title: Evaluation of the recently reported USP gradient HPLC method for analysis of anti-tuberculosis drugs for its ability to resolve degradation products of rifampicin.
abstract: The recently notified USP gradient HPLC method for quantitative determination of rifampicin, isoniazid and pyrazinamide in fixed dose combination (FDC) formulations was evaluated to determine its ability to resolve major degradation products of rifampicin, viz. 3-formylrifamycin SV, rifampicin N-oxide, 25-desacetyl rifampicin, rifampicin quinone, and the newly reported isonicotinyl hydrazone, an interaction product of 3-formylrifamycin and isoniazid. The first observation was that the requirements of theoretical plates listed in the given method were met for rifampicin, but not for isoniazid and pyrazinamide, even on columns of different makes. The resolving power of the method was also dependent upon make of the column. On two of the three columns of the three tested, it was able to resolve most degradation products, except rifampicin N-oxide and 25-desacetylrifampicin, which were overlapping. The method was modified and an overall satisfactory resolution for all components was obtained by changing the buffer: organic modifier ratio of solution B in the gradient from 45:55 to 55:45 and decreasing the flow rate from 1.5 to 1.0 ml/min, keeping all other conditions constant.
authors.affiliation: Department of Pharmaceutical Analysis, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, SAS Nagar, Punjab 160 062, India.
authors.forename: Bhavika
authors.initials: B
authors.lastname: Mohan
authors.forename: Nishi
authors.initials: N
authors.lastname: Sharda
authors.forename: Saranjit
authors.initials: S
authors.lastname: Singh
mesh_terms: D000904:Antibiotics, Antitubercular / Q000032:analysis*; D000995:Antitubercular Agents / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D004338:Drug Combinations; D004977:Ethambutol / Q000032:analysis; D007538:Isoniazid / Q000032:analysis; D010602:Pharmacopoeias as Topic; D011718:Pyrazinamide / Q000032:analysis; D012015:Reference Standards; D012293:Rifampin / Q000031:analogs & derivatives / Q000032:analysis*; D013607:Tablets; D014481:United States
chemical_list: D000904:Antibiotics, Antitubercular; D000995:Antitubercular Agents; D004338:Drug Combinations; D013607:Tablets; D011718:Pyrazinamide; D004977:Ethambutol; D007538:Isoniazid; D012293:Rifampin