Sensitivity improvement for spectrofluorimetric determination of commonly used antifungal drug 'nystatin': application for oral suspension

In this paper, two simple, rapid and highly sensitive spectrofluorimetric methods were developed and validated for nystatin determination in its pure form and pharmaceutical dosage form (oral suspension). The first method was based on measuring the nystatin native fluorescence after dilution with isopropyl alcohol at 407 nm (excitation 303 nm). The fluoresence intensity was linearly dependant on the nystatin concentration within the specified range 50-500 ng ml(-1). The second was based on micellar enhancement of nystatin fluorescence using sodium dodecyl sulphate (SDS). In the presence of 2% w/v SDS, an similar to 1.9-fold enhancement could be achieved in the relative fluorescence intensity of nystatin. The linear range for the second method was 20-100 ng ml(-1). The limits of quantification and detection were found to be 43.23 ng ml(-1) and 14.27 ng ml(-1) (Method I), 6.08 ng ml(-1) and 2.0 ng ml(-1) (Method II). According to percentage recoveries and relative standard deviations (RSDs) obtained, the proposed methods were precise (RSDs were less than 2%), reproducible, and accurate and could be successfully applied for quantitative estimation of nystatin in its dosage form. The statistical results of this method were compared with that of the reported method and showed excellent agreement with respect to accuracy and precision.

Automated summary

Two simple, rapid, and highly sensitive spectrofluorimetric methods were developed for nystatin determination, showing linear relationship within specified concentration ranges. The methods were based on nystatin's native fluorescence and micellar enhancement with SDS, demonstrating good precision and reproducibility in quantitative estimation of nystatin in pharmaceutical dosage forms. The statistical comparison with reported methods showed excellent agreement in terms of accuracy and precision.