Effects of microwave on drug-release responses of spray-dried alginate microspheres.

CONTEXT

Microspheres prepared from rigid guluronic acid- (MG) and flexible mannuronic acid-rich (MC) alginate will undergo different drug release changes with respect to the influence of microwave on the matrix. An in-depth understanding of their differences in drug release changes is attainable through investigating cross-linking agent-free alginate microspheres prepared by spray-drying technique.

OBJECTIVE

The behavior of MG and MC alginate in controlling drug release responses of spray-dried microspheres against microwave was investigated. Sodium diclofenac was used as a model water-soluble drug. The formed microspheres were subjected to drug release, drug content, size, shape, surface morphology, Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffractometry analysis.

RESULTS

MC microspheres required a shorter period of microwave irradiation to reduce drug release extent than MG microspheres. In response to microwave, the drug release profiles of 1:1 MG-MC microspheres resembled MC microspheres.

DISCUSSION

The state of polymer-polymer and drug-polymer interaction via O-H and/or N-H moiety of microspheres was affected by alginate chain flexibility under the influence of microwave. It then governed the drug release responses of microspheres.

CONCLUSION

The drug release property of alginate microspheres can be modified by microwave irradiation, and its changes are a function of alginate conformation.