Voltammetric determination of josamycin (a macrolide antibiotic) in dosage forms and spiked human urine.

Abstract The voltammetric behaviour of josamycin (a macrolide antibiotic) has been studied using direct current (DC t ) alternating current (AC t ) and differential pulse polarography (DPP). In Britton–Robinson buffers, josamycin developed cathodic waves over the pH range 7–12. At pH 10, a well-defined cathodic wave with diffusion current constant of 1.06±0.19 ( n =5) was obtained. The wave was characterized as being diffusion-controlled; and partially affected by adsorption phenomenon. The current-concentrations plots are rectilinear over the range 10–60 and 6–50 μg/ml using DC t mode and DPP mode, respectively. The minimum detectability limit was 1.2 μg/ml (1.9×10 −6 M) adopting the DPP mode. A method was proposed for the determination of josamycin in its tablets adopting both DC t and DPP modes. The results obtained were in good agreement with those given by the manufacturer. The method was extended to the in-vitro determination of the drug in spiked human urine; the % recovery was 98.06±1.76% ( n =5). The number of electrons involved in the reduction process was accomplished and a proposal of the electrode reaction was presented.