Development and validation of a rapid turbidimetric assay to determine the potency of norfloxacin in tablets

Abstract

Norfloxacin is one of the first commercially available (and most widely used) fluoroquinolone antibiotics. This paper reports the development and validation of a simple, sensitive, accurate and reproducible turbidimetric assay method to quantify norfloxacin in tablets formulations in only 4 hours. The bioassay is based on the inhibitory effect of norfloxacin upon the strain of Staphylococcus epidermidis ATCC 12228 IAL 2150 used as test microorganism. The assay was performed 3x3 parallel lines like, three tubes for each concentration of reference substance and three tubes for each sample concentration. The results were treated statistically by analysis of variance and were found to be linear (r 2 = 0.9999) in the selected range of 25-100 μg mL -1 ; precise (intra-assay: relative standard deviation (RSD) = 1.33%; inter-assay: RSD = 0.21%), accurate (100.74%) and robust with RSD lower than 4.5%. The student's t-test showed no statistically significant difference between the proposed turbidimetric method and an HPLC method previously validated. However the turbidimetric assay can be used as a valuable alternative methodology for the routine quality control of this medicine, complementary to other physical-chemical methods.Uniterms: Microbiological assay. Quality control. Norfloxacin/quantification in tablets. Turbidimetric method/quality control/validation. Antimicrobials/quality control.O norfloxacino foi a primeira fluorquinolona (e mais utilizada) disponível no mercado. Este trabalho divulga um novo desenvolvimento e validação de um método turbidimétrico simples, sensível, preciso e reprodutível para a quantificação de norfloxacino em comprimidos em apenas 4 horas. O bioensaio é baseado no efeito inibitório de norfloxacino sobre a cepa Staphylococcus epidermidis ATCC 12228 IAL 2150, utilizada como micro-organismo teste. O bioensaio foi efetuado através do delineamento de linhas paralelas 3x3, em que três tubos foram utilizados para a solução padrão e três tubos para as concentrações da amostra. Os resultados foram tratados estatisticamente pela análise de variância, apresentando coeficiente de correlação linear de r 2 = 0,9999, na faixa de 20 a 100 μg mL -1 ; precisão (intra-ensaio: desvio padrão relativo (RSD) 1,33%; inter-ensaio: RSD=0,21%), exatidão (100,74%) e robustez com RSD menor que 4,5%. O teste-t mostrou não haver diferença estatisticamente significativa entre o método turbidimétrico proposto e um método por HPLC previamente validado. No entanto, o ensaio turbidimétrico pode ser utilizado como método alternativo para o controle de qualidade de rotina para este antimicrobiano, como um complemento de outros métodos físico-químicos.Unitermos: Ensaio microbiológico. Norfloxacino/quantificação em comprimidos. Método turbidimétrico/ controle de qualidade/validação. Antimicrobianos/controle de qualidade.

Evolution of green chemistry and its multidimensional impacts: A review

“…In the literature there are many physical-chemical and microbiological methods for the evaluation of drugs and pharmaceuticals which contemplate green analytical chemistry items such as HPLC methods using only ethanol and water in the mobile phase (Tótoli and Salgado, 2014, Pedroso et al, 2016, Spagnol et al, 2016, Rodrigues and Salgado, 2016, Figueiredo et al, 2017, Kogawa et al, 2017, Marco and Salgado, 2017), spectrophotometry in the ultraviolet region (UV) using aqueous solution as diluent (Kogawa and Salgado, 2013, Alessio et al, 2017, Kogawa and Salgado, 2016), spectrophotometry in the visible region (Vis) using aqueous solution as diluent (Brbaklic et al, 2017, Rechelo et al, 2017), spectrophotometry in the infrared region (IR) using only potassium bromide as reagent (Moreno and Salgado, 2012, Tótoli and Salgado, 2012, Vieira et al, 2012, Kogawa and Salgado, 2013, Piantavini et al, 2014, Mallah et al, 2015, Marco and Salgado, 2016, Trindade and Salgado, 2017), capillary electrophoresis (CE) with migration time less than 5 min (Kogawa et al, 2014, Tótoli et al, 2015, Chierentin et al, 2016) and microbiological methods with results in 4 h (Kogawa et al, 2012, Tótoli and Salgado, 2013, Cazedey and Salgado, 2013, Vieira et al, 2014, Pedroso and Salgado, 2014, Chierentin and Salgado, 2015, Silva and Salgado, 2015, Tótoli and Salgado, 2015, Curbete and Salgado, 2016, Kogawa and Salgado, 2016).…”

“…A time-consuming method that releases results within 24 h or more, such as microbiological results for antibiotics, will make products expensive or, if released without this analysis, perhaps inefficient which can promote the overload of the health system and contribute to microbial resistance (Kogawa et al, 2012, Tótoli and Salgado, 2013, Cazedey and Salgado, 2013, Vieira et al, 2014, Pedroso and Salgado, 2014, Chierentin and Salgado, 2015, Silva and Salgado, 2015, Tótoli and Salgado, 2015, Curbete and Salgado, 2016, Kogawa and Salgado, 2016).…”