الفهرس 
Factors affecting oral bioavailability
Permeation enhancers loaded bilosomes for improved intestinal absorption and cytotoxic activity of doxorubicinOnly 14 pages are availabe for public view
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Abstract
Oral route is the most appropriate route for administration of drugs. Unfortunately, poor oral bioavailability made it difficult for many appreciated drugs to be delivered through oral route of administration. The reasons of poor oral bioavailability include poor solubility, slow dissolution, poor membrane permeability, extensive pre-systemic metabolism, degradation in the gastrointestinal tract or intestinal efflux via P-glycoprotin. Therefore alternative techniques have been employed to overcome poor membrane permeability. These include the use of permeation enhancers. This strategy showed high potential even with macromolecules. Numerous compounds have been employed as penetration enhancers. These include traditional surfactants, bile salts, bacterial toxins, chelating agents, medium and long chain fatty acids. These materials have been shown to enhance the absorption of poorly permeable drugs. The problem may be aggravated if poor permeability is associated with other problems like poor dissolution and/or extensive first pass metabolism. In this case combined strategies may be necessary to enhance the bioavailability. Incorporation of the penetration enhancers into specific colloidal carrier can provide promising strategy. Colloidal carriers comprise liposomes, niosomes, bilosomes, solid lipid nanoparticles, self microemulsifying drug delivery systems, micellar systems, etc. However, the feasibility of such technique requires verification. Therefore the main objective of this thesis was to investigate the potential of colloidal systems to improve oral bioavailability of class III and IV drugs.