Related Experiment Video
Updated: Jul 28, 2026

The MODS method for diagnosis of tuberculosis and multidrug resistant tuberculosis
Published on: August 11, 2008
Substandard tuberculosis drugs on the global market and their simple detection
K F Laserson1, A S Kenyon, T A Kenyon
1Division of TB Elimination, National Centers for HIV/AIDS, STD and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA. kel4@cdc.gov
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.
Related Concept Videos
Pulmonary Tuberculosis I
Causative Organism
The primary infectious agent causing tuberculosis is Mycobacterium tuberculosis, a slow-growing, acid-fast, aerobic rod that exhibits sensitivity to heat and ultraviolet light. Instances of Mycobacterium bovis and Mycobacterium avium contributing to the development of TB infection are rare.
Mode of...
Pulmonary Tuberculosis III
The first classification is based on the development of the disease, and it includes the following categories:
Pulmonary Tuberculosis IV
Several diagnostic approaches are used to detect TB. The conventional method is the Tuberculin Skin Test (TST), also known as the Mantoux test. However, this method has...
Pulmonary Tuberculosis V
Latent tuberculosis infection occurs when TB bacteria are present in a person's body, but are not causing illness or symptoms. It is not contagious, and preventive treatment is crucial to avoid the progression...
Automated Microbial Diagnostics
Tuberculosis

