Enzymoimmunoassays and related analytical techniques for drugs

Abstract

Radioimmunoassay (RIA) has a number of advantages as an analytical technique including its sensitivity, specificity, practicality and, in particular, wide applicability. Thus it is not surprising that, since the development of the first RIA for a drug, digitoxin (Smith et al. 1969), such assays have been introduced for over 60 drugs (Landon and Moffat, 1976), and have proved of great value to the clinical pharmacologist and clinician. Nonetheless, RIA has a number of disadvantages such as the need for radioisotope-counting equipment, a slight health hazard and, in the case of RIA based on gamma-emitting radioisotopes (such as ¹²⁵I), which have a relatively short half-life, the frequent need to prepare batches of the isotopically labelled drug, with consequent problems of quality control and distribution.