## Adverse Effects and Drug Interactions of Antileprotic Drugs ### Correct Statements (Options 0, 1, 3) **Option 0 — Rifampicin Enzyme Induction:** **Key Point:** Rifampicin is a potent inducer of hepatic cytochrome P450 enzymes (especially CYP3A4, CYP2C9). This increases the metabolism of many drugs, reducing their plasma concentrations and therapeutic efficacy. **Clinical Pearl:** Oral contraceptives and warfarin are particularly affected — women on OCP should use alternative contraception; INR monitoring is essential in patients on warfarin. **Option 1 — Dapsone Hemolytic Anemia:** **Key Point:** Dapsone causes dose-dependent hemolytic anemia by oxidizing hemoglobin to methemoglobin. Patients with G6PD deficiency are at severe risk of acute hemolytic crisis. **High-Yield:** Baseline G6PD screening is mandatory before starting dapsone. Regular monitoring of hemoglobin and reticulocyte count is required during therapy. **Option 3 — Rifampicin Hepatotoxicity:** **Key Point:** Rifampicin is hepatotoxic and can cause elevated transaminases, cholestasis, and rarely fulminant hepatic failure. Baseline liver function tests (LFTs) and periodic monitoring are essential, especially in patients with pre-existing liver disease, alcoholism, or hepatitis. ### Incorrect Statement (Option 2) — The Answer **Option 2 — Clofazimine Skin Discoloration:** **Warning:** This is FALSE regarding the timeline of reversibility. Clofazimine causes red-brown to black discoloration of skin, nails, and body fluids (including sweat, tears, and urine). This discoloration is NOT reversible within weeks — it persists for months to years (often 6–12 months or longer) after drug discontinuation because clofazimine is lipophilic and accumulates in fatty tissues. **Clinical Pearl:** Patients must be counseled about this cosmetically distressing but benign side effect. The slow reversal is a major cause of poor adherence, especially in women. ### Adverse Effect Comparison Table | Drug | Major Adverse Effect | Mechanism | Monitoring/Prevention | |---|---|---|---| | Rifampicin | Hepatotoxicity, enzyme induction | CYP450 induction; direct hepatotoxicity | Baseline & periodic LFTs; drug interaction check | | Dapsone | Hemolytic anemia, methemoglobinemia | Oxidation of Hb; G6PD deficiency risk | Baseline G6PD; CBC monitoring | | Clofazimine | Skin discoloration (red-brown to black) | Lipophilic accumulation in fat | Patient counseling; discoloration reverses slowly (6–12 months+) | **Mnemonic: DRAC** — Dapsone (hemolytic), Rifampicin (hepatotoxicity), Antileprotics (drug interactions), Clofazimine (cosmetic discoloration).
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