The colorimetric analysis of anti-tuberculosis fixed-dose combination tablets and capsules.
METHODS
The perceived need to demonstrate whether or not the actual amounts of rifampicin, isoniazid and pyrazinamide in fixed-dose combination tablets or capsules correspond to their stated drug contents.


OBJECTIVE
To adapt specific, robust and simple colorimetric methods that have been previously applied to measuring plasma and urinary rifampicin, isoniazid, pyrazinamide and ethambutol concentrations to estimate tablet and capsule drug contents.


METHODS
The methods were applied to the analysis of 14 commercially manufactured fixed-dose combinations: two capsule and three tablet formulations containing rifampicin and isoniazid; seven tablet formulations containing rifampicin, isoniazid and pyrazinamide; and two tablet formulations containing rifampicin, isoniazid, pyrazinamide and ethambutol.


RESULTS
All the combined formulations contained near to their stated drug contents. Replicate analyses confirmed the excellent precision of the drug analyses.


CONCLUSIONS
Such methods are not only rapid to perform but should be practical in many Third World situations with relatively modest laboratory facilities.
Ellard
G A
GA
Department of Medical Microbiology, St. George's Hospital Medical School, London, UK.
D000995:Antitubercular Agents / Q000008:administration & dosage* / Q000032:analysis*; D002214:Capsules / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D003124:Colorimetry; D004338:Drug Combinations; D004977:Ethambutol / Q000032:analysis; D007538:Isoniazid / Q000032:analysis; D011718:Pyrazinamide / Q000032:analysis; D012293:Rifampin / Q000032:analysis; D013607:Tablets / Q000737:chemistry
D000995:Antitubercular Agents; D002214:Capsules; D004338:Drug Combinations; D013607:Tablets; D011718:Pyrazinamide; D004977:Ethambutol; D007538:Isoniazid; D012293:Rifampin