THE PREVENTION AND TREATMENT OF ISONIAZID TOXICITY IN THE THERAPY OF PULMONARY TUBERCULOSIS. 2. AN ASSESSMENT OF THE PROPHYLACTIC EFFECT OF PYRIDOXINE IN LOW DOSAGE.

A recent report from the Tuberculosis Chemotherapy Centre, Madras, showed that a vitamin-B-complex preparation containing a small amount of pyridoxine (as well as aneurine hydrochloride, riboflavine, nicotinamide, panthenol and cyanocobalamin) was effective in the treatment of peripheral neuropathy caused by daily high-dosage (12.5-15.2 mg/kg body-weight) isoniazid therapy of pulmonary tuberculosis. The present report gives results which show that the B-complex preparation is fully effective in preventing peripheral neuropathy in patients receiving the same high dosage of isoniazid, and that this is due to the small pyridoxine content of only 6 mg daily, and not to any of its other constituents. The low cost of this small dose of pyridoxine makes high-dosage isoniazid therapy, given in combination with other drugs or alone, a possible proposition in developing countries.Studies in the Centre have produced clear evidence that there is an increase in the frequency of peripheral neuropathy when the dosage of isoniazid is increased from 7.8-9.6 mg/kg body-weight to 12.5-15.6 mg/kg daily, and that its incidence is higher among slow than among rapid inactivators of isoniazid.The studies also show that increasing the dosage of isoniazid when given alone from a moderate daily dosage of 7.8-9.6 mg/kg to the high daily dosage of 12.5-15.6 mg/kg has not materially altered the radiographic or the bacteriological response to treatment.