Clofazimine

Clofazimine is a lipophilic antimicrobial agent of the phenazine dye class, used primarily to treat leprosy (Mycobacterium leprae). It forms part of multidrug therapy for multibacillary leprosy and is also employed to prevent or treat inflammatory episodes such as erythema nodosum leprosum (ENL). The drug is produced by Streptomyces species and is available under brand names such as Lamprene.

The exact mechanism of action is not fully understood. Clofazimine exhibits activity against Mycobacterium leprae and is thought to intercalate into bacterial DNA and disrupt replication, while also exerting anti-inflammatory effects that help control ENL by modulating immune responses.

Pharmacokinetically, clofazimine is highly lipophilic and tends to accumulate in adipose tissue and the skin, resulting in a very long tissue half-life and persistent drug effects after discontinuation. It is administered orally, with hepatic metabolism and primary excretion in feces. Its tissue accumulation explains the characteristic, long-lasting side effects.

In leprosy treatment, clofazimine is given as part of MDT: commonly 50 mg daily with a 300 mg supervised monthly dose, continued for the duration of multidrug therapy for multibacillary disease. Higher doses have been used to control ENL flares in some cases.

The most notable adverse effect is a reddish-brown to mahogany skin discoloration, which can be persistent. Other common effects include photosensitivity, gastrointestinal symptoms, and potential hepatotoxicity. Patients should be monitored for liver function, and therapy should be used with caution in individuals with hepatic impairment. Safety in pregnancy is not well established.