2-Hydroxyethyl Methacrylate Hydrogels for Local Drug Delivery: Study of Topotecan and Vincristine Sorption/Desorption Kinetics and Polymer-Drug Interaction by ATR-FTIR Spectroscopy
Abstract
Poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogels are well known in ophthalmological applications and recently investigated as drug delivery systems. The study represents a theoretical approach where the sorption/desorption experiments and spectroscopic study is used to describe the influence of the pHEMA network structure on the sorption capacity and mechanism of the release of topotecan (TPT) and vincristine (VCR).
The hydrogels are synthesized by free-radical crosslinking polymerization of HEMA monomer with ethylene glycol dimethacrylate as a crosslinker in the concentration range from 0.3 to 1 wt%. Experimental data from sorption kinetics are evaluated using sorption kinetic models and sorption isotherms, drug release mechanism is assessed by two different models and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy is employed to describe the polymer-drug interaction. pHEMA hydrogels exhibit higher affinity for TPT than for VCR and hydrogels prepared with 0.5 wt% of crosslinker show the maximum sorption capacity for both drugs.
Physisorption is proved to be the sorption mechanism. Analyzing the FTIR spectra, it is concluded that the hydrophobic crosslinks play an important role in the interaction of the hydrogel backbone with molecules of both drugs.