Abstract :
This work it puts in the context of the synthesis of a
biodegradable polymer derived from renewable resources such as corn, and its
application in biomedical area, particularly as drug carriers. Three
poly(D,L-lactic acid) polymers with different molecular weights (1000, 3000 and
9000) g/mol were synthesized by a method of azeotropic condensation
polymerization of D,L-lactic acid at 140°C under vacuum with using a
catalyst (SnCl2). Molecular weights of PDLLAs were determined by a viscosimeter
(Ubbelhode).
Thereafter, PDLLA/ibuprofen (IB) mixtures were prepared using
three methods of preparation such as physical mixes, hot mixes and solvent
evaporation methods. For each mixture, three formulations (F5, F15 et F25) were
prepared. All the formulations contain the same quantity of IB (20 mg) but they
differ from the quantity of PDLLA loaded 5% (F5), 15% (F15) et 25% (F25).
The crude compounds (PDLLA, IB) as well as the different
formulation were characterized by using several characterization physical
methods as FTIR, XRD, SEM and DSC. We noted that, once the particles of IB are
mixed with those of PDLLA, size and morphology of particles were altered.
Moreover, FTIR methods revealed that the absorption band in the region of
carbonyl of ibuprofen was shifted towards the higher frequencies (í),
once IB is mixed with PDLLA. Indeed, interactions with hydrogen with hydrogen
bonding were supposed to be existing between IB and PDLLA. The X-ray
diffraction revealed that the spectrum of ibuprofen undergo certain changes
such as widening of the width, increase height, and shift of the peaks.
The results of in vitro dissolution showed that the rate
release of ibuprofen was modified in all the formulations. Ibuprofen was
released in fast way at the first stage, followed by slow release (or
quick/slow profile). The rate release of the IB decreases when the quantity and
the molecular weights of PDLLA increases. The release kinetics of IB is faster
in an alkaline medium of dissolution (pH 7.4) that in an acidic one (pH 5.8).
The release kinetics of ibuprofen also slows down according to the method of
preparation in the order : hot mix, physical mix and solvent evaporation
mix.
Keywords: Poly(D,L-lactic acid)
(PDLLA), Ibuprofen, Biodegradable polymers, drug carriers, physical mixes, hot
mixes, solvent evaporation methods.
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