The colorimetric analysis of anti-tuberculosis fixed-dose combination tablets and capsules

Area of Science:

• Pharmaceutical analysis
• Analytical chemistry
• Tuberculosis drug quality control

Background:

• Ensuring the correct dosage of antituberculosis drugs in fixed-dose combinations (FDCs) is critical for treatment efficacy.
• Existing analytical methods for drug content determination may be complex or require specialized equipment, limiting their use in resource-limited settings.

Purpose of the Study:

• To adapt and validate simple, robust colorimetric methods for quantifying rifampicin, isoniazid, pyrazinamide, and ethambutol in FDCs.
• To assess the accuracy and precision of these methods for estimating drug contents in tablets and capsules.

Main Methods:

• Colorimetric methods, previously used for plasma and urine analysis, were adapted for pharmaceutical formulations.
• Fourteen commercially available FDCs containing combinations of rifampicin, isoniazid, pyrazinamide, and ethambutol were analyzed.

Main Results:

• All analyzed FDCs demonstrated drug contents close to their stated amounts.
• Replicate analyses confirmed the high precision of the colorimetric drug assays.

Conclusions:

• Adapted colorimetric methods provide a rapid and practical approach for assessing drug content in FDCs.
• These methods are suitable for quality control in settings with modest laboratory facilities, particularly in developing countries.