## Clofazimine: Mechanism and Clinical Features **Key Point:** Clofazimine is a lipophilic riminophenazine that intercalates into mycobacterial DNA, generates reactive oxygen species (ROS), and causes distinctive red-brown pigmentation of skin and body fluids due to its lipophilic nature and deposition in fatty tissues. ### Mechanism of Action 1. **DNA Intercalation:** Clofazimine intercalates into the double helix of mycobacterial DNA 2. **ROS Generation:** Produces reactive oxygen species that damage mycobacterial cell structures 3. **Bacteriostatic Activity:** Inhibits growth of *Mycobacterium leprae* and *Mycobacterium avium* complex ### Distinctive Pharmacological Features | Feature | Details | | --- | --- | | **Onset** | Very slow (2–8 weeks for clinical improvement) | | **Lipophilicity** | Highly lipophilic; accumulates in fatty tissues | | **Pigmentation** | Red-brown discoloration of skin, conjunctiva, sclera, and body fluids (urine, sweat, tears) | | **Half-life** | Extremely long (70 days); slow elimination | | **Metabolism** | Minimal hepatic metabolism; fecal excretion | **High-Yield:** Clofazimine is the ONLY antileprotic that causes red-brown discoloration — this is a pathognomonic clinical sign and a high-yield exam feature. ### Clinical Use - Used in lepromatous and borderline lepromatous leprosy as part of MDT - Particularly valuable in dapsone-resistant cases - Also active against *M. avium* complex in HIV patients **Mnemonic:** **CLOF** = **C**olor change (red-brown), **L**ipophilic, **O**xidative stress (ROS), **F**ast intercalation into DNA **Clinical Pearl:** The slow onset of action and prolonged half-life mean clofazimine must be continued for 12 months after completion of other MDT agents to prevent relapse. Patients must be counseled about the cosmetic discoloration, which can persist for months after discontinuation.
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