Isoniazid induced neuropathy in slow versus rapid acetylators: an electrophysiological study.

Clinical, biochemical and nerve conduction studies were performed in 100 cases of tuberculosis taking isonicotinic acid hydrozide (isoniazid) for more than 12 weeks. Electro-physiological studies were carried out in a similar number of normal age and sex matched controls. In 16 percent of cases an abnormality was documented in the motor nerve conduction velocity, amplitude and terminal latency of the common peroneal, ulnar and median nerves; of these, only two patients had objective evidence of neuritis. The occurrence of isoniazid neuropathy was found to be more in the fourth decade of life (10 of 16), in those who had taken the drug for over six months (13 of 16), and in 'slow' inactivators (10 of 16).