Article Sidebar
Article Details
Submission of a manuscript to this journal is a representation that the manuscript has not been published previously and is not under consideration for publication elsewhere.
All authors named in each manuscript would be required to sign a form (to be supplied by the Editor) so that they may retain their copyright in the article but to assign to us (the Publishers) and its licensees in perpetuity, in all forms, formats and media (whether known or created in the future) to (i) publish, reproduce, distribute, display and store the contribution, (ii) translate the contribution into other languages, create adaptations, reprints, include within collections and create summaries, extracts and/or abstracts of the contribution, (iii) create any other derivative works(s) based on the contribution, (iv) to exploit all subsidiary rights in the contribution, (v) the inclusion of electronic links from the contribution to third party material where-ever it may be located, and (vi) license any thrid party to do any or all of the above.
Main Article Content
Parameters to be Considered in the Simulation of Drug Release from Aspirin Crystals and their Microcapsules
Abstract
Method: Four single crystals of aspirin of varied weight and orthorhombic in shape or their microcapsules also of varied weights were randomly selected for the study. The microcapsules were walled with an acrylatemethacrylate copolymer (wall thickness, 11 m). The following parameters were evaluated: the order of release, the dissolution rate constant, k (crystals), the diffusion coefficient, D (microcapsules), the maximum release m and time to attain it t. These parameters were in turn used to simulate the release profiles of hypothetical single particles of a wide range size distribution, 0.3 1.4 mm at 0.1mm intervals.
Results: The empirical single crystals exhibited an initial zero order (93%; dissolution constant = 4.4 min-1) followed by a first order release (6%; dissolution constant = 0.38 min-1). Maximum release from each of the crystals was 99% of the initial particle weight; thus m was a constant fraction of the initial particle weight. A zero order release consistent with a Fickian diffusion model was displayed by the single microcapsules (diffusion coefficient, 5.4x10-4 mm2min-1). At same particle weight the release parameters m, t, and the slopes of the rate order plots compared favourably with the theoretical data.
Conclusion: The study indicates that the empirical release data on a few single particles can be used to predict the release profiles of single particles of a wide range of size distribution. This finding may be exploited in the prediction of drug release from polydisperse systems.
Keywords: Aspirin crystals, drug release, simulation, microcapsules
Tropical Journal of Pharmaceutical Research 2002; 1(2): 99-110
