A 38-year-old man from rural Maharashtra presents with hypopigmented macules on the face and trunk with loss of sensation. Slit-skin smear is positive for acid-fast bacilli (AFB). He is started on WHO multidrug therapy (MDT) for lepromatous leprosy. Regarding the adverse effects and drug interactions of antileprotic agents used in his regimen, all of the following are true EXCEPT:

Explanation

## Adverse Effects and Drug Interactions of Antileprotic Drugs ### Correct Statements **High-Yield:** Rifampicin is a potent inducer of the cytochrome P450 system (especially CYP3A4), leading to increased metabolism and reduced plasma concentrations of oral contraceptives, warfarin, and many other drugs. This is a critical counseling point for female patients [cite:KD Tripathi 8e Ch 50]. **Key Point:** Dapsone causes dose-dependent hemolytic anemia and is contraindicated or requires careful monitoring in patients with G6PD deficiency. Baseline G6PD testing is mandatory before initiating dapsone therapy [cite:Harrison 21e Ch 207]. **Clinical Pearl:** Rifampicin causes harmless orange-red discoloration of urine, tears, sweat, and saliva due to its lipophilic nature and hepatic metabolism. Patients must be counseled that this is benign and reversible upon drug discontinuation [cite:Park 26e Ch 6]. ### The Incorrect Statement **Key Point:** Clofazimine is **NOT hepatotoxic** and does **NOT require routine liver function monitoring**. Unlike rifampicin (which can cause hepatotoxicity, especially in patients with pre-existing liver disease), clofazimine's primary adverse effects are gastrointestinal (abdominal pain, diarrhea) and dermatologic (pigmentation). Hepatotoxicity is not a recognized adverse effect of clofazimine. ### Adverse Effect Profile Comparison | Drug | Hemolytic Anemia | Hepatotoxicity | GI Upset | Pigmentation | Drug Interactions | | --- | --- | --- | --- | --- | --- | | Rifampicin | Rare | Yes (monitor LFTs) | Mild | Orange discoloration | **Strong CYP450 inducer** | | Dapsone | **Yes (G6PD risk)** | No | Mild | No | Minimal | | Clofazimine | No | **No** | **Yes (common)** | Red-brown (slow onset) | Minimal | | Ofloxacin | No | No | Mild | No | Minimal | **Mnemonic:** **DAFT** = Dapsone (hemolytic Anemia, G6PD risk), Rifampicin (Fibrosis/hepatotoxicity, CYP450 induction), Clofazimine (GI upset, pigmentation) — but Clofazimine is **NOT** hepatotoxic. ### Clinical Counseling Points 1. Screen for G6PD deficiency before dapsone initiation 2. Counsel female patients on rifampicin's contraceptive interaction 3. Reassure patients about benign rifampicin-induced discoloration 4. Monitor for clofazimine-induced GI symptoms (common, usually tolerable) 5. Monitor LFTs in patients with baseline liver disease on rifampicin