Diffusional release from salt-walled microcapsules

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" Diffusional release from salt-walled microcapsules "
A. V. Kulkarni T. J. Speaker

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1112684
Doc. No	:	TLpq303948075
Main Entry	:	A. V. Kulkarni
	:	T. J. Speaker
Title & Author	:	Diffusional release from salt-walled microcapsules\ A. V. KulkarniT. J. Speaker
College	:	Temple University
Date	:	1991
student score	:	1991
Degree	:	Ph.D.
Page No	:	296
Abstract	:	A microencapsulation technique involving interfacial reaction of nonaqueous solutions of salts of organic bases emulsified in aqueous solutions of salts of weakly acidic macromolecules was developed at Temple University. As part of the characterization of these microparticles it was desirable to describe a technique, and determine the mathematical model(s), which would describe the rates at which encapsulated active and/or adjuvant materials might be released when the microcapsules were employed as sustained release dosage forms. "Temple technology" was used to prepare charged-film microcapsules containing the first four members of the series of n-alkyl esters of para-aminobenzoic acid (PABA). Purified arabic acid and anhydrous piperazine, selected as wall-forming reagents, were carried into the two phases of an emulsion by water and methylene chloride respectively. Stoichiometric equivalences of the wall forming reagents were determined and used in phase-ratio studies to establish the suitability of the selected reaction and carrier reagents. The microcapsules were prepared by emulsification, concentration and lyophilization; suitable batches containing the PABA esters, possessing minimum differences in their physical properties were prepared. For size distribution analysis, a unique computer program was developed. The program transformed particle size data obtained from a Coulter Counter apparatus to forms suitable for statistical analysis. Of particular use was the log-probability transform of Gaussian data. Size-distribution analysis of prepared microcapsules aided the selection of batches and the calculation of surface area terms. Measurement of release rates was achieved by a continuous flow dialysis system. The experimental results were found to be consistent with a Fickian model, and inconsistent with a Higuchi model, for describing the release of analyte from microcapsules. The parameters studied were lag time (lT), effective permeability coefficient (P), diffusion coefficient (D) and the contributory factors--initial concentration (CO) and surface area (A).
Subject	:	Health and environmental sciences
	:	microcapsules
	:	Pharmaceuticals