Original Articles
Sarita Kumari Yadav and Brahme
Abstract
Combination of antibiotics is generally preferred for the treatment of chronic infections by covering broad range of microbes. In this study we have evaluated to explore the feasibility of combination of ornidazole (OZ) and doxycycline (DX) to be administered together in a formulation. The compatibility between both drugs was studied by Infra-red spectroscopic study. Further, two UV method was developed and validated for simultaneous estimation of OZ and DX when present in combined dosage form. UV method is economical, less time consuming and can be used for routine analysis over HPLC method. The UV method included Verodt’s method (Method I) and Q-analysis method (Method II). Method I involve solving of simultaneous equations for obtained absorbances at the λmax of both the drugs i.e. 319 nm and 274 nm for OZ and DX respectively in phosphate buffer pH 6.8. Method II is based on measurement of absorbance at iso-absorptive point of both the drugs (292 nm) and λmax of OZ (319nm). The linearity was observed in the concentration range of 5-25μg/ml (R2>0.999) for OZ and 5-30μg/ml (R2>0.999) for DX at all the selected wavelengths. Both methods were compared for accuracy and precision for inter-day and intra-day variability. Limit of detection (LOD) and limit of quantitation (LOQ) were also determined to evaluate the sensitivity of the method. The method was validated and found to comply with ICH guidelines. Developed proposed method was successfully applied for the simultaneous estimation of OZ and DX when combined in synthetic mixture for routine analysis.