Bioabbaubare Polymernetzwerke mit Formgedächtniseffekt als Matrix für Wirkstofffreisetzungssysteme
This thesis describes the development and characterization of matrix systems based on biodegradable polymer networks with shape-memory properties for controlled delivery of low molecular mass drugs. A polymer network based on oligo[(e-hydroxycaproate)-co-glycolate]dimethacrylates and butylacrylate with a semi-crystalline switching segment is used for the systematic investigation of the influence of the polymer matrix on drug release. A direct comparison with copoly(esterurethane)networks of oligo[(rac-lactate)-co-glycolate]tetrols and diisocyanate as polymer matrices gives information about the influence of the type of crosslinkings on drug release. In addition, copoly(esterurethane) networks of oligo[(e-hydroxycaproate)-co-glycolate]tetrols and diisocyanate with an amorphous switching segment are evaluated. The antimicrobial drugs ethacridin lactate, nitrofurantoin and enoxacin are incorporated into the polymer matrix by swelling the polymer networks in a solution of the drug, followed by a quantitative displacement of the solvent. The drug loading of the materials varies between 0,1 mass-% and 2,4 mass-%, depending on the swelling degree of the polymer networks, the solubility of the drugs in the polymer matrix, and the solvent. Additionally, ethacridin lactate is incorporated into the polymer networks by homogenous dispersion in the oligo[(e-hydroxycaproate)-co-glycolate]dimethacrylates, followed by photochemical crosslinking in situ. A drug concentration in the polymer matrix ranging between 0,2 mass-% and 5,7 mass-% is achieved by this loading technique. The thermal, mechanical and shape memory properties of drug loaded polymer networks, with a maximum drug content of 4,8 mass-%, agree well with those of the unloaded materials, independent of the drug loading technique. Polymer networks loaded by dispersion of ethacridin lactate show a diffusion controlled drug release, without the occurrence of a burst-effect. An increasing glycolate content and a reduction of crystallinity accelerate the permeation of ethacridin lactate and, accordingly, increase the drug release. The influence of the matrix deformation and the shape memory effect on drug release of polymer networks with a transition temperature, Ttrans, below and above 37 °C is investigated. For polymer networks with Ttrans > 37 °C an external, thermal stimulus is used.
info:eu-repo/classification/ddc/540, Chemie, bioabbaubar, Polymer, kontrollierte Wirkstofffreisetzung
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