The first spectrofluorimetric approach for quantification of colistin sulfate and its prodrug colistimethate sodium in pharmaceutical dosage form and human plasma

Abstract

A new, accurate, nonextractive, and sensitive fluorimetric approach was proposed and validated for the first time estimation of colistin sulfate and its inactive prodrug colistimethate sodium in its bulk form, pharmaceutical formulations, and human plasma. The approach relied on condensation between acetylacetone/formaldehyde and the primary amino moiety of nonfluorescent colistin in Teorell and Stenhagen buffer (pH 2.8) by the Hantzsch reaction to form a highly fluorescent dihydropyridine derivative. The fluorescent product was measured at 460 nm (λex = 402 nm). A plot of relative fluorescence intensity (RFI) versus concentration was rectilinear over the range 200–4000 ng ml−1 with excellent correlation (r) and determination (r2) coefficients of 0.9999 and 0.9998, respectively. The limit of detection (LOD) and limit of quantitation (LOQ) were 40.91 and 123.99 ng ml−1, respectively. The present procedure was useful for determination of colistin sulfate either in powder form for suspension or in its parenteral prodrug colistimethate sodium in vial formulation. The investigated approach was applied for in vitro quantification of this drug in spiked human plasma, with a per cent mean recovery of 98.24 ± 1.34. The proposed method is reliable, selective, and does not require tedious sample pretreatment steps, expensive instrumentation, or harmful reagents, all of which make it ideally suited for use in quality control laboratories.

Salvage parenteral antibiotics for multidrug‐resistant (MDR) Gram‐negative bacteria; a fluorescamine‐based technique for ultrasensitive spectrofluorimetric measurement of Polymyxins; human plasma application

“…The proposed method could be considered as ultrasensitive compared with the previously reported spectrophotometric, [ 9,11,12 ] spectrofluorimetric [ 13,14 ] , and chromatographic methods such as HPLC. [ 15,17 ] In addition, it is considered as a simple method compared with the previously reported LC papers suffering from consuming large volumes of organic solvents in sample preparations, requiring a sophisticated instrument and high cost mass detector.…”

“…The sample was then treated with 5 ml of 0.2 M sulfuric acid and allowed to stand for 10 min for full hydrolysis of CMS converting into CS. [ 14 ] The reaction was then terminated by adding 10 ml of 0.2 M sodium hydroxide. Neutralization was confirmed using a pH meter.…”

“…Unfortunately, these published approaches relied on time‐consuming, high‐temperature derivatization of the medications, with NBD‐Cl for poly B [ 13 ] and the Hantzsch reaction for CS. [ 14 ] Conversely, the stated spectrophotometric techniques have several drawbacks such as poor sensitivity and the use of hazardous reagents or solvents.…”

“…A review of reported PMS quantification methods in bulk, pharmaceutical formulations, and biological fluids is provided. Considering spectroscopic methods, few ultraviolet (UV) spectrophotometric [ 8–12 ] and just two fluorimetric publications [ 13,14 ] , one for each antibiotic, have been reported previously. Furthermore, several chromatographic techniques such as high performance liquid chromatography (HPLC), [ 15–23 ] liquid chromatography (LC), [ 24–33 ] thin layer chromatography (TLC), [ 10,34 ] ultrahigh performance liquid chromatography (UPLC) [ 35–37 ] , and electrophoretic techniques [ 38–41 ] have been published.…”

“…Results for analysis of Colomycin ® , contain CMS the prodrug of CS, by proposed and compared with the reference method[14] Standard addition technique for estimation of poly B in Paximid ® vial by the proposed method Application of the proposed method for the determination of poly B and CS in spiked human plasma…”