Ethambutol in the Retreatment of Pulmonary Tuberculosis

Abstract

(1) EMB was used in the retreatment of drug resistant pulmonary tuberculosis from May, 1962 to July, 1964. The first year EMB was given in a continuous dose of 25 mg./kg. and after May, 1963 the dose was 25 mg./kg. for 60 days and 15 mg./kg. thereafter. (2) Sixty-four patients were treated with (a) EMB (17 patients), (b) EMB combined with one other antituberculosis drug not previously used in that group (47 patients). The 47 received EMB-CS (three), EMB-VIO (eight) and EMB-PZA (36). All patients continued to receive INH. (3) EMB alone causes early clinical, bacteriologic and roentgenographic improvement but these benefits may not be of permanent nature. EMB alone is of value for short term care in acute exacerbations or complications of tuberculosis and for pre- and postoperative surgical coverage. (4) With EMB combined drug regimens (a) clinical improvement was rapid, marked and was maintained; (b) 75 per cent of patients with four months' or more treatment had reversal of infectiousness. There have thus far been two instances of bacteriologic relapse while under treatment; (c) some roentgenographic improvement occurred in 55 per cent of the cases. Cavity closure occurred in four cases and open negative healing in five others. There has been no instance of roentgenographic worsening; (d) two patients on continuous doses of 25 mg./kg. of EMB developed visual disturbances and decrease of vision in the seventh and ninth month of treatment respectively with complete return of vision after discontinuation of EMB; (e) there has thus far been no case of eye toxicity with the dose of EMB of 25 mg./kg. for 60 days and 15 mg./kg. thereafter; (f) there has been no other evidence of toxicity, side effects or intolerance to EMB and there has been excellent patient acceptability of EMB; (g) in six patients drugs initiated with EMB were discontinued (VIO in one case for 8th nerve toxicity and PZA in five for increased transaminase levels). (5) EMB combined drug regimens are useful for short term purposes (acute exacerbations of tuberculosis, pre- and post-operative surgical coverage) and for long term chemotherapeutic management of the retreatment chronic infectious resistant case.