The mucoadhesive microparticles (CHCNZ) composed of chitosan (CH) and cinnarizine (CNZ) hydrochloride
were successfully prepared, in a process of solution-enhanced dispersion, by supercritical CO2 (SEDS) technique. Scanning
electron microscopy was used to reveal the morphological characteristics of mucoadhesive microparticles. The average
particle size of microparticles was in the range from 1.9 to 12.8 µm. In vitro and in vivo mucoadhesive tests showed
that CHCNZ mucoadhesive microparticles adhered more strongly to gastric mucous layer. Thereby retaining in gastrointestinal
tract for an extended period of time and exhibiting good mucoadhesive properties. The X-ray powder diffractometry
and differential scanning calorimetry analysis demonstrated that the SEDS process was an efficient physical coating
process to produce CHCNZ composite microparticles. It also suggests that CNZ did not undergo chemical changes during
the production of microparticles. The optimized batch exhibited a high drug entrapment efficiency of 67 % with particle
size of 3.9 µm. A sustained pattern of drug release was obtained for more than 20 h. In vivo studies were carried out by
administering orally cinnarizine HCl (CNZ) suspension and mucoadhesive microparticles to rabbits under fasted (for 12
h) conditions. The results showed that CNZ mucoadhesive microparticles had a better bioavailability than CNZ suspension
due to longer retention in the gastric environment of the test animals.
Keywords: Cinnarizine HCl, microparticles, supercritical CO2, mucoadhesion, chitosan.
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