Author(s): Laserson KF, Kenyon AS, Kenyon TA, Layloff T, Binkin NJ
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Abstract SETTING: The prevalence of substandard anti-tuberculosis drugs is unknown. To maximize the effectiveness of tuberculosis (TB) control efforts, simple, inexpensive drug quality screening methods are needed. DESIGN: Isoniazid (INH) and rifampin (RMP) single- and fixed-dose combination (FDC) formulations were collected from selected TB programs and pharmacies in Colombia, Estonia, India, Latvia, Russia and Vietnam. Samples were screened using a recently developed thin-layer chromatography (TLC) kit. All abnormal samples and a 40\% random sample of normal formulations were further analyzed using confirmatory techniques. Samples outside of 85\% to 115\% of stated content, and/or containing compounds other than the stated drug, were defined as being substandard. RESULTS: Overall, 10\% (4/40) of all samples, including 13\% (4/30) RMP samples, contained <85\% of stated content. More FDCs (5/24, 21\%) than single-drug samples (2/16, 13\%) were substandard. A comparison of TLC with the confirmatory analysis for RMP analysis showed a sensitivity of 100\% (4/4), a specificity of 92\% (24/26), a positive predictive value (PPV) of 67\% (4/6), and a negative predictive value (NPV) of 100\% (24/24). An analysis of INH showed a specificity of 90\% (9/10). However, sensitivity, PPV, and NVP could not be determined. CONCLUSION: A substantial number of anti-tuberculosis drugs from several countries, in particular FDCs, were found to be substandard. Such drugs may contribute to the creation of drug-resistant TB. TLC is an effective, convenient, and inexpensive method for the detection of substandard drugs.
This article was published in Int J Tuberc Lung Dis
and referenced in Journal of Bioequivalence & Bioavailability