Phase II drug degradation reactions involves linking of conjugates to the drugs are ___

A) Glutathione

B) Glycine

C) Both (a) & (b)

D) None of these

Hi!

The answer is (C) Both (a) and (b)

Explanation:

Drug Metabolism:

Drug metabolism is divided into two steps: Phase 1 and Phase 2 reactions. Phase 1 reactions involve the degradation or formation of functional groups. Phase 2 reactions involve the conjugation of the drug or its Phase 1 intermediate with a polar conjugating molecule. Phase 2 generally performs the detoxification step in the drug degradation process. Phase 2 or conjugation reactions are further divided into 2 types: Type 1: Glucoronidation and sulfonation: An activated conjugating molecule such as glucoronic acid, sulfate or glutathione etc. is combined with the drug to form a conjugated molecule. Type 2: Amino acid conjugation: An activated drug or substrate is conjugated with an amino acid such as glycine or glutamine.

Glutathione Conjugation:

Glutathione is a tripeptide found in most tissues, particularly in the liver. It performs important detoxification functions for all cells. The enzyme, glutathione S-transferase conjugates glutathione with drug intermediates to form a drug-glutathione conjugate. This conjugate can easily be excreted through bile or urine.

Amino acid Conjugation:

This is an important reaction in xenobiotic biotransformation; particularly for xenobiotics with carboxylic group or an aromatic hydroxylamine groups. Drug intermediates combine with glycine or glutamine to form an amino acid conjugate.