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Updated: Aug 10, 2026
Generation of Alginate Microspheres for Biomedical Applications
Published on: August 12, 2012
Controlled-release preparation of indomethacin using calcium alginate gel
S Shiraishi1, T Imai, M Otagiri
1Faculty of Pharmaceutical Sciences, Kumamoto University, Japan.
Insights
Alginate gel beads offer controlled release of indomethacin (IMC), showing prolonged absorption and sustained therapeutic levels in dogs and humans. This formulation enhances indomethacin
Area of Science:
- Pharmaceutical Sciences
- Biomaterials Science
- Drug Delivery Systems
Background:
- Indomethacin (IMC) is a nonsteroidal anti-inflammatory drug with a short half-life, necessitating frequent dosing.
- Controlled-release formulations aim to improve therapeutic efficacy and patient compliance.
- Alginate, a natural polysaccharide, has shown potential for developing drug delivery systems.
Purpose of the Study:
- To develop and evaluate alginate gel beads as a controlled-release formulation for indomethacin (IMC).
- To investigate the effect of alginate properties on IMC release kinetics.
- To assess the pharmacokinetic profile of IMC delivered via alginate beads in animal models and human volunteers.
Main Methods:
- Alginate gel beads containing IMC were prepared using calcium-mediated gelation.
- In vitro release studies were conducted at different pH values (1.2 and 6.8).
- The influence of alginate composition (M/G ratio) and molecular weight on release was examined.
- Pharmacokinetic studies were performed in beagle dogs and human volunteers following oral administration of beads and IMC powder.
Main Results:
- IMC release was negligible at pH 1.2 but occurred at pH 6.8 due to alginate swelling.
- Reduced IMC release was observed with lower M/G ratios and higher alginate molecular weights.
- Oral administration of alginate beads resulted in lower peak plasma concentrations but prolonged and sustained absorption of IMC compared to IMC powder.
- Effective serum concentrations of IMC were maintained for up to 12 hours in human volunteers after administration of alginate beads.
Conclusions:
- Alginate gel beads provide a viable strategy for the controlled release of indomethacin.
- Alginate properties, including M/G ratio and molecular weight, significantly influence drug release.
- The developed formulation demonstrates potential for improving the therapeutic management of conditions requiring sustained indomethacin levels.
Abstract:
Alginate gel beads containing indomethacin (IMC) were prepared using a gelation of alginate with calcium cation. Though IMC was not released from the beads at pH 1.2 because of its extremely low solubility in aqueous media, it was released according to the swelling of alginate gel at pH 6.8. The release of IMC from the beads decreased with the decreasing ratio of mannuronic acid (M) to guluronic acid (G) in alginate, and with the larger molecular weight of alginate. The maximum concentration and the area under the time curve of plasma concentration of IMC after oral administration of alginate gel beads to beagle dogs were lower than those of IMC powder. The absorption rate of IMC was lower and more prolonged after administration of beads containing IMC than IMC powder alone. The high plasma concentration of IMC was maintained because absorption continued for a longer period when the bead consisting of the alginate with 0.65 M-block/G-block ratio and 66000 molecular weight was administered. The availability of alginate gel beads of IMC was further demonstrated by oral administration to human volunteers. A serum concentration which was comparable to maximum serum concentration was maintained from 2 to 6 h after administration, while an effective serum concentration was maintained even 12 h after administration of the beads. These data suggest that alginate is useful for a controlled-release formulation of IMC.
