The term
microcapsule
[MS] is defined as a spherical particle with size varying
from 50 nm to 2 mm and containing a core substance. Microspheres, in a strict sense,
are spherical empty particles. However, the terms
microcapsules
and
microspheres
are
often used synonymously. In addition, some related terms are used. For example,
mi-
crobeads
and
beads
are used alternatively. Spheres and spherical particles are also used
for a large size and rigid morphology. It is well known that, since the introduction of
microcapsules by Green et al. in the 1950s [139], the preparation, characterization, and
applications of microcapsules and microspheres have been reviewed widely [140–148].
Due to attractive properties and wider applications of chitosan-based microcapsules and
microspheres, a survey of the applications in CDR formulations is appropriate. Moreover,
microcapsule and microsphere forms have an edge over other forms in handling and
administration. Therefore, up-to-date information on chitosan microcapsules and micro-
spheres is presented here