Niosomes inocular dug delivery system:Ocular drug delivery system facinghigh challenging due to the distinctive physiology and anatomy of eye whichcontaining different barriers like many layers of sclera, cornea and retina inaddition to lachrymal fluid, blood retinal, eye barrier and drug that loss fromthe ocular surface. To overcome those obstacles, thevesicular drug delivery systems especially Niosomes are preferred intransporting the drug through the eye due to high stability and their abilityto enhance drug absorption by modifying the permeability of the scleral andconjunctival membranes of ophthalmic region. They provide increase the durationof action by inhibition of ocular metabolism in the lachrymal fluid.
Niosomesare used in wide range in the treatment of allergy, inflammation, ocularhypertension, dry eye and glaucoma. Furthermore, it has the advantage ofadministration of the drug in form of a drop that offer significant progressionin increasing the pre-ocular retention on the eye surface and enhancement oftrans-corneal penetration of novel therapeutic agents.Niosomes should have specificattributes in relation to their use. In the ocular drug delivery system,niosomes should have some characteristics as:· Thevesicular size of the niosomes should be large to resist the drainage by theeye blinking and the reflex tearing.· Thelarger mulilameller vesicle are present in the ocular surface larger time thansmall unilameller niosomes. In addition the larger the vesicle, the largeramount of the drug encapsulated in it.· Niosomeswhich contain tween 20 is significantly improve the bioavailability of manydrugs.
· Theyshould be thermo-responsive to control the drug release and time manner beforeflushed· Theshape of niosomes should have some irregularities to fit in the cul-de-disk ofthe eye and bdge on the eye surface.