Phase II biotransformation of xenobiotics involves:

• A CYP450-mediated oxidation, reduction, or hydrolysis of the drug
• B Conjugation reactions (glucuronidation, sulfation, acetylation, glutathione conjugation) to increase water solubility ✓
• C Active tubular secretion in the kidney
• D P-glycoprotein-mediated efflux from intestinal cells

Explanation

Phase I reactions (CYP450) introduce or unmask functional groups; Phase II reactions conjugate these groups with polar moieties (glucuronic acid via UGT, sulfate via SULT, acetyl group via NAT, glutathione via GST, or glycine) to create water-soluble products excreted in urine or bile. P-glycoprotein and renal secretion are elimination mechanisms, not biotransformation. Phase I is oxidation/reduction/hydrolysis.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

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