18.02.3 Ethambutol

Ethambutol is only active against Mycobacteria, not other bacteria. Ethambutol is bacteriostatic, not bacteriocidal. The mechanism of action of ethambutol that underlies this bacteriostatic effect is unclear.

The most serious adverse effect with ethambutol is optic neuritis (inflammation of the optic nerve). This neuritis may lead to blindness. Fortunately the neuritis is usually reversed by stopping the treatment with ethambutol. Ethambutol, also impairs the renal clearance of uric acid, and this can lead to hyperuricaemia and gout.