Preparación y caracterización físicoquímica de una microemulsión de macrogol -8- glicéridos de caprilocaproilo para la administración oral de fármacos

The performance of caprylocapryl macrogol -8- glycerides in the development of pharmaceutically acceptable, stable, selfemulsifyingmicroemulsion was assessed. The suitability of the concentration of surfactant with respect to the oil phasewas assessed by interfacial tension measurement. A pseudoternary microemulsion system was constructed using caprylocaprylmacrogol -8- glycerides / polyglyceryl 6-dioleate / medium chain triglycerides and water. The model microemulsion wascharacterised with regard to its electroconductive behaviour and droplet size measurement after dilution with water aswell as with simulated gastric fluid, surface charge, centrifugal stability, viscosity and stability studies. The percolationtransition theory, which makes it possible to determine the percolation threshold and to identify the bicontinuousstructures, was applied to the system. The interfacial tension changes associated with the microemulsion formation showsultra low values upto 30% oil at a surfactant / cosurfactant ratio 4:1. Moreover, the investigated particle size after dilutionwith excess of water as well as with simulated gastric fluid proved the efficiency of the microemulsion system as a potentialcarrier for oral drug delivery.Se evaluó el rendimiento de los macrogol -8- glicéridos de caprilocaproilo en el desarrollo de una microemulsiónautoemulsionante, estable y aceptable desde el punto de vista farmacológico. Se evaluó la idoneidad de la concentraciónde surfactante en relación con la fase oleosa a través de la medición de la tensión interfacial. Se elaboró unsistema de microemulsiones pseudoternario con macrogol -8- glicéridos de caprilocaproilo/poligliceril 6-dioleato/triglicéridos de cadena media y agua. La microemulsión modelo se caracterizó en relación con su comportamientoelectroconductivo y la medición del tamaño de las gotitas tras su dilución en agua y fluido gástrico simulado, y serealizaron estudios de carga de superficie, estabilidad centrífuga, viscosidad y estabilidad. Se aplicó la teoría de latransición de percolación al sistema, lo que hizo posible la determinación del umbral de percolación y la identificaciónde las estructuras bicontinuas. Los cambios de tensión interfacial asociados a la formación de las microemulsionesmostraron valores muy bajos, hasta un 30% de aceite en una proporción 4:1 de surfactante/cosurfactante. Además,el tamaño de las partículas investigadas tras la dilución en agua abundante y en fluido gástrico simulado demostraronla eficacia del sistema de microemulsiones como un posible sistema de transporte para la administración oral defármacos

Thermoreversible-mucoadhesive Gel for nasal delivery of sumatriptan

The purpose of the present study was to develop intranasal delivery systems of sumatriptan using thermoreversible polymer Pluronic F127 (PF 127) and mucoadhesive polymer Carbopol 934P (C934P). Formulations were modulated so as to have gelation temperature below 34°C to ensure gelation at physiological temperature after intranasal administration. Gelation temperature was determined by physical appearance as well as by rheological measurement. The gelation temperatures of the formulations decreased by addition of increasing concentrations of Carbopol (ie, from 29°C for 18% PF127 to 23.9°C for 18% PF127, 0.5% Carbopol). The mucoadhesive force in terms of detachment stress, determined using sheep nasal mucosal membrane, increased with increasing concentration of Carbopol. The results of in vitro drug permeation studies across sheep nasal mucosa indicate that effective permeation coefficient could be significantly increased by using in situ gelling formulation with Carbopol concentration 0.3% or greater. Finally, histopathological examination did not detect any damage during in vitro permeation studies. In conclusion, the PF 127 gel formulation of sumatriptan, with in situ gelling and mucoadhesive properties with increased permeation rate is promising for prolonging nasal residence time and thereby nasal absorption

Influence of Rheology of Dispersion Media in the Preparation of Polymeric Microspheres through Emulsification Method

Chitosan microspheres as drug delivery system have attained importance and attracted the attention of researchers in last few years. This study was aimed toward the elucidation of the effect of viscosity of external oil phase on the properties of microspheres prepared by emulsification method. Chitosan microspheres were prepared utilizing oil phase of different viscosity viz. castor oil, heavy liquid paraffin, light liquid paraffin and mixture of light paraffin, and petroleum ether (1:1 v/v ratio). Microspheres prepared in highly viscous castor oil exhibited an average size of 11.52 ± 0.57 µm with a percentage drug entrapment of 43.12 ± 2.14. On the other hand, very small microspheres of 3.15 ± 0.04 µm and 68.87 ± 1.03% drug entrapment were obtained when mixture of liquid paraffin and petroleum ether was utilized as oil phase. Effect of viscosity on percent mucoadhesion, percent drug entrapment, zeta potential, percent process yield, etc. of microspheres has been observed. In vitro drug release in phosphate buffer pH 7.4 was determined for different batch of microspheres. The results revealed a difference in the drug release pattern of the different microspheres prepared as a function of viscosity of different oil phase. Use of low viscose oil resulted in the formulation of spherical and small size microspheres. This work was a part of our ongoing thrust and project to develop microparticulate drug delivery system