The O/W emulsion method has been widely used for the production of poly (lactide-co-glycolide) (PLGA) microparticles. Recently, a template method has been used to make homogeneous microparticles with predefined size and shape, and shown to be useful in encapsulating different types of active compounds.
tPolymeric microparticles have been used widely for sustained drug delivery. Current methods ofmicroparticle production can be improved by making homogeneous particles in size and shape, increas-ing the drug loading, and controlling the initial burst release. In the current study, the hydrogel templatemethod was used to produce homogeneous poly(lactide-co-glycolide) (PLGA) microparticles and toexamine formulation and process-related parameters.
A new microencapsulation technique that utilizes interfacial mass transfer between two mutually soluble liquids has been developed. The technique is based on formation of a solid polymer film at the interface of a solution of a water-insoluble polymer and an aqueous solution, resulting from the mutual mass transfer of solvents (i.e., solvent exchange).
The important factors in developing biodegradable microparticles for protein drug delivery are protein release profile (including burst release, duration of release, and extent of release), microparticle size, protein loading, encapsulation efficiency, and bioactivity of the released protein.
Reservoir-type microcapsules were produced in a mild and highly efficient manner using a coaxial ultrasonic atomizer. To understand the microencapsulation mechanism, the atomizer was operated in different modes. The results suggested the reservoir-type microcapsules were formed by midair collision of the microdrops of the two component liquids consisting of a polymer solution and an aqueous solution.
The hydrogel template method was used to fabricate homogeneous drug–PLGA microparticles. Four drugs (felodipine, risperidone, progesterone, and paclitaxel) were loaded into the PLGA particles with the homogeneous size of 10 μm, 20 μm, and 50 μm. The drug loading into the PLGA microparticles was 50% and higher.
Microencapsulated particles have become indispensable in controlled drug release systems. Biocompatible microparticles with modifi ed drug release profi les are particularly useful for the development of parenteral formulations. Examples of useful types of modifi ed release profi les include:
The hydrogel template method allowed preparation of homogeneous particles with predefined sizes with high drug loading. It allowed study on the effect of size and shape on the drug release kinetics. With the microparticles of homogeneous size and shape, the drug release kinetics can be projected based on the size of microparticles and water-solubility of a drug. The ability of making homogeneous particles is expected to provide better prediction and reproducibility of the drug release property of a given formulation.
The MiCE microencapsulation process allows effective monitoring and control of the instrumental parameters affecting microcapsule production. However, the microcapsule collection method in this process needs to be further optimized to obtain microcapsules with desired morphologies, precise membrane thicknesses, high encapsulation efficiencies, and tight size distributions.