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Increasing the Bioavailability of Eye Drops Essay

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Most ocular diseases are treated with topical application of eye drops. After instillation of an eye drop, typically less than 5% of the applied drug penetrates the cornea and reaches intraocular tissues, while a major fraction of the instilled dose is absorbed and enters the systemic circulation. As ocular efficiency of topically applied drugs is influenced by the corneal contact time, most common method of improving ocular availability of drugs is to increase pre-corneal residence time by using vesicular system and hydrogel. One such approach to improve bioavailability of drug is the use of in-situ gelling system, which gets converted from sol-to-gel as a result of change in pH. By using Carbopol940 – a pH sensitive gelling agent, an…show more content…
A significant challenge to the formulator is to bypass the protective barriers of the eye without causing permanent tissue damage.
Conventional ophthalmic formulations like solution, suspension, and ointment have many disadvantages which result in poor bioavailability of drug in the ocular cavity. The specific aim of designing a therapeutic system is to achieve an optimal concentration of a drug at the active site for the appropriate duration [3]. The various approaches that have been attempted to increase the bioavailability and the duration of the therapeutic action of ocular drugs can be divided into two categories. The first one is based on the use of sustained drug delivery systems such as vesicles and particulates, which provide the controlled and continuous delivery of ophthalmic drugs. The second involves maximizing corneal drug absorption and minimizing pre-corneal drug loss which can be achieved by amphiphilic vesicles [4].
Niosomes are non-ionic surfactant vesicles obtained by hydration of synthetic nonionic surfactants, with or without incorporation of cholesterol or other lipids. They are vesicular systems similar to liposomes that can be used as carriers of amphiphilic and lipophilic drugs [5]. Niosomes are promising vehicle for drug delivery and being non-ionic; they are less toxic and improve the therapeutic index of drug by restricting their action to target
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