Porous pellets as drug delivery system.

BACKGROUND: Multiparticulate drug delivery systems, such as pellets, are frequently used as they offer therapeutic advantages over single-unit dosage forms. AIM: Development of porous pellets followed by evaluation of potential drug loading techniques. METHOD: Porous microcrystalline pellets were manufactured and evaluated as drug delivery system. Pellets consisting of Avicel PH 101 and NaCl (70%, w/w) were prepared by extrusion/spheronization. The NaCl fraction was extracted with water and after drying porous pellets were obtained (33.2% porosity). Immersion of the porous pellets in a 15% and 30% (w/v) metoprolol tartrate solution, ibuprofen impregnation via supercritical fluids and paracetamol layering via fluidized bed coating were evaluated as drug loading techniques. RESULTS: Raman spectroscopy revealed that immersion of the pellets in a drug solution and supercritical fluid impregnation allowed the drug to penetrate into the porous structure of the pellets. The amount of drug incorporated depended on the solubility of the drug in the solvent (water or supercritical CO(2)). Drug release from the porous pellets was immediate and primarily controlled by pure diffusion. CONCLUSION: The technique described in this research work is suitable for the production of porous pellets. Drug loading via immersion the pellets in a drug solution and supercritical fluid impregnation resulted in a drug deposition in the entire pellet in contrast to fluid bed layering where drugs were only deposed on the pellet surface.

Controlled release of drugs from multi-component biomaterials.

In order to control their release, drugs are encapsulated into systems which are expected to provide a certain site with a predetermined amount of drug over a well-defined period of time. Here we report on a multi-component drug delivery biomaterial that consists of a hydrogel matrix in which drug-loaded biodegradable microcarriers are dispersed, and whose potential applications could be found in the design of implantable devices with long-term activity, as required by contraceptive and hormone replacement treatments. The release profile of the drug can actually be tuned by the complex interplay of several release mechanisms, including the permeability and eventually the degradation rate of the microcarriers and the diffusion through the hydrogel. The hydrogel consisted of 2-hydroxyethyl methacrylate cross-linked by ethylene glycol dimethacrylate. The microcarriers were biodegradable poly-epsilon-caprolactone (PCL) microspheres in which active molecules, such as levonorgestrel (LNG), were encapsulated. The hydrogels were characterized by water swelling, thermal properties, LNG diffusion through drug-free and drug-depleted hydrogel membranes and LNG release from devices with drug dispersed in the hydrogel. The PCL microspheres were observed by scanning electron microscopy; their size distribution, LNG loading and release were also investigated. The hydrogel-microsphere assemblies were characterized in terms of the distribution of the microspheres within the hydrogel, water swelling and the release of the encapsulated molecules. The developed device, due to its composite structure, has the ability to combine several release mechanisms, leading to drug release obeying zero-order kinetics for most of the time.