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We describe the effects of ethanol on the phase behavior of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in n-heptane. Using dynamic light scattering (DLS), molecular dynamics (MD) simulations, and nuclear magnetic resonance (1H NMR) spectroscopy, we investigate the aggregation behavior of AOT across a wide range of ethanol/AOT/n-heptane compositions. We conclude that reverse micelles do not form at any of the investigated concentrations. Instead, we observe the formation of other surfactant aggregate morphologies unique to this system, namely, multilayered cylindrical structures and spherical AOT-in-ethanol structures, which vary significantly with changes in ethanol concentration. We also identify mixed-solvent polarity as a driving factor for the surfactant behavior in the system. When the concentration of ethanol is 20 wt % or below, the system is inhomogeneous with varying sizes of AOT, ethanol, and AOT + ethanol aggregates, with the ethanol primarily exhibiting a cosurfactant behavior, almost exclusively binding at the surface of AOT aggregates. With increased ethanol concentration, the ethanol in the system also exhibits solvent-like behaviors in addition to the cosurfactant behaviors. Most significantly, when the ethanol concentration is raised above 35 wt %, the transition to solvent-like behavior allows AOT Na+ counterions to dissociate from the headgroups and they are dissolved in the ethanol. We use these results to construct a preliminary phase diagram for the ethanol/AOT/n-heptane system.
RESUMO
INTRODUCCIÓN La fenitoína es usada con mucha frecuencia en nuestro medio, por lo que se requiere hacer estudios de monitorización terapéutica, que contribuya a minimizar los efectos adversos y optimizar la terapia farmacológica. En ese contexto, nuestro objetivo ha sido determinar el índice nivel/dosis de la fenitoína en pacientes epilépticos voluntarios de Mérida. MÉTODOS Se realizó un estudio descriptivo, observacional y por reclutamiento consecutivo concurrente, conformado por 30 pacientes voluntarios con diagnóstico de epilepsia. Las muestras de suero se obtuvieron en niveles mínimos de pacientes que estaban en tratamiento con fenitoína durante 1 mes. Los niveles del fármaco se cuantificaron por el método de Inmunoensayo de enzima donante clonada en el equipo Indiko Thermo Scientific. RESULTADOS El índice nivel/dosis fue de 1,4 y 1,6, la concentración plasmática de 4,8mg/l y 8,0mg/l, la capacidad metabólica de 388,4 y 462,9mg/día, respectivamente en mujeres y hombres. Mientras que el nivel de la concentración plasmática en el estado estacionario fue de 6,5mg/l y 5,5mg/l, la dosis de carga máxima de 237,3mg y de 395,6mg, respectivamente en mujeres y hombres con epilepsia de la ciudad de Mérida. CONCLUSIONES Nuestros resultados sugieren que se debe individualizar la dosis en base al índice nivel/dosis de cada paciente, ya que no se puede extrapolar para todos los pacientes con epilepsia, debido a diversos factores como al fenotipo metabólico y al uso de fármacos inductores e inhibidores enzimáticos.
INTRODUCTION Phenytoin is used very frequently in our environment, so it is necessary to do studies of therapeutic monitoring, which helps to minimize adverse drug reaction and optimize pharmacological therapy. In this context, our objective was to determine the level/dose index of phenytoin in volunteer epileptic patients from Mérida. METHODS A descriptive, observational and consecutive concurrent recruitment study was carried out, consisting of 30 volunteer patients with a diagnosis of epilepsy. The serum samples were obtained in minimum levels from patients who were in treatment with phenytoin for 1 month. The levels of the drug were quantified by the method of donor enzyme immunoassay cloned in the Indiko Thermo Scientific equipment. RESULTS The level/dose index was 1,4 and 1,6, the plasma concentration of 4,8mg/l and 8,0mg/l, the metabolic capacity of 388,4 and 462,9mg/day, respectively in women and men. While the level of plasma concentration at steady state was 6,5mg/l and 5,5mg/l, the maximum loading dose of 237,3mg and 395,6mg, respectively in women and men with epilepsy of the city of Mérida. CONCLUSIONS Our results suggest that the dose should be individualized based on the level/dose index of each patient, since it can not be extrapolated for all patients with epilepsy, due to various factors such as the metabolic phenotype and the use of enzyme-inducing drugs and inhibitors.
