پديد آورندگان :
Bahmanyar Nargess نويسنده , Haghbeen Kamahldin نويسنده , Jamshidi Ahmad نويسنده , Evini Mina نويسنده , Mobedi Hamid نويسنده , Mobedi Elham نويسنده
چكيده لاتين :
Structural stability of the entrapped leuprolide acetate (LPA) in poly(DL-lactide-coglycolide)
(PLGA) was studied after in-vitro release of the drug using UV-Vis,
fluorescence , circular dichroism , 1HNMR spectroscopic and HPTLC techniques .
To prepare the injectable implant, 3% (v/v) of LPA was dissolved in a mixture of 33%
(v/v) of PLGA (intrinsic viscosity of 0.5 dUg) in N-methyl-2-pyrrolidone (NMP) as solvent.
Upon introduction of 1 g of the above mixture (containing 30 mg of LPA) into 4 mL
of aqueous carbonate buffer at pH 7.2, NMP diffuses out from the matrix causing the
polymer to precipitate . Release of the drug into 4 mL of the fresh buffer solution at 37°C
was measured every 24 h for one month. The UV-Vis and intrinsic fluorescence spectra
of the solutions were recorded right after collection. Then, the release media were
lyophilized and studied by 1H NMR spectroscopy. Although a clear interpretation of the
CD spectra was faced to some ambiguities, the first derivative of the UV-Vis spectra
and the results of fluorescence studies indicated that the tertiary structure of the peptide
had suffered litlie destruction during its stay in PLGA. 1H NMR studies of the
released medicine showed no change in the peptide primary structure . HPTLC analysis
of the release medium showed one band with similar Rf to the original sample of
LPA. The collected results indicate that the entrapped LPA suffers no structural
changes during its stay in polymer formulation and remains stable during the first 24 h
of release .
