The major CYP isoform responsible for the formation of 4-hydroxytamoxifen is:Question 22Answera.CYP3A4b.CYP2D6c.CYP1A2d.CYP2C19

Break Down the Problem

1. Identify the key components of the question: CYP isoforms, specifically focusing on the formation of 4-hydroxytamoxifen.
2. Determine which CYP isoform is primarily responsible for this process.

Relevant Concepts

• CYP Isoforms: These are enzymes in the cytochrome P450 family that play a significant role in drug metabolism.
• 4-hydroxytamoxifen: This is a metabolite of tamoxifen, an anti-estrogen drug used in the treatment of breast cancer.

Analysis and Detail

1. CYP3A4 - Involved in the metabolism of a variety of medications but not specifically noted for 4-hydroxytamoxifen formation.
2. CYP2D6 - Known to be a critical enzyme in the metabolism of tamoxifen into its active metabolites, including 4-hydroxytamoxifen.
3. CYP1A2 and CYP2C19 - While they play roles in drug metabolism, they are not the primary isoforms associated with tamoxifen metabolism.

Verify and Summarize

• Research supports that CYP2D6 is the main enzyme converting tamoxifen to its more active form, 4-hydroxytamoxifen.
• Based on literature, CYP2D6 is primarily implicated in this metabolic pathway.

Final Answer

The major CYP isoform responsible for the formation of 4-hydroxytamoxifen is b. CYP2D6.