ABSTRACT
This chapter presents the concepts of a modern biopharmaceutical approach to orally administered prodrugs. It discusses the new opportunities that the continuous advancement in related fields, for example, molecular and computational biology, brings to the field of oral drug delivery via prodrug. Prodrugs must be converted to the active parent drug to exert the therapeutic effect. This activation process is not necessary specific; however, a good understanding of the possible activating enzymes will help the rational design of successful prodrugs. By considering enzyme-substrate specificity, it is possible to overcome poor site-specificity, leading to the desired higher efficacy accompanied by lower toxicity. The recent advances in biochemistry and molecular biology have delivered a lot of information on the function and expression of transporters and enzymes. Many transporters are expressed on the intestinal enterocytes that may be selectively targeted. The most important enzymes involved in the bioconversion of ester-based prodrugs include paraoxonase, carboxylesterase, acetylcholinesterase, and cholinesterase.
