Investigation of Drug Release and 1H-Nmr Analysis of the in Situ Forming Systems Based on Poly(Lactide-Co-Glycolide) Publisher



Mohamadnia Z¹ ; Ahmadi E^{1, 2} ; Rafieni M³ ; Mirzadeh H^{1, 3} ; Mobedi H¹ Show Affiliations
Source: Polymers for Advanced Technologies Published:2009

Abstract

In situ forming biodegradable polymeric systems loaded with betamethasone (BTM) and betamethasone acetate (BTMA) were prepared using poly(DL-lactide-co-glycolide) (PLGA), ethyl heptanoate (EH), and N-methyl-2-pyrrolidone (NMP) as the biodegradable polymer, additive, and solvent, respectively. The drug release studies were carried out in buffer (pH = 7.4, 37°C) using high performance liquid chromatography (HPLC). 1H-NMR was used to determine the polymer degradation behavior, release mechanism, and interactions between the polymer and drug. The 1H-NMR spectra showed that all interactions between the polymer and drug were hydrogen bonding. Hydroxyl groups and fluorine in drugs were involved in hydrogen bonding with PLGA polymer. In 1H-NMR studies, we found that the degradation rate in the systems loaded with BTMA was higher than the systems loaded with BTM because BTMA is only slightly soluble and accelerates the hydrolysis of PLGA chains. The formulations loaded with BTM had obviously lower burst release compared with BTMA loaded samples. With respect to 1H-NMR spectra, the mechanism of BTM release is controlled by two effective factors: solvent removal and polymer degradation. Copyright © 2008 John Wiley & Sons, Ltd.