Voltammetric behavior of amfepramone (diethylpropion) at the hanging mercury drop electrode and its analytical determination in pharmaceutical formulations

Abstract

Este trabalho descreve um estudo sistemático do comportamento voltamétrico da anfepramona no eletrodo de mercúrio de gota pendente (HMDE) por voltametria cíclica (CV) e voltametria de corrente alternada (AC). Os estudos mostraram o comportamento adsortivo da anfepramona no HMDE e foram realizados em soluções de H 2 SO 4 0,1 mol L -1 (pH 1.0) e tampão de Ringer (pH 11,0) como eletrólito suporte. A faixa linear para a determinação de anfepramona por voltametria de pulso diferencial de varredura linear (DPV) foi de 0,05 a 2,0 mg L -1 (r = 0,998) em meio ácido e de 0,25 a 4,0 mg L -1 (r = 0,994) em meio alcalino. Os desvios padrão relativos calculados para 5 medidas de anfepramona 0,5 mg L -1 em meio ácido e meio alcalino foram de 2,5 e 4,0%, respectivamente. Os limites de detecção calculados para a determinação de enfepramona em meio ácido e meio alcalino foram de 0,035 e 0,18 mg L -1 , respectivamente. As metodologias foram aplicadas para a determinação de anfepramona por DPV em cápsulas e comprimidos de formulações farmacêuticas usadas no tratamento da obesidade. Os valores de recuperação entre 90,0 e 101,0% para anfepramona adicionada a misturas sintéticas contendo femproporex, mazindol, sibutramina, fluoxetina, cafeína, diazepan e metformina provam a aplicabilidade do método para a sua determinação na presença de outras drogas normalmente adicionadas de forma ilegal a formulações farmacêuticas comercializadas como medicamentos naturais.This paper describes a systematic study of the voltammetric behavior of amfepramone at the hanging mercury drop electrode (HMDE) by cyclic (CV) and alternating current (AC) voltammetric methods. The studies showed the adsorptive behavior of amfepramone at the HMDE and were performed in H 2 SO 4 0.1 mol L -1 (pH 1.0) and Ringer buffer (pH 11.0) as supporting electrolytes. The linear range for the amfepramone determination by differential pulse voltammetry (DPV) was 0.05 to 2.0 mg L -1 (r = 0.998) in acidic medium and 0.25 to 4.0 mg L -1 (r = 0.994) in alkaline medium. The relative standard deviation calculated was 2.5% and 4.0 % for five measurements of 0.5 mg L -1 amfepramone in acidic and alkaline medium, respectively. The detection limits calculated for the amfepramone determination in acidic and alkaline medium were 0.035 e 0.18 mg L -1 , respectively. The methods were applied for the determination of amfepramone by DPV in tablets and capsules of pharmaceutical formulations used in the treatment of obesity. Recoveries values ranging from 90.0 to 101.0% for amfepramone added to synthetic mixtures containing fenproporex, mazindol, sibutramine, fluoxetine, caffeine, diazepam, and metformin as interferents prove the applicability of the method for its determination in the presence of other drugs normally added illegally to pharmaceutical formulations commercialized as natural medicaments. Keywords IntroductionThe abusive use of anorexics has grown lately, mainly because of its use in the treatment of obesity. The consumption of anorexics in Brazil is approximately 23.6 tons per y...

Presence of synthetic pharmaceuticals as adulterants in slimming phytotherapeutic formulations and their analytical determination

“…Among the electrochemical methods, voltammetry is the most often utilized technique for the analysis of phytotherapeutic adulteration [1,48,50]. Voltammetric methods enable the sensitive and selective measurement of organic compounds based on their specific electrochemical behavior at the working electrode surface [1,48].…”

“…Voltammetric methods enable the sensitive and selective measurement of organic compounds based on their specific electrochemical behavior at the working electrode surface [1,48]. Electrochemical methods are advantageous in comparison with separation methods (HPLC and CE).…”

“…Electrochemical methods are advantageous in comparison with separation methods (HPLC and CE). This is because they allow the measurement of a sample without the total solubilization and exhaustive filtration steps that are necessary for the separation of insoluble excipients, as for HPLC and CE [48,50]. Furthermore, voltammetric methods are advantageous with respect to the low cost of instrumentation and the short analysis time [1,48].…”

Voltammetric determination of sibutramine in beverages and in pharmaceutical formulations

“…20 Voltammetric methods enable the sensitive and selective measurement of organic compounds based on their specific electrochemical behavior at the working electrode surface. 21,22 Electrochemical methods are advantageous if the selectivity achieved eliminates the need for separation procedures, which simplifies procedures, enables short analysis times and lower cost of analysis by using a relatively cheaper instrument and less consumables. 23 In the present work, a simple and sensitive analytical method based on the differential pulse voltammetry was developed for the determination of sibutramine hydrochloride (sibutramine-HCl).…”

Simultaneous voltammetric determination of dypirone and paracetamol with carbon paste electrode and multivariate calibration methodology

“…To overcome these limitations, electrochemical methods, such as voltammetric ones were extensively used for their accuracies, precisions, simplicities and possibilities of analysis without tedious sample pre-treatment. 11,12 However, the quantification of two or more components of a pharmaceutical sample using electrochemical techniques is generally a challenge task since most of the active components tend to oxidize or reduce at potentials extremely close which hampers their simultaneous determination. The association of electrochemical methods, such as voltammetric techniques using unmodified carbon electrodes with multivariate calibration methods eliminates the need for previous separations and permits simultaneous determination in the presence of analytical signal interference.…”