Bj. Lee et al., PREPARATION AND CHARACTERIZATION OF MELATONIN-LOADED STEARYL ALCOHOL MICROSPHERES, Journal of microencapsulation, 15(6), 1998, pp. 775-787
Citations number
20
Categorie Soggetti
Pharmacology & Pharmacy","Chemistry Applied","Engineering, Chemical
A sustained release dosage form which delivers melatonin (MT), a pinea
l hormone, is of clinical value because of the short half-life of MT,
for those who have a disordered circadian rhythm. The purpose of this
study was to prepare MT-loaded microspheres by the emulsion melting/co
oling method using stearyl alcohol (SA) and also dual walled chitosan
and sodium alginate beads, and to evaluate the release characteristics
in simulated gastric and intestinal fluid. The MT-loaded microspheres
were spherical, ranging in diameter from about 250-750 mu m. When pol
yethylene glycol 4000 (PEG), as a water-soluble or aluminium tristeara
te (AT), as a water-insoluble additive, was incorporated, the surface
roughness was further reduced resulting in a smooth matrix structure.
The dual walled chitosan and sodium alginate beads entrapping small MT
-loaded microspheres were not spherical in structure. As the additives
incorporated into SA microspheres increased, the drug content decreas
ed. The release profiles of the MT-loaded microspheres were independen
t of pH. When the melted SA solution was cooled rapidly in 10 min to 2
5 degrees C, the drug content increased but the release rate of MT-loa
ded microspheres decreased. The release rate of drug decreased as the
amount of SA increased but an increase of agitation speed and amount o
f AT and PEG resulted in increased release rates. The release rate of
drug from dual walled chitosan beads increased slightly but was retard
ed in the case of dual walled alginate beads when compared to MT-loade
d microspheres. The emulsion melting/cooling method used to prepare MT
-loaded microspheres using SA is simple and inexpensive, and may provi
de an alternative for the preparation of an oral sustained release dos
age form of MT without using harmful organic solvents. The dual walled
chitosan and sodium alginate beads may also provide a convenient way
to control the release of drugs.