Showing papers by "Juan A. Squella published in 1997"
TL;DR: In this article, a very well resolved diffusion controlled differential pulse polarographic peak obtained at pH 7 was used to develop a new method for the determination of nimesulide in pharmaceutical dosage forms and the recovery study (104.8% with a RSD of 1.3%) showed that the method is sufficiently accurate and precise to be applied in the individual tablet assay of commercial samples.
Abstract: Nimesulide, N-(4-nitro-2-phenoxyphenyl)methanesulfonamide is an antiinflamatory analgesic agent that is both reducible at the mercury electrode and oxidizable at the glassy carbon electrode. Nimesulide in hydroalcoholic solution, presents cathodic response in a wide range of pH (2–12), both, by differential pulse and tast polarography techniques. The obtained results show only one main well-defined peak or wave in all the pH range studied. This peak (or wave) corresponds to the nitro group reduction in position 4. The voltammetric oxidation shows one well-resolved signal in all the pH range studied. This anodic signal could be attributed to the methylsulfonamide group oxidation. For analytical purposes, a very well resolved diffusion controlled differential pulse polarographic peak obtained at pH 7 was selected. This peak was used to develop a new method for the determination of nimesulide in pharmaceutical dosage forms. The recovery study (104.8% with a RSD of 1.3%) shows that the method is sufficiently accurate and precise to be applied in the individual tablet assay of commercial samples.
29 citations
TL;DR: It is concluded that the interaction process requires certain proton activity in the media and the following tentative order of reactivity towards the xeno/endobiotics is as follows: cysteamine > glutathione > adenineuracil.
24 citations
TL;DR: In this paper, cyclic voltammetry of two 1,4-benzodiazepines, loprazolam and flunitrazepam, was performed in a cyclic manner.
23 citations
TL;DR: In this article, cyclic voltammetric technique has been employed to study the tendency of ArNO 2.− to undergo further chemical reaction, and second order kinetics for the decay of the nitro radical anion were established for all the 1,4-dihydropyridines examined.
21 citations
TL;DR: A differential pulse polarographic method for the quantitative determination of ketorolac is described and recovery study shows that the method is sufficiently accurate and precise to be applied in the individual tablet assay of commercial samples.
15 citations
01 Sep 1997-Comparative Biochemistry and Physiology Part C: Pharmacology, Toxicology and Endocrinology
TL;DR: Nicardipine was found to be the most potent derivative in both growth cell and oxygen uptake and oxygen consumption on Tulahuen and LQ strains and clone Dm 28c of epimastigotes of Trypanosoma cruzi.
10 citations
TL;DR: In this paper, the electrochemical reduction of three nitrotetralone derivatives by tast and differential pulse polarography and cyclic voltammetry in a wide pH range was studied.
10 citations
TL;DR: In this article, a HPLC procedure with electrochemical detection in order to quantify ketorolac in pharmaceutical dosage forms is presented, and comparative methods using UV spectrophotometry and HPLC with photodiode array detector were used.
Abstract: Ketorolac is an antiinflammatory-analgesic agent that is oxidizable at the glassy carbon electrode. The voltammetric oxidation produces two well resolved pH-dependent peaks, that are overlapped at pH>10. Using this voltammetric response a HPLC procedure with electrochemical detection in order to quantify ketorolac in pharmaceutical dosage forms is presented. Furthermore comparative methods using UV spectrophotometry and HPLC with photodiode array detector were used.
6 citations
TL;DR: Results show that the increase of the NADPH-oxygen consumption induced by the drug, was not dependent on the respiratory chain of the parasite, providing an indirect proof of the nitro anion formation.
5 citations