A pharmaceutical study on a drug in topical delivery systems / Rana Mohamed Gebreel ; Supervised Mohamed Ahmed Elnabarawi , Mina Ibrahim Tadros , Doaa Hussien Hassan

Thesis (Ph.D.) - Cairo University - Faculty of Pharmacy - Department of Pharmaceutics

Poor ophthalmic bioavailability of drugs ({u02C2}1%) from common eye drops occurs mostly due to the precorneal loss factors like the quick tear turnover, the non-productive drug absorption, the momentary residence time in the cul-de-sac, and the poor drug permeability to the corneal epithelial membrane. The limited ocular bioavailability of drugs favors the need for frequent instillation to accomplish the targeted therapeutic effect, which may lead to undesirable side effects as a result of systemic drug absorption. The efficiency of an ophthalmic drug delivery system depends on the drug bioavailability, which could be enhanced by extending the pre-corneal drug residence time and promoting corneal drug penetration.Keratitis is an ocular disease that can result from microbial infection (eg, bacteria, fungi, viruses, or protozoans) or from non-infectious damage,such as that caused by eye trauma or exposure to chemicals or ultraviolet light.Microbial keratitis is considered a sight-threatening infection that can cause ulceration of the cornea and produce scarring, neovascularization, and loss of vision in severe cases. Poor patient compliance is usually encountered with microbial keratitis since a frequent instillation schedule every 2{u2013}4 hrs is needed for common infections and every 30 min for extreme corneal ulcers. Upon ocular instillation, the drug solution or suspension mixes with the lacrimal fluid and remains in contact with the mucosa for 1{u2013}2 minutes only due to the continuous release of lacrimal fluid. Furthermore, the drainage through the lower and the upper canaliculus into the lacrimal sac and then to the nasolacrimal duct would induce a rapid drug loss during blinking. The ocular drug bioavailability could be enhanced by altering the physicochemical characteristics of the drug and/or the development of specific nano-delivery systems

Issued also as CD