An overview of on‐line systems using drug metabolizing enzymes integrated into capillary electrophoresis

Enzymatic assays using CE are now among the most noteworthy applications of this analytical technique in pharmacology‐related investigations. Studies of metabolic pathways of new chemical entities mediated by drug metabolizing enzymes are attracting particular attention. Conventional CE‐based enzymatic in vitro assays are generally restricted to the separation of reagents after incubation performed off‐line. EMMA represents an alternative and fully prospective approach, allowing injection, reaction, separation, and detection to be conducted in a single capillary. Such an on‐line system—in contrast to the standard approach—enables automation, miniaturization, and a significant reduction in reagent volumes, resulting in a very robust and cost‐efficient method. Hence, EMMA could be a method of choice for the screening of new drugs, enzymatic inhibitors, and putative drug–drug interactions. This review provides a summary of reports covering the area of EMMA‐based and related methods implemented into in vitro studies of drug metabolizing enzymes. A general description of the EMMA framework, enzyme families, and a concise discussion of the prognosis for the development of this methodology are given as well.