Before starting an abacavir containing antiretroviral regimen, which pre-treatment screening test must be performed to prevent a potentially fatal idiosyncratic reaction?

• A G6PD level
• B HLA-B*15:02 typing
• C HLA-B*57:01 typing ✓
• D Baseline CD4 count below 200 cells/mm3

Explanation

Abacavir causes a multisystem hypersensitivity syndrome with fever, rash and constitutional symptoms that can be fatal on rechallenge. Risk is strongly associated with HLA-B*57:01, and prospective screening eliminates most cases, which is why guidelines mandate genotyping before initiation. HLA-B*15:02 predicts carbamazepine induced Stevens-Johnson syndrome, not abacavir hypersensitivity. G6PD relates to oxidative haemolysis from drugs like dapsone.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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