Which statement best describes Phase 2 metabolism?

Which statement best describes Phase 2 metabolism?

• A. Phase 1: oxidation, reduction, hydrolysis; Phase 2: conjugation
• B. Phase 1: oxidation and reduction; Phase 2: hydrolysis and conjugation
• C. Phase 1: oxidation, reduction; Phase 2: hydrolysis
• D. Phase 1: oxidation, reduction, hydrolysis; Phase 2: oxidation

Answer: (A)

Drug metabolism happens in two broad stages to make compounds easier to excrete. In Phase 1, reactions such as oxidation, reduction, and hydrolysis modify the drug to introduce or uncover polar functional groups. In Phase 2, the drug (or its Phase 1 metabolite) is conjugated with another molecule—glucuronic acid, sulfate, glycine, glutamine, acetyl groups, and similar partners—producing a highly water-soluble compound ready for elimination. The best description here is that Phase 1 involves oxidation, reduction, and hydrolysis, while Phase 2 involves conjugation. This captures the proper sequence and the types of reactions characteristic of each phase. The other statements mix up where hydrolysis or oxidation belongs or incorrectly assign oxidation to Phase 2, which is not how these phases are organized.

Drug metabolism happens in two broad stages to make compounds easier to excrete. In Phase 1, reactions such as oxidation, reduction, and hydrolysis modify the drug to introduce or uncover polar functional groups. In Phase 2, the drug (or its Phase 1 metabolite) is conjugated with another molecule—glucuronic acid, sulfate, glycine, glutamine, acetyl groups, and similar partners—producing a highly water-soluble compound ready for elimination.

The best description here is that Phase 1 involves oxidation, reduction, and hydrolysis, while Phase 2 involves conjugation. This captures the proper sequence and the types of reactions characteristic of each phase.

The other statements mix up where hydrolysis or oxidation belongs or incorrectly assign oxidation to Phase 2, which is not how these phases are organized.