Ethambutol in the Initial Treatment of Pulmonary Tuberculosis

In 4 U. S. Public Health Service trials, ethambutol was tested in doses of 6 and 15 mg per kg as a substitute for p-aminosalicyclic acid in 1,449 patients and as a substitute for pyrazinamide in 326 patients; 1,052 patients treated with nonethambutol regimens served as control subjects. Ethambutol in doses of 15 mg per kg was therapeutically an effective substitute for either p-aminosalicyclic acid or pyrazinamide and was virtually nontoxic. the frequency and degree of changes in visual acuity were equal with ethambutol and nonethambutol regimens.