Phase-I Oxidative Biotransformation Reactions
Which of the following is a Phase 1 oxidative biotransformation reaction?
- Glucuronide conjugation
- Acetylation
- Sulfate conjugation
- Aliphatic/aromatic hydroxylation — Correct Answer
Explanation:
Correct Answer: Aliphatic and aromatic hydroxylation
Aliphatic and aromatic hydroxylation (e.g. of phenobarbital, phenytoin) is a Phase-I oxidative reaction catalyzed by the microsomal CYP 450 mixed function oxidase system.
Phase-I Reactions Include
- N- and O-dealkylation (phenacetin, morphine)
- Aliphatic and aromatic hydroxylation (phenobarbital, phenytoin)
- N-Oxidation (guanethidine, acetaminophen)
- Sulphoxide formation (chlorpromazine)
- Deamination (amphetamine)
- Hydrolysis of esters and amides (procaine)
- Azo reduction (prontosil) and Nitro reduction (chloramphenicol)
Phase-II Reactions
Conjugation reactions: glucuronidation, sulfation, acetylation, methylation, glycine conjugation, glutathione conjugation.
📚 About this Topic — Veterinary Pharmacology and Toxicology
This multiple choice question is from Veterinary Pharmacology and Toxicology, Veterinary Science. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Veterinary Pharmacology and Toxicology to strengthen your preparation.
