ABSTRACT
La formulación de dispersiones sólidas es un método efi caz de aumento de la velocidad de disolución de fármacos muy poco solubles. El objetivo de este estudio fue la preparación y caracterización de dispersiones sólidas de oxazepam con carbómero 934P para mejorar sus propiedades de disolución. Las dispersiones sólidas se prepararon mediante el método de disolución y se compararon las velocidades de disolución de dispersiones sólidas con las de las mezclas físicas y el fármaco puro. La evaluación de las características de las dispersiones sólidas se realizó mediante espectroscopia de infrarrojos (IR), difractometría de rayos X (R-X), calorimetría diferencial de barrido (DSC) y ensayo de disolución. Los datos de IR, R-X y DSC no mostraron interacción fármaco-polímero. Los resultados obtenidos a partir de los estudios de disolución mostraron que la velocidad de disolución del oxazepam mejoraba considerablemente cuando se formulaba en dispersiones sólidas con carbómero 934P, en comparación con las de mezclas físicas y el oxazepam puro
The formulation of solid dispersions is an effective method of increasing the dissolution rate of poorly soluble drugs. The purpose of this study was to prepare and to characterize solid dispersions of oxazepam with carbomer 934P to improve their dissolution properties. Solid dispersions were prepared by dissolution method and the dissolution rates of solid dispersions were compared with those ones of physical mixtures and pure drug. The evaluation of solid dispersions characteristics was performed using infrared espectroscopy (IR), X-ray diffractometry (X-R), differential scanning calorimetry (DSC) and dissolution assay. IR, X-R and DSC data showed no drug-polymer interaction. The results obtained from dissolution studies showed that the dissolution rate of oxazepam was considerably better when it was formulated in solid dispersions with carbomer 934P compared with those of physical mixtures and pure oxazepam
Subject(s)
Oxazepam/chemistry , Spectroscopy, Near-Infrared/methods , Calorimetry, Differential ScanningABSTRACT
We analyzed the physicochemical characteristics of solid dispersions of pizotifen malate and povidone (Kollidon 12) at different proportions; we used X-ray diffraction, infrared spectrometry and differential scanning calorimetry (DSC) and tested the solubility of the solid dispersions in equilibrium. The results were compared with findings for physical mixtures with the same proportions. A solid dispersion with a drug proportion of 16%-17% formed a eutectic mixture. Solubility of pizotifen malate increased with the proportion of drug in the solid dispersion up to a drug:polymer ratio of 40:60. The hydrotropic effect of the polymer also favored solubility: In physical mixtures, this effect was greatest at a drug:polymer ratio of 10:90; solubility at this proportion was equal to that of the solid dispersion at the same proportion.
Subject(s)
Pizotyline/chemistry , Povidone/chemistry , Serotonin Antagonists/chemistry , Calorimetry, Differential Scanning , Crystallography, X-Ray , Pharmaceutic Aids , Solubility , Spectrophotometry, Infrared , Temperature , VibrationABSTRACT
The influence of adjuvants in suppository formulations on the release and absorption of sodium valproate, a water soluble anti-epileptic, was analysed in order to determine the optimal formula for rectal administration. Three formulations were prepared with Suppocire AS2(formula I), Aerosil R 972 (formula II) or Span 80 (formula III). In-vivo and in-vitro release-diffusion studies were performed using white laboratory rabbits as the experimental model. The adjuvants decreased the percentage release of valproic acid to 96.7% (formula I) and 84.1% (formula II), and delayed peak release-diffusion concentration (210 and 150 min, respectively, with formulas II and III in comparison with 120 min with formula I). Their effect on bioavailability was observed as an increase in plasma levels of the active substance, with areas under the plasma concentration/time curve of 396.26 and 306.64 micrograms h mL-1 (formulas II and III, respectively) and 243.28 micrograms h mL-1 (formula I). The time to peak plasma concentration was also delayed with peaks at 30, 55 and 50 min with formulas I, II and III, respectively.
