21-07-2012, 01:43 PM
OCULAR DRUG DELIVERY
[attachment=28343]
INRODUCTION:
Ocular drug delivery systems are developed to treat eye locally, whereas past formulations are targeted to reach systemic circulation and these are designed to overcome all the disadvantages of conventional dosage forms such as ophthalmic solutions [1]. The main problem with conventional dosage forms is eye irritation (due to drug particle size and shape) which induces lacrimation i.e. overflow on to lids, tear turn over, and due to pharmacokinetic responses like metabolism, non-specific binding and different mechanisms like diffusion, dissolution and erosion the conventional dosage forms are less advantageous [2] .
PHYSIOLOGY OF EYE:
The eye consists of transparent cornea, lens, and vitreous body without blood vessels. The oxygen and nutrients are transported to this non-vascular tissue by aqueous humor which is having high oxygen and same osmotic pressure as blood. The aqueous humor in human is having volume of 300 μl that fills the anterior chamber of the eye which is in front of lens.
OCULAR DRUG DELIVERY SYSTEMS:
The necessary characters of Ideal control release ocular drug delivery system are: It should not induce a foreign-body sensation or long lasting blurring. It should possess more local activity than systemic-effects. It must deliver the drug to the right place, i.e. in targeting the ciliary body. It should be easy to self-administer.
Non-erodible ocular insert:
The Non-erodible ocular inserts include Ocusert, and Contact lens. Ocusert was one of the earlier ocular inserts in use. The technology used in this is an insoluble delicate sandwich technology [13]. In ocusert the drug reservoir is a thin disc of pilocarpine-alginate complex sandwiched between two transparent discs of micro porous membrane fabricated from ethylene-vinyl acetate copolymer [15]. The micro porous membranes permit the tear fluid to penetrate into the drug reservoir compartment to dissolve drug from the complex.
[attachment=28343]
INRODUCTION:
Ocular drug delivery systems are developed to treat eye locally, whereas past formulations are targeted to reach systemic circulation and these are designed to overcome all the disadvantages of conventional dosage forms such as ophthalmic solutions [1]. The main problem with conventional dosage forms is eye irritation (due to drug particle size and shape) which induces lacrimation i.e. overflow on to lids, tear turn over, and due to pharmacokinetic responses like metabolism, non-specific binding and different mechanisms like diffusion, dissolution and erosion the conventional dosage forms are less advantageous [2] .
PHYSIOLOGY OF EYE:
The eye consists of transparent cornea, lens, and vitreous body without blood vessels. The oxygen and nutrients are transported to this non-vascular tissue by aqueous humor which is having high oxygen and same osmotic pressure as blood. The aqueous humor in human is having volume of 300 μl that fills the anterior chamber of the eye which is in front of lens.
OCULAR DRUG DELIVERY SYSTEMS:
The necessary characters of Ideal control release ocular drug delivery system are: It should not induce a foreign-body sensation or long lasting blurring. It should possess more local activity than systemic-effects. It must deliver the drug to the right place, i.e. in targeting the ciliary body. It should be easy to self-administer.
Non-erodible ocular insert:
The Non-erodible ocular inserts include Ocusert, and Contact lens. Ocusert was one of the earlier ocular inserts in use. The technology used in this is an insoluble delicate sandwich technology [13]. In ocusert the drug reservoir is a thin disc of pilocarpine-alginate complex sandwiched between two transparent discs of micro porous membrane fabricated from ethylene-vinyl acetate copolymer [15]. The micro porous membranes permit the tear fluid to penetrate into the drug reservoir compartment to dissolve drug from the complex.