Electrochemical studies of ropinirole, an anti-Parkinson’s disease drug

Abstract

The oxidation behaviour of a potent anti-Parkinson's disease drug ropinirole hydrochloride was investigated over a wide pH range in aqueous solution at glassy carbon electrode using cyclic and square-wave voltammetry. The oxidation of drug is a pH dependent irreversible process and occurs in two steps. The mechanism of the oxidation process has been discussed. Using the sharp oxidation response in 0.1 M sulphuric acid at a potential of +1.27 V attributed to the oxidation of indol-2-one ring in drug molecule, rapid electroanalytical methods for the determination of ropinirole by pulse voltammetric techniques were developed and validated. The proposed voltammetric methods were applied to direct quantification of ropinirole in film-coated tablets, with results in close agreement (at 95% confidence level) with those obtained using a comparative HPLC method.

A novel electroanalytical nanosensor based on MWCNT/Fe2O3 nanoparticles for the determination of antiparkinson drug ropinirole

“…According to the literature, the proposed mechanism of RPN is first related to the indole group and secondly related to N atom in the aliphatic chain. These results are matching with the literatures [18] and [24] but there is a difference from the suggested mechanism by Nigovic et al [18] in the first step. We suggest hydroxylation from 6th and 7th carbon atoms in the indole ring for the first peak [42,43].…”

“…α was assumed equal to 0.5, n values are equal 2.02 (~2) for each peak. These two calculations verified each other and in accordance with literature [18,24].…”

“…The results indicated that the modified electrode significantly enhanced (nearly 13.5 times) the oxidation peak current of RPN compared to bare CPE using AdSDPV. The developed methods are more sensitive and have much lower detection limits (1.3×10 −3 μg mL −1 with AdSDPV and 4.08×10 −4 μg mL −1 with AdSSWV) as compared to previously reported methods at GCE (0.074 μg mL −1 with DPV and 0.033 μg mL −1 with SWV) [18] and at modified GCE (4.76×10 −3 μg mL −1 with AdSSWV) [24]. These methods provide a new way to construct a modified electrode for fast, simple, and low cost analysis of RPN from pharmaceutical dosage forms compared with other published methods.…”

“…The results were compared with other literature studies according to the linearity range, LOD and LOQ values in Table 2. As can be seen from the table, the modified electrode gave more sensitive results compared to the other voltammetric studies with glassy carbon electrode [18,24].…”

“…Until recently, there were many studies about RPN including spectroscopic methods [6][7][8][9], liquid chromatographic (LC) methods [6,[10][11][12][13][14][15][16][17][18], high performance (HP) thin layer chromatographic (TLC) methods [9,19], LC methods combined with tandem mass spectrometry (MS/MS) [20] and with electrospray ionization-tandem mass spectrometry (ESI-MS/ MS) [21], chromatography with chemometric method [22], capillary zone electrophoretic (CZE) methods [23], and voltammetric methods [18,24]. The reported methods have many shortcomings such as potential loss of drugs in the reextraction procedure, need of lengthy, tedious, and time consuming plasma preparation and extraction process.…”