Quantitative estimation of isoniazid content in the commercially available and government-supplied formulations

Multi-drug resistant tuberculosis is on the rise, resulting in treatment failure. One potential reason for drug resistance is the substandard quality of manufactured antituberculous drugs. This study aims at finding out the difference in the quantity of isoniazid between government-supplied tablets and commercially available tablets.

Tablets from the single most commonly used brand of isoniazid manufactured by a pharmaceutical company and from RNTCP DOTS providing centre were obtained for the estimation of concentration using a spectrophotometer. The results were analysed using Un-paired Student's t-test.

Of the 98 isoniazid tablets from each arm studied, none had the strength that deviated from the WHO limit of 90-110%, i.e. 270-330 mg. The mean strength ±SD of the commercial preparation of isoniazid tablets was found to be 295.16 ± 12.14. The mean strength ± SD of DOTS isoniazid tablets was found to be 298.69 ± 9.55. The difference observed in the strengths of isoniazid tablets between DOTS and commercial preparation was statistically insignificant (p = 0.1704).

This method to estimate the strength of isoniazid tablets is inexpensive, relatively easy, and considerably accurate to perform, and hence can be employed in primary or secondary care centres to ensure the standard strengths of tablets dispensed from such centres.