Ethambutol is indicated for the treatment of pulmonary tuberculosis. It should not be used as the sole antituberculous drug, but should be used in conjunction with at least one other antituberculous drug. Selection of the companion drug should be based on clinical experience, considerations of comparative safety, and appropriate in vitro susceptibility studies. In patients who have not received previous antituberculous therapy, ie, initial treatment, the most frequently used regimens have been the following:
Ethambutol plus isoniazid
Ethambutol plus isoniazid plus streptomycin.
In patients who have received previous antituberculous therapy, mycobacterial resistance to other drugs used in initial therapy is frequent. Consequently, in such retreatment patients, Ethambutol should be combined with at least one of the second line drugs not previously administered to the patient and to which bacterial susceptibility has been indicated by appropriate in vitro studies. Antituberculous drugs used with Ethambutol have included cycloserine, ethionamide, pyrazinamide, viomycin and other drugs. Isoniazid, aminosalicylic acid, and streptomycin have also been used in multiple drug regimens. Alternating drug regimens have also been utilized.
Should be taken with food.
Delayed or reduced absorption with aluminium hydroxide.
Ethambutol is contraindicated in patients who are known to be hypersensitive to this drug. It is also contraindicated in patients with known optic neuritis unless clinical judgment determines that it may be used. Ethambutol is contraindicated in patients who are unable to appreciate and report visual side effects or changes in vision
Retrobulbar neuritis with reduction in visual acuity, constriction of visual field, central or peripheral scotoma and green-red colour blindness of 1 or both eyes. Reduced renal clearance of urate and may precipitate acute gout. Confusion, disorientation, hallucinations, headache, dizziness, malaise, jaundice or transient liver dysfunction, peripheral neuropathy, thrombocytopenia, pulmonary infiltrates, eosinophilia and GI disturbances (e.g. nausea, vomiting, anorexia, abdominal pain). Rarely, retinal haemorrhage, hypersensitivity reactions including rashes, pruritus, leucopenia, fever, and joint pains.
Category C: Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.
Patient with ocular defects (e.g. cataracts, recurrent ocular inflammatory conditions, diabetic neuropathy). Renal impairment. Pregnancy and lactation.
