S-29 Frontier Study of Pharmacokinetics and Drug Metabolism on Development of Prodrug   S29-1. Structure, Function and Regulation of Carboxylesterase Isozymes Which Catalyze Metabolic Activation of Prodrugs   S29-2. Synergistic Role of Drug Metabolizing Enzymes and Transporters in Regulating the Extent of Oral Absorption   S29-3. Prodrug Design Based on Substrate Specificity of Carboxylesterase Isozymes   S29-4. A New Prodrug Strategy for Amino Compounds