The geographic distribution of tuberculosis and pyridoxine supply in Ontario

Acute poisoning with isoniazid causes generalized convulsions which should be treated with intravenous pyridoxine and a rapidly-acting anticonvulsant. The purpose of this study was to determine the correlation between the distribution of tuberculosis (as a proxy for isoniazid use) and acute care hospital supplies of intravenous pyridoxine (the antidote for isoniazid overdose). The distribution of tuberculosis was based on Ontario public health regions. The study was descriptive using simple linear regression to assess the degree of correlation. Only 15.6% of Ontario acute care hospitals have enough intravenous pyridoxine to treat an average isoniazid overdose. The distribution of tuberculosis and the number of hospitals in the region correlated best with hospital supplies of pyridoxine, although these variables explained only 22% and 23.7%, respectively, of the variation in supply. It does not appear that the distribution of tuberculosis is a major determinant of the availability of the isoniazid antidote, pyridoxine. Acute care hospitals in Ontario should re-evaluate their need for pyridoxine in light of the incidence of tuberculosis in their regions. Each hospital should stock at least 5 Gm of intravenous pyridoxine; additional amounts may be appropriate if there is an increased incidence in the area.