Preparation of biodegradable microspheres and matrix devices containing naltrexone |
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Authors: | Rassoul Dinarvand Shadi H Moghadam Leyla Mohammadyari-Fard Fatemeh Atyabi |
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Institution: | (1) Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran |
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Abstract: | In this study, the use of biodegradable polymers for microencapsulation of naltrexone using solvent evaporation technique
is investigated. The use of naltrexone microspheres for the preparation of matrix devices is also studied. For this purpose,
poly(L-lactide) (PLA) microspheres containing naltrexone prepared by solvent evaporation technique were compressed at temperatures
above the Tg of the polymer. The effect of different process parameters, such as drug/polymer ratio and stirring rate during
preparation of microspheres, on the morphology, size distribution, and in vitro drug release of microspheres was studied.
As expected, stirring rate influenced particle size distribution of microspheres and hence drug release profiles. By increasing
the stirring speed from 400 to 1200 rpm, the mean diameter of microspheres decreased from 251 μm to 104 μm. The drug release
rate from smaller microspheres was faster than from larger microspheres. However, drug release from microspheres with low
drug content (20% wt/wt) was not affected by the particle size of microspheres. Increasing the drug content of microspheres
from 20% to 50% wt/wt led to significantly faster drug release from microspheres. It was also shown that drug release from
matrix devices prepared by compression of naltrexone microspheres is much slower than that of microspheres. No burst release
was observed with matrix devices. Applying higher compression force, when compressing microspheres to produce tablets, resulted
in lower drug release from matrix devices. The results suggest that by regulating different variables, desired release profiles
of naltrexone can be achieved using a PLA microparticulate system or matrix devices. |
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Keywords: | microspheres matrix devices naltrexone poly(L-lactide) solvent evaporation |
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