This work involves an investigation into the feasibility of using polyamide microcapsules as a basis for the treatment of glaucoma. The Introduction considers conventional treatment of glaucoma together with novel ophthalmic drug delivery systems. Various methods by which microcapsules may be prepared are discussed and the preparation of polyamide microcapsules is discussed in detail. The properties of polyamides are described together with the properties of polyamide microcapsules. Consideration is also given to the theoretical release from microcapsules. The Materials and Methods section lists the materials and instrumentation used throughout this work and describes the general methods used. The Experimental section describes the development and preparation of nylon 6.10 and polyphthalamide microcapsules. This is followed by details of their properties including appearance, size distribution and release of encapsulated pilocarpine nitrate. Methods by which the preparation conditions were then modified are considered. These involve the addition of gelatin to the core, the use of short chain crosslinking molecules and the preparation of double walled microcapsules. The properties of these modified microcapsules are described. This section is followed by details of the structure of the microcapsule walls together with measurements of the permeability of polyphthalamide films. The final section of the experimental work discusses in vivo studies concerning the effect of microencapsulated pilocarpine nitrate on the rabbit eye and the dwell time of polyphthalamide microcapsules in the eye. The final section of this thesis deals with the discussion of the experimental results obtained. The main conclusion drawn is that the walls of the polyphthalamide microcapsules do not significantly control the release of pilocarpine nitrate from the microcapsule core. This may arise due to the presence of pores in the microcapsule walls. Attempts to modify or reduce the release rate characteristics of the microcapsules by modification of the core and wall were unsuccessful.
|Date of Award||1983|