Edebi Nicholas Vaikosen*, Benjamin Umar Ebeshi and Chimenem Ruth Worlu Pages 487 - 496 ( 10 )
Background: Aminoglycosides are non-chromophoric antibiotics. The official method of assay in pharmacopoeias is microbiological. Bioassay methods are potency-semi-quantitative, laborious and time-consuming. In contrast, spectrophotometric methods are rapid, convenient, specific, sensitive and selective. The presence of NH2 and –OH functional groups in aminoglycosides makes them susceptible to redox reaction.
Objective: A simple, cheap, quick, accurate and reliable spectrophotometric method for aminoglycoside analysis using neomycin as prototype via oxidation by ammonium molybdate reagent is proposed.
Methods: Four aminoglycosides – amikacin, gentamicin, neomycin and streptomycin, were oxidized using ammonium molybdate (pH<2). These were scanned to obtain visible-spectrophotometric fingerprints. Two assay methods were developed. Method I involved the determination of the drug via the linear proportionality between neomycin and residual molybdate measured at 780nm and 850nm. Method II, an indirect determination using ion-pair reaction of excess molybdate and methyl orange measured at 430nm and 480nm.
Results: All aminoglycosides formed blue complex, with distinct spectra peaks at 500nm, 640nm, 780nm and 850nm.The limit of detection and limit of quantification were from 0.33 to 2.32 μgmL-1 and 1.00 to 7.03 μgmL-1 respectively for both methods. Percentage recoveries ranged from 89.60 and 113.05 %, while precision and accuracy as RSD ranged from 0.23 to 3.55%. The regression coefficient (R2) ranged from 0.9968 to 0.9995. Percentage neomycin in dosage forms ranged from 95.67- 104.16% and 96.04 - 99.46% for methods I and II, respectively.
Conclusion: The methods were successfully applied for neomycin sulphate determination in tablets and drops, therefore aminoglycosides could be assayed via the proposed methods.
Antibiotics, aminoglycosides, non-chromophoric, indirect spectrophotometry, oxidative, methyl orange.
Department of Pharmaceutical and Medicinal Chemistry, Faculty of Pharmacy, Niger Delta University, Wilberforce Island, Bayelsa State, Department of Pharmaceutical and Medicinal Chemistry, Faculty of Pharmacy, Niger Delta University, Wilberforce Island, Bayelsa State, Department of Pharmaceutical and Medicinal Chemistry, Faculty of Pharmacy, Niger Delta University, Wilberforce Island, Bayelsa State