SENSITIVE AND SELECTIVE SPECTROPHOTOMETRIC DETERMINATION OF SPIRAMYCIN IN PURE FORM AND IN PHARMACEUTICAL FORMULATIONS

Three simple and sensitive and reproducible spectrophotometric methods were developed for the determination of spiramycin (SPM) in pure form and in pharmaceutical formulations (tablets). The first and second methods, A and B, are based on the formation of charge transfer complex between drug and the chromogenic reagents quinalizarin (method A) and alizarin red S (method B) producing charge transfer complexes in methanolic medium which showed an absorption maximum at 568 and 527 nm using methods A and B, respectively. Beer’s law was obeyed in the concentration range of 1.0–10 and 2.0-18 μg mL^-1 with mean percentages accuracy of 100.39±0.89 and 100.26±0.60 using methods A and B, respectively. The third method C, is based on the reduction of Fe(III) by spiramycin in acid medium and subsequent interaction of Fe(II) with ferricyanide to form Prussian blue, which exhibits an absorption maximum at 760 nm. Beer’s law was obeyed in the concentration range of 2.0–12 μg mL^-1 with mean percentage accuracy of 99.85±0.956. All variables were studied to optimize the reaction conditions for each method. The molar absorptivity, Sandell sensitivity, detection and quantitation limits were calculated. Statistical treatment of the results reflects that the proposed methods are precise, accurate and easily applied for the determination of spiramycin in pure form and in tablets and the results were statistically compared with that reported method.