Flow microcalorimetric assay of antibiotics--III. Zinc bacitracin and its combinations with polymyxin B sulphate and neomycin sulphate on interaction with Micrococcus luteus

Full green assay of parenteral dosage forms of polymyxins utilizing xanthene dye: application to content uniformity testing

Due to the lack of other treatment options, a rebirth of polymyxins is urgently required. Colistin (also called polymyxin E) and polymyxin B are the only two examples of this antibiotic class that were effectively employed in such critical situations. In the present work, both of the two studied medications were quantified via a simple, green, and non-extracting spectrophotometric approach based on the formation of ion-pair complexes with Erythrosine B. Without using any organic solvents, the pink color of the created complexes was detected at wavelength = 558 nm. To achieve the highest intensity of absorbance, optimum conditions were established by the screening of many experimental factors such as pH, buffer volume, the volume of Erythrosine B, and the time consumed to undergo the reaction. For Colistin and Polymyxin B respectively, Beer-Lambert's law was observed at the concentration ranges of 1-6, 1-9 µg mL- 1. The technique was approved and validated following ICH recommendations. Lastly, the suggested approach has been successfully implemented to quantify the cited medications colorimetrically, for the first time, in their parenteral dosage forms with excellent recoveries. Also, Content uniformity testing was implemented.

Condensation methodology for quantification of Polymyxin B fluorimetrically: application to pharmaceutical formulations and greenness assessment

The appearance of multidrug-resistant Gram-negative bacterial infections, along with the lack of newly discovered antibiotics, resulted in the return to old antimicrobial medications like Polymyxins. As a result, the suggested technique aims to develop a fast, environmentally friendly, and sensitive fluorimetric method for quantifying Polymyxin B. The investigated approach depends on generating a highly fluorescent derivative by a condensation pathway between the studied drug and ninhydrin in the presence of phenylacetaldehyde and then estimated spectrofluorimetrically. After the reaction conditions were well optimized, the fluorescent product was estimated at emission wavelength (λem) = 475.5 nm (following excitation at a wavelength (λex) = 386 nm. The developed calibration plot displayed rectilinear throughout the following range (0.2-3 µg mL- 1), and the calculated limit of detection and quantification were 0.062 µg mL- 1 and 0.187 µg mL- 1, respectively. As a consequence, the drug's ophthalmic and intravenous pharmaceutical forms were both successfully quantified with an excellent degree of recovery. Finally, the methodology's greenness was assessed utilizing Analytical Eco-Scale scores.

Flow microcalorimetric assay of antibiotics--IV. Polymyxin B sulphate, neomycin sulphate, zinc bacitracin and their combinations with Escherichia coli suspended in buffer plus glucose medium

Flow microcalorimetric assays for polymyxin B sulphate and neomycin sulphate have been developed using Escherichia coli as the test organism, suspended in a glucose plus buffer medium. These assays have a better reproducibility (relative standard deviations 3.2 and 2.0%, respectively), and require a shorter time (1 h including time required for preparation of the calorimeter) than do conventional microbiological assays, but are not as sensitive. It is suggested that a screening programme might produce a small group of more suitable (i.e. more sensitive) test organisms, which could be used to develop rapid and reproducible flow microcalorimetric assays for a wide range of antibiotics by the procedure described. The effect of combinations of polymyxin B sulphate, neomycin sulphate and zinc bacitracin (the antibiotic components of the commercial preparation Trisep, ICI, Macclesfield, UK) on the power output of cells suspended in glucose plus buffer medium is also reported. In defined combinations, the effects of neomycin sulphate appeared to be exerted before those of polymyxin B sulphate.