Novel spectrophotometric method for the determination of azithromycin in pharmaceutical formulations based on its charge transfer reaction with quinalizarin

Abstract

Neste trabalho é proposto um novo método para a determinação espectrofotométrica simples e rápida de azitromicina em formulações farmacêuticas. O método está baseado na reação de transferência de carga entre a azitromicina e a quinalizarina em meio de metanol. O efeito de diversas variáveis foi avaliado com o intuito de alcançar máxima sensibilidade analítica. A reação de transferência de carga foi caracterizada, sendo determinadas a estequiometria da reação, a absortividade molar aparente e a constante de associação. Melhores resultados foram obtidos em meio de metanol e com uma concentração de quinalizarina de 50 mg L -1 . Nestas condições, o ânion radicalar (produto da reação de transferência de carga) foi formado imediatamente após a mistura dos reagentes, apresentando máxima absorção em 564 nm. O método apresentou um limite de detecção de 0,35 mg L -1 e um limite de quantificação de 1,2 mg L -1 , sendo aplicado com sucesso na determinação de azitromicina em três amostras de medicamentos comerciais contendo azitromicina. This paper proposes a new method for simple and fast spectrophotometric determination of azithromycin in pharmaceutical formulations. The method is based on the charge transfer reaction between the azithromycin and quinalizarin in methanol medium. In order to achieve maximum sensitivity the effect of some chemical variables such as the type of solvent, reagent concentration and reaction time were evaluated. The reaction was characterized in terms of stability of the product formed and its stoichiometry, and the apparent molar absorptivity and association constant were derived. Best conditions for the analytical determination of azithromycin were observed in methanol medium with a quinalizarin concentration of 50 mg L -1 . At these conditions, the radical anion (absorbing specie) was formed in the medium immediately after mixing of the reagents and showed maximum absorption at 564 nm. The method presented a limit of detection of 0.35 mg L -1 and a limit of quantification of 1.2 mg L -1 . It was successfully applied in the determination of azithromycin in three commercial pharmaceutical formulations of azithromycin and no matrix interferences were observed.

New Spectrophotometric and Conductometric Methods for Macrolide Antibiotics Determination in Pure and Pharmaceutical Dosage Forms Using Rose Bengal

“…e British Pharmacopoeia (BP) stated the liquid chromatography method for the assay of erythromycin, clarithromycin and azithromycin [5]. Also, the cited drugs have been analyzed spectrophotometrically in pharmaceutical dosage forms and biological �uids [6][7][8][9][10] and spectro�uorimetrically [11,12]. Other methods have been published for the cited drugs either in pharmaceutical preparations and biological �uids such as capillary electrophoresis [13,14], HPLC [15][16][17], and voltametry [18].…”

Spectrophotometric Determination of Macrolides Using Bromocresol Green in Pharmaceutical Formulations and Urine Samples

“…It has been observed that, the BCG methods have wider linear ranges as compared to most of the reported methods [11][12][13][14] . These proposed methods are more sensitive compared to some of the established methods as shown by the molar absorptivity 11,14,17 . The detection limits are lower than the reported methods 11,14 .…”

“…These proposed methods are more sensitive compared to some of the established methods as shown by the molar absorptivity 11,14,17 . The detection limits are lower than the reported methods 11,14 . These methods utilized a single step reaction with no extraction process and so simpler compared to reported methods 14,16 .…”

Development and Validation of a UV-Spectrophotometric Method for Determination of Flucloxacillin Sodium in Capsules

“…The results showed that the percentage drug is in accordance with the British, European and Portuguese Pharmacopoeias, which permit flucloxacillin sodium in capsules to be in a range of 92.5 to 110.0% of the content label claim. UV, UV-VIS and Derivative spectrophotometry are broadly used techniques to quantify antibiotics and other drugs [28][29][30][31][32][33][34][35] because they are inexpensive, simple and do not require time-consuming sample preparation compared with others techniques [36]. Moreover, UV-spectrophotometry produces very low amounts of residues and solvents, which is an important ecological aspect currently discussed in routine laboratory analysis.…”