Showing papers by "Juan A. Squella published in 1992"
TL;DR: UV degradation product, which was isolated and identified, showed that irradiation of nimodipine causes oxidation of the dihydropyridine ring and transmutation of the Nitro group in the nitrobenzene moiety.
29 citations
TL;DR: In this article, the electroactivity of the nitro group was used in order to develop a new polarographic method, which was applied to commercial samples [tablets] of two different pharmaceutical laboratories.
Abstract: Nimodipine is a calcium-channel blocker primarily used for its cerebral vasodilatory effect. The compound produces a d.p. polarographic peak due to the reduction of the nitro to the hydroxylamine group in a four electron process. The electroactivity of the nitro group was used in order to develop a new polarographic method. Furthermore, the UV absorption band at 360 nm of nimodipine was used as a comparative UV spectrophotometric method. The polarographic assay was applied to commercial samples [tablets] of two different pharmaceutical laboratories. Adequate precision and accuracy were obtained, thefore, the developed method is strongly recommended for uniformity content studies and stability test of nimodipine in routine analysis.
20 citations
TL;DR: In this paper, a 1, 4-dihydropyridine derivative, CRE-319, produces a cathodic polarographic peak due to the reduction of its nitro group according to the following well-known general pathway for the nitro groups: the electrode mechanism is strongly dependent on the pH of the solution and follows a similar behaviour to that previously reported for nitrobenzene.
Abstract: CRE-319, a novel 1, 4-dihydropyridine derivative, produces a cathodic polarographic peak due to the reduction of its nitro group according to the following well-known general pathway for the nitro group: The electrode mechanism is strongly dependent on the pH of the solution and follows a similar behaviour to that previously reported for nitrobenzene. The peak current shows a linear dependence with CRE-319 concentrations. This behaviour is used for analytical purposes in determining CRE-319 content in solution. In order to obtain comparative results, we have also developed a spectrophotomebic and an HPLC method for quantifying CRE-3 19.
11 citations
TL;DR: Nicergoline is an excellent model for the previously developed theory related to the effects of strong adsorption of electroactive species in voltammetry and was used to develop a new differential pulse polarographic method for the determination of the drug in pharmaceutical dosage forms.
4 citations
TL;DR: In this article, the amphetamine derivative 4,5-dimethoxy-2-nitrophenyl-2aminopropane, a positional isomer of the potent hallucinogen DON, was studied by cyclic voltammetry and polarography.
Abstract: The amphetamine derivative 4,5-dimethoxy-2-nitrophenyl-2-aminopropane, a positional isomer of the potent hallucinogen DON, was studied by cyclic voltammetry and polarography. The nitro compound was reduced to the corresponding hydroxylamine under the experimental conditions used.
2 citations