Biostimulatory effects of simvastatin on MDPC-23 odontoblast-like cells

Abstract: The aim of this study was to evaluate the bioactivity and cytocompatibility of simvastatin (SV) applied to MDPC-23 odontoblast-like cells. For this purpose, MDPC-23 cells were seeded in 96-well plates and submitted to treatments with 0.01 or 0.1 μM of SV for 24 h, 72 h or continuously throughout the experimental protocol. The negative control group (NC) was maintained in DMEM. Cell viability (MTT), ALP activity (thymolphthalein monophosphate), and mineralized matrix deposition (alizarin red) were analyzed at several time points. The data were submitted to ANOVA and Tukey's test (α = 0.05). Although cell viability was observed in the groups treated with SV, these groups did not differ from the NC up to 7 days. There was a reduction in cell viability for the groups treated with 0.1 μM of SV for 72 h, and submitted to continuous mode after 14 days. A significant increase in ALP activity occurred in the group treated with 0.01 μM of SV for 24 h, compared with the NC; however, only the group treated with 0.1 μM of SV in continuous mode reduced the ALP activity, in comparison with the NC. After 14 days, only continuous treatment with 0.1 μM of SV did not differ from NC, whereas the other experimental groups showed increased mineralized matrix deposition. Thus, it was concluded that low concentrations of simvastatin were bioactive and cytocompatible when applied for short periods to cultured MDPC-23 odontoblast-like cells.

Sensitive and rapid titrimetric and spectrophotometric methods for the determination of stavudine in pharmaceuticals using bromate-bromide and three dyes

Four sensitive and rapid methods for the determination of stavudine (STV) in bulk drug and in dosage forms were developed and optimized. In titrimetry, aqueous solution of STV was treated with a known excess of bromate-bromide in HCl medium followed by estimation of unreacted bromine by iodometric back titration. Spectrophotometric methods involve the addition of a measured excess of bromate-bromide in HCl medium and subsequent estimation of the residual bromine by reacting with a fixed amount of methyl orange, indigocarmine or thymol blue followed by measurement of absorbance at 520 nm (method A), 610 nm (method B) or 550 nm (method C). In all the methods, the amount of bromate reacted corresponds to the amount of STV. Calculations in titrimetry were based on a 1:0.666 (STV:KBrO3) stoichiometry and the method was found to be applicable over 3.5-10 mg range. A linear increase in absorbance with concentration of STV was observed in the spectrophotometric methods, and the Beer's law was obeyed over the concentration ranges 0.125-1.75, 1-10 and 1-9.0 µg mL-1 STV for method A, method B and method C, respectively. The methods when applied to the determination of STV in tablets and capsules were found to give satisfactory results.

Este trabalho descreve quatro métodos rápidos e sensíveispara a determinação de estavudina (STV) na matéria-prima ou em produtos formulados. Soluções aquosas de STV podem ser tituladas tratando-as com excesso de bromato-brometo em meio ácido clorídrico, seguido da determinação iodimétrica de bromo em excesso. Métodos espectrofotométricos tambémenvolvem a adição de excesso de bromato-brometo à amostra, seguida da determinação de bromo residual por adição de uma quantidade fixa de alaranjado de metila, índigo-carmim ou azul de timol, e de medidas de absorbância nos comprimentos de onda apropriados: 520, 610 ou 550 nm. Em todos os métodos, a quantidade de bromato consumida corresponde à quantidade de STV e os resultados da sua aplicação à determinação de STV em comprimidos e cápsulas são satisfatórios.