Biodegradable polyesters for veterinary drug delivery systems: Characterization, in vitro degradation and release behavior of Oligolactides and Polytartrate
In Hinblick auf die Entwicklung von innovativen pharmazeutischen Veterinärprodukten wurde im Rahmen dieser Arbeit der Abbau- und Freisetztungs-mechanismus von aliphatischen Polyestern experimentell untersucht. Der erste Komplex der vorliegenden Arbeit befaßte sich mit dem Einfluß...
Saved in:
| Main Author: | |
|---|---|
| Contributors: | |
| Format: | Doctoral Thesis |
| Language: | English |
| Published: |
Philipps-Universität Marburg
2003
|
| Subjects: | |
| Online Access: | PDF Full Text |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Table of Contents:
This thesis deals with the degradation and
release behavior of aliphatic polyesters with special respect
to the influence of oligomers on the degradation rate and the
potential use of these biomaterials for the development of
veterinary drug delivery systems. In Chapter 1 the animal
health care market is introduced with regard to opportunities
and challenges of veterinary drug delivery systems. . In the
second part of this chapter biodegradable polymers used for
veterinary applications are discussed with emphesis on their
degradation and release properties. Current applications of
biodegradable drug delivery systems in the field of
reproduction control, growth promotion, vaccination and control
of ectoparasites are summarized. Chapter 2 describes the
synthesis and characterization of a homologous series of low
molecular weight poly(D,L-lactides). The oligomers were
analyzed using SEC, DSC and 1H-NMR to obtain information about
their physico-chemical properties as function of average chain
length. The interest was focused on the determination of the
critical molecular weight for water solubility of oligomers. In
addition the hydrolysis kinetic of oligomer degradation and the
mechanism of ester cleavage was investigated in vitro. The
effect of low molecular weight poly(D,L-lactides) on the
degradation process of PLGA is reported in Chapter 3. PLGA
films containing oligomers of different molecular weight in
various amounts were prepared by a solvent casting technique
and the degradation was monitored by SEC, WAXD, DSC and
gravimetric methods. Chapter 4 describes the characterization
and in vitro degradation of Poly(2,3-(1.4-diethyl
tartrate)-co-2,3-isopropyliden tartrate). In Chapter 5 the
influence of the degradation behavior on in vitro drug release
from PTA implants is described. Effects of drug loading and
implant size on release profile were studied in more detail.
Chapter 6 describes the in vivo release properties of buserelin
implants in dogs. By using model-independent methods such as
statistical moment analysis and model-dependent methods
(curve-fitting) the in vitro release profiles were compared to
the in vivo performance. An attempt was made to develop
different levels of in vitro-in vivo correlation for
biodegradable implants.