Fundamentals of Drug Delivery

Drug delivery systems have the potential of deciding the efficiency of a therapeutic agent. The potential of a drug is often limited by the lack of effective delivery systems and therefore, past few years have seen tremendous upsurge in the research oriented towards development of different systems for the drug delivery systems. From the development of orally administered pills to nanoparticles-based delivery systems, the technologies for drug deliveries have come a long way. The first big success is the development of biological, chemical and physical means that are adopted to alter the pharmacokinetic properties of the drug to exhibit the desired pharmacological effect and remove undesirable physiochemical properties. Development in drug delivery systems can be described through different phases which are described as different generations of the drug delivery system. Sustained gradual release is the first generation of control drug release practice in which a drug is packed in a capsule or in the form of a capsule that releases drug with it when mixed with water in the stomach. On the other hand, targeted drug delivery system is a special system of drug delivery in which the drug is selectively targeted only to the site of action/absorption and not to the non-target tissues, cells or organ. This chapter provides a glimpse of various physiochemical and biological barriers that restrict effective drug delivery and the techniques adopted to overcome these barriers for effective drug delivery.