Peripheral neuritis due to isoniazid.

It is well known that in the treatment of tuberculosis with isoniazid the complication of peripheral neuritis may arise. This complication is normally rare when small dosages of the drug are used, but a high incidence of the neuropathy has recently been observed in East Africa in a group of malnourished tuberculous patients receiving isoniazid in comparatively low dosage (4-6 mg/kg body-weight daily). The present paper reports on 20 cases of peripheral neuritis encountered in Madras, India, among 338 poorly nourished tuberculous patients during a trial of four isoniazid regimens, two of low and two of high dosage (3.9-5.5 and 7.8-9.6 mg/kg body-weight daily, respectively). Nineteen of the 20 cases occurred in the two groups of patients receiving the high dosage and these 19 patients were found to have a higher mean serum level of free isoniazid than the patients in the same groups who did not develop the complication. The authors consider that dosages of 7.8-9.6 mg/kg body-weight daily should not be used for the mass therapy of poorly nourished patients unless steps are taken to prevent the development of peripheral neuritis. Pyridoxine has been reported to be an effective preventive, but is too expensive for use on a large scale. This study indicates, however, that administration of the cheaper vitamin B complex might give satisfactory results and warrants further investigation.