Ethambutol (E)

Ethambutol is selectively tuberculostatic. The fast multiplying bacilli are more susceptible to the drug. When added to the triple-drug regimen of RHZ, it hastens the rate of the sputum conversion and prevents the development of resistance.

Indication.

• Tuberculosis in conjunction with other anti-tuberculous drugs.

Mechanism of action.

• Inhibits arabinose transferases involved in arabinogalactan synthesis, interfering with mycolic acid incorporation in the mycobacterial cell wall.

Resistance.

• Mutation of the embB gene reduces the target enzyme’s affinity for Ethambutol.
• No cross-resistance with any other antitubercular drug has been reported.

Contraindications.

• Patients with renal disease.
• Patients with optical neuritis.
• Used with due precaution in children.

Adverse effects.

• Loss of visual acuity due to optical neuritis- dose-related toxicity.
• Nausea, fever, rashes, and rarely peripheral neuritis.

Hyperuricemia

• due to interference with urate excretion in the body.

Dosage.

• MYCOBUTOL, MYAMBUTOL, COMBUTOL 0.2, 0.4, 0.6, 0.8,1.0 g tablets.