No abstract

High‐performance liquid chromatography was used in the development of a new simple method for the determination of spiramycin in urine and tablets. Experimental and instrumental conditions were first optimized for the separation of this compound and then the method was applied to real samples. The procedure was performed using an isocratic elution on ODB reversed phase C18 column (250 × 4.6 mm, 5 μm) with UV detection at 231 nm, and a very reasonable resolution was achieved. In urine, the developed method was employed after a simple and fast sample preparation involving pre‐column for clean‐up procedure, and using roxithromycin as internal standard. Linearity, in the range of 0.3–25 μg mL−1 showed a good linear correlation (R2 = 0.9994), with a detection limit down to 30 ng mL−1. In the following step, the quantification of spiramycin was studied in pharmaceutical forms. Results showed a good repeatability and the relative standard deviation was below to 2.18%. Precision was checked at three levels during three consecutive days with intra‐day and inter‐day coefficients of relative standard deviation not exceeding the value of 4.98%. The extraction recovery presented good results with values ranging from 90.12–101.13% for both matrixes.

A simple, rapid and validated high-performance liquid chromatographic method has been developed for the simultaneous determination of tretinoin and erythromycin in bulk and topical gel form. The analysis was achieved under isocratic mode with a specific reversed stationary phase and, using an eluent composed of acetonitrile/2methyl-2-propanol/hydrogen phosphate buffer of pH 7.0, delivered at a flow-rate of 1.0 mL min −1 , with UV detection at 215 nm. The procedure was validated for specificity, linearity, precision, accuracy and robustness. The calibration plots were linear over the concentration ranges of: 0.002-4.8 and 0.025-30 μg mL −1 , with lower detection limits of 0.007 and 0.0008 μg mL −1 for erythromycin and tretinoin, respectively. The developed method was applied for the simultaneous quantitative determination of both drugs in their marketed alcoholic gel formulation. Results of the mean percentage recoveries were in the range of 99.5-100.8%. K E Y W O R D Serythromycin, simultaneous quantification, topical gel, tretinoin