CLOFAZIMINE TABLETS 100 MG

Indications

• Leprosy (Hansen's disease)

Mechanism of action

Clofazimine's precise mechanism of action is not completely understood, but it is thought to exert its antimicrobial effects by interacting with bacterial membrane phospholipids, generating antimicrobial lysophospholipids. This action destabilizes the bacterial membrane, affecting ion uptake and ATP production. Additionally, clofazimine has anti-inflammatory effects through the inhibition of T-lymphocyte activation and proliferation, possibly by antagonizing T-cell Kv 1.3 potassium channels and promoting the release of E-series prostaglandins and reactive oxygen species from surrounding immune cells.

Pharmacodynamics

Clofazimine exhibits a slow bactericidal effect specifically against Mycobacterium leprae due to its action on the bacterial outer membrane and possibly affecting the respiratory chain and ion transporters. It has anti-inflammatory properties that suppress T-lymphocyte activity. The drug is known for causing significant skin discoloration in approximately 75-100% of patients, with discoloration potentially lasting months to years post-treatment. Clofazimine can also lead to gastrointestinal complications, including abdominal obstruction due to drug crystallization in the intestinal mucosa.

Pharmacokinetics

Clofazimine is highly lipophilic, leading to extensive tissue binding and a long half-life, which contributes to its prolonged action. It is primarily excreted in the feces, with minimal renal excretion. The time to peak plasma concentration occurs several hours after administration, and it is administered daily despite its long duration of action. The drug's pharmacokinetics can be affected by hepatic function, necessitating caution in patients with liver impairment.

Contra-indications

• Hypersensitivity to clofazimine or any of its components
• Severe hepatic dysfunction

Adverse effects

• Skin discoloration (orange-pink to brownish-black)
• Abdominal obstruction
• Nausea
• Vomiting
• Diarrhea
• Fatigue
• Abdominal pain

Interactions

• Bedaquiline: Unknown (increases risk of QT-prolongation)

Precautions

• Use with caution in patients with hepatic dysfunction
• Monitor for signs of abdominal obstruction
• Skin discoloration may take months to years to reverse after therapy cessation

Pregnancy

Clofazimine is classified as pregnancy category C. Its use during pregnancy should be carefully considered, weighing the benefits against potential risks.

Breast-feeding

Clofazimine may pass into breast milk. Caution should be exercised when administering to nursing mothers.

Storage

Store at room temperature, away from moisture and heat. Keep out of reach of children.

Formulations

• Capsule: 50 mg
• Capsule: 100 mg
• Oral suspension: 100 mg/5 ml

Mechanism of action

Although the precise mechanism(s) of action of clofazimine have not been elucidated, its antimicrobial activity appears to be membrane-directed. It was previously thought that, due to its lipophilicity, clofazimine participated in the generation of intracellular reactive oxygen species (ROS) via redox cycling, specifically H₂O₂ and superoxide, which then exerted an antimicrobial effect. A more recent and compelling theory involves clofazimine interacting with bacterial membrane phospholipids to generate antimicrobial lysophospholipids - bactericidal efficacy may, then, arise from the combined membrane-destabilizing effects of both clofazimine and lysophospholipids, which interfere with K+ uptake and, ultimately, ATP production. The anti-inflammatory activity of clofazimine is the result of its inhibition of T-lymphocyte activation and proliferation. Several mechanisms have been proposed, including direct antagonism of T-cell Kv 1.3 potassium channels and indirect action by promoting the release of E-series prostaglandins and reactive oxygen species from bystander neutrophils and monocytes.

Pharmacodynamics

Clofazimine exerts a slow bactericidal effect on <i>Mycobacterium leprae</i> (Hansen's bacillus) due primarily to its action on the bacterial outer membrane, though there is some evidence that activity on the bacterial respiratory chain and ion transporters may play a role. It also exerts anti-inflammatory properties due to the suppression of T-lymphocyte activity. Clofazimine has a relatively long duration of action owing to its long residence time in the body, but is still administered daily. Approximately 75-100% of patients receiving clofazimine will experience an orange-pink to brownish-black discoloration of the skin, conjunctivae, and bodily fluids. Skin discoloration may take several months or years to reverse following the cessation of therapy. Clofazimine has also been implicated in abdominal obstruction, in some cases fatal, due to the deposition of drug and formation of crystals in the intestinal mucosa - complaints of abdominal pain and nausea/vomiting should be investigated promptly, and the doses of clofazimine should be lowered or discontinued if it is found to be the culprit. Its use should be avoided in patients with hepatic dysfunction.