Development of Validated Chromatographic Methods for the Simultaneous Determination of Metronidazole and Spiramycin in Tablets

Two chromatographic methods have been described for the simultaneous determination of metronidazole (MET) and spiramycin (SPY) in their mixtures. The first method was based on a high performance thin layer chromatographic (HPTLC) separation of the two drugs followed by densitometric measurements of their spots at 240 nm. The separation was carried out on Merck TLC aluminum sheets of silica gel 60 F 254 using methanol: chloroform (9:1, v/v ) as a mobile phase. Analysis data was used for the linear regression line in the range of 1.0–2.0 and 0.8–2.0 μg band −1 for MET and SPY, respectively. The second method was based on a reversed-phase liquid chromatographic separation of the cited drugs on a C-18 column (5 μm, 250 × 4.6 mm, i.d.). The mobile phase consisted of a mixture of phosphate buffer of pH 2.4 and acetonitrile (70:30, v/v ). The separation was carried out at ambient temperature with a flow rate of 1.0 mL min −1 . Quantitation was achieved with UV detection at 232 nm based on peak area with linear calibration curves at concentration ranges 0.4–50.0 and 0.5–50.0 μg mL −1 for MET and SPY, respectively. The proposed chromatographic methods were successfully applied to the determination of the investigated drugs in pharmaceutical preparations. Both methods were validated in compliance with ICH guidelines; in terms of linearity, accuracy, precision, robustness, limits of detection and quantitation and other aspects of analytical validation.