Electrochemical behavior of disopyramide and its adsorptive stripping determination in pharmaceutical dosage forms and biological fluids

Nano optical and electrochemical sensors and biosensors for detection of narrow therapeutic index drugs

For the first time, a comprehensive review is presented on the quantitative determination of narrow therapeutic index drugs (NTIDs) by nano optical and electrochemical sensors and biosensors. NTIDs have a narrow index between their effective doses and those at which they produce adverse toxic effects. Therefore, accurate determination of these drugs is very important for clinicians to provide a clear judgment about drug therapy for patients. Routine analytical techniques have limitations such as being expensive, laborious, and time-consuming, and need a skilled user and therefore  the nano/(bio)sensing technology leads to high interest.

Adsorptive stripping voltammetric methods for determination of aripiprazole

Anodic behavior of aripiprazole (ARP) was studied using electrochemical methods. Charge transfer, diffusion and surface coverage coefficients of adsorbed molecules and the number of electrons transferred in electrode mechanisms were calculated for quasi-reversible and adsorption-controlled electrochemical oxidation of ARP at 1.15 V versus Ag/AgCl at pH 4.0 in Britton–Robinson buffer (BR) on glassy carbon electrode. Voltammetric methods for direct determination of ARP in pharmaceutical dosage forms and biological samples were developed. Linearity range is found as from 11.4 μM (5.11 mg/L) to 157 μM (70.41 mg/L) without stripping mode and it is found as from 0.221 μM (0.10 mg/L) to 13.6 μM (6.10 mg/L) with stripping mode. Limit of detection (LOD) was found to be 0.11 μM (0.05 mg/L) in stripping voltammetry. Methods were successfully applied to assay the drug in tablets, human serum and human urine with good recoveries between 95.0% and 104.6% with relative standard deviation less than 10%.

Electrochemical oxidation of atorvastatin and its adsorptive stripping determination in pharmaceutical dosage forms and biological fluids

Electrochemical behavior of atorvastatin (AT) and optimum conditions to its quantitative determination were investigated using voltammetric methods. Some electrochemical parameters such as diffusion coefficient, surface coverage of adsorbed molecules, electron transfer coefficient, standard rate constant and number of electrons were calculated using the results of cyclic voltammetry. A tentative mechanism for the oxidation for AT has been suggested. The oxidation signal of AT molecule was used to develop fully validated, new, rapid, selective and simple square-wave anodic adsorptive stripping voltammetric (AdsSWV) and differential pulse anodic stripping voltammetric (AdsDPV) methods to direct determination of AT in pharmaceutical dosage forms and biological samples. For the AdsDPV and AdsSWV techniques, linear working ranges were found to be 1.0 × 10–7–5.0 × 10–6and 3.0 × 10–7–5.0 × 10–6mol l–1, respectively. The detection limits obtained from AdsDPV and AdsSWV were calculated to be 6.55 × 10–8and 1.53 × 10–7mol l–1, respectively. The methods were successfully applied to assay the drug in tablets, human blood serum and human urine.

Electrochemical behavior of Moclobemide at mercury and glassy carbon electrodes and voltammetric methods for its determination

Electrochemical oxidation and reduction properties of Moclobemide (MCB) were investigated at glassy carbon electrode (GCE) and hanging mercury drop electrode (HMDE). Diffusion-adsorption behavior and some extra electrochemical parameters such as diffusion coefficient, number of transferred electrons and proton participated to its electrode mechanisms on both electrode and surface coverage coefficient were calculated from the results of cyclic voltammetry and square-wave voltammetry. Reversible catalytic hydrogen wave mechanism was proposed at HMDE and single two-electron/two-proton irreversible oxidation mechanism controlled by adsorption with some diffusion contribution at GCE was proposed. Experimental parameters were optimized to develop new, accurate, rapid, selective and simple voltammetric methods for direct determination of MCB in pharmaceutical dosage forms and spiked human serum samples without time-consuming steps prior to drug assay. In these methods, the lowest limit of detection (LLOD) was found to be 0.0235 μM. Methods were successfully applied to determine the MCB content of commercial pharmaceutical preparations and spiked human urine. The methods were found to be highly accurate and precise.

Square-wave cathodic adsorptive stripping voltammetry of risperidone

Electrochemical properties and diffusion-adsorption behavior of risperidone (RPN), an antiphyscotic drug, on hanging mercury drop electrode (HMDE) were carried out in Britton–Robinson (BR) buffer. Some electrochemical parameters such as diffusion coefficient, number of transferred electrons and proton participated to its reduction mechanism and surface coverage coefficient were calculated from the results of cyclic voltammetry, square-wave voltammetry and constant potential electrolysis. RPN was found to be reduced with single two-electron/two-proton quasi-reversible mechanism controlled mainly by adsorption with some diffusion contribution at the potential about –1.58 V (vs Ag|AgCl electrode). Experimental parameters were optimized to develop a new, accurate, rapid, selective and simple square-wave cathodic adsorptive stripping voltammetric (SWCAdSV) method for direct determination of RPN in pharmaceutical dosage forms, spiked human urine and human serum samples without time-consuming steps prior to drug assay. This method was based on the relation between the peak current and the concentration of RPN and it was recognized that peak current of reduction wave linearly changes with the concentration of RPN in the concentration range of 1.5–150 nM, when optimum preconcentration potential –0.65 V and optimum preconcentration time 60 s were applied. In this method, limit of detection (LOD) was found as 5.18 nM (2.12 ppb). The method was successfully applied to determine the RPN content of commercial pharmaceutical preparations, spiked human serum and spiked human urine. The method was found to be highly accurate and precise, having a relative standard deviation of less than 4.80% for all applications.