Preparation and evaluation of micro-porous ethylcellulose capsule as oral sustained-release preparation of theophylline

Abstract

Micro‐porous ethylcellulose (EC) membrane capsules were prepared by dissolving polyvinylalcohol (PVA) particles from membranes which were made of a mixture of EC (a water‐insoluble polymer). The pore size was approximately 400 μm. Since the dissolution rate of theophylline from the micro‐porous EC membrane capsules was fast, gel‐forming polymer, poly(acyclic) acid (Carbomer), was incorporated inside the capsule at 10, 20 or 30 mg. Using test capsules containing 100 μm of theophylline, in vitro dissolution studies were performed. By including Carbomer in capsule formulations, the dissolution rate of theophylline was decreased. However, there were not significant differences in dissolution rates between preparations containing the three different amounts of Carbomer. In vivo evaluation studies using beagle dogs showed that AUC, Cmax and Tmax were inversely proportional to the formulated amount of Carbomer. The capsule containing 20 mg of Carbomer gave plasma theophylline concentrations between 5 and 15 μg mL−1, which reflect levels within the therapeutic window. The effect of food intake on the pharmacokinetics of theophylline was also studied with the same capsule. Food increased AUC, Cmax and Tmax, although plasma theophylline levels were maintained within the therapeutic range. © 1998 John Wiley & Sons, Ltd.

Polymerization of Electric Field-Centered Double Emulsion Droplets to Create Polyacrylate Shells

“…Hollow and porous particles ranging from nanometers to millimeters in diameter comprise an important class of materials that are used in a wide variety of applications. For example, metal and polymer shells in the nanometer-to-micrometer size range are used as sensors, , drug delivery vehicles, − catalysts, , thermal insulators, , and opacifying and acoustic absorption agents. − Hollow polymer particles that are hundreds of micrometers to several millimeters in diameter are used in foods, for drug encapsulation, , and as cryogenic capsules for laser fusion experiments. − To create hollow particles with new or tailored physical and chemical properties, the particle size, shape, thickness, porosity, surface topology, and composition need to be controlled. In some applications, control over the shell thickness uniformity (concentricity) and particle roundness (sphericity) is especially important.…”