This chapter is a detailed account of drug metabolism, prodrugs and related
terminology that are critical knowledge base for pharmacist and pharmacy education.
After study of this chapter, students will be able to:
• Comprehend the fundamental concepts of drug metabolism
• Describe the significance of drug metabolism
• Identify key enzymes involved and the sites of drug metabolism
• Explain phase I and phase II metabolic pathways, including:
♦ Phase I (Functionalization)
- Oxidation of aromatic moieties, olefins, benzylic & allylic C atoms and α-C of C=O
and C=N, aliphatic and alicyclic C, C-heteroatom system, C-N (N-dealkylation, Noxide
formation, N-hydroxylation), C-O (O-dealkylation), C-S (S-dealkylation, Soxidation,
desulfuration), alcohols and aldehydes, and miscellaneous oxidative
reactions
- Reduction of aldehydes and ketones, Nitro and azo compounds, and miscellaneous
reductive metabolisms
- Hydrolytic reactions of esters and amides, epoxides and arene oxides by epoxide
hydrase
♦ Phase II (Conjugation)
- Glucuronic acid conjugation, sulfate conjugation, glycine and other amino acid,
glutathione or mercapturic acid, acetylation, methylation
- Define and differentiate between prodrug, soft drug and antedrugs
- Discuss metabolic routes of some individual drugs
Keywords: Antedrug, Conjugation, Drug interactions, Drug metabolism,
Enterohepatic circulation, First pass effect, Phase I metabolism, Phase II
metabolism, Prodrug, Soft drug.
