Analytical Methods

Abstract

It is becoming increasingly obvious in clinical studies of the elderly that the quantitation of drugs and/or their metabolites in biological fluids should be an integral part of trial designs.¹ Serum drug concentrations often provide unique answers to important questions pertaining to the pharmacokinetics and pharmacodynamics of therapeutic agents. Good drug assay data may be helpful not only in elucidating the disposition characteristics of drugs, but also in the discovery of metabolites as new therapeutic moieties. Serum drug concentrations may correlate with therapeutic or toxic effects of drugs and that may help define mechanisms of drug action. The technological revolution in analytical methodology occurring during the past decade has provided the clinical investigator with an exciting array of assay tools for identification and quantitation of drugs and metabolites in various body fluids. To utilize this technology optimally the clinical investigator needs to have a basic understanding of the principles of drug analysis and quality control. It is important to recognize that the overall inherent quality of a clinical study that includes drug concentration determinations can be no better than the quality of the assay methods used in the laboratory. Clearly, one must pay close attention to the details of assay procedures and any special analytical concerns invoked by geriatric clinical studies.