and viable technique.