Analytical Aspects of Drug Delivery: An Important and Often Overlooked Problem

Abstract

A flurry of activity has recently taken place aimed at developing improved delivery systems for drugs. Such systems are being designed to release drugs at controlled rates, to selectively direct the agent to appropriate “target sites” (located either within or on the surfaces of particular cell types) while reducing drug exposure to “non-target” areas and to control the absorption, transport, distribution and cellular uptake of pharmacologically active agents. The motivation for these efforts include: (1) the realization that many candidate drugs that have been found clinically unsuitable would be therapeutically and commerically valuable if properly delivered, (2) interest in developing products derived from genetic engineering (and other compounds) as drugs whose potency, short biological and/or chemical half lives or peculiar disposition profiles necessitate controlled, regiospecific release from a formulation, (3) potential exploitation of cytotoxic agents (or other materials) with narrow therapeutic indices requiring precise temporal and spacial control of drug release, (4) therapeutic advantage gained by less fluctuation in drug levels, better patient compliance and ultimately “personalized” systems whose release program is responsive to physiological/pharmacological events and (5) marketing considerations.