Question

The following are the Phase-II Biotransformation reactions, except

• A. Glucuronidation
• B. Acetylation
• C. Oxidation
• D. Methylation

Hint:

Phase I = OH (Oxidation, Hydrolysis, Reduction). Phase II = Conjugation.

Answer 1

The Correct Option is C

Step 1: Concept
Drug metabolism generally occurs in two phases: Phase I (nonsynthetic) and Phase II (synthetic/conjugation).

Step 2: Meaning
Phase II reactions involve the attachment of an endogenous group (like glucuronic acid or acetate) to the drug to make it water-soluble.

Step 3: Analysis
Glucuronidation, Acetylation, and Methylation are all conjugation reactions belonging to Phase II. Oxidation, along with reduction and hydrolysis, is a Phase I reaction that introduces or unmasks a functional group.

Step 4: Conclusion
Oxidation is not a Phase II reaction; it is a Phase I biotransformation.

Final Answer: (C)