Ocular controlled drug delivery system

In the area of topical ocular administration, important efforts concern the design and the conception of new ophthalmic drug delivery systems able to prolong the residence time.

1. Ocular controlled drug delivery system PRESENTED BY:- DEBASISH SAHOO M. PHARM 1 ST YEAR DEPARTMENT OF PHARMACEUTICS ISF COLLEGE OF PHARMACY, MOGA, PUNJAB

2. INTRODUCTION The ophthalmic preparations are available as sterile, buffered, isotonic solution. Suspensions, gelled systems, ointment are also used for prolonged therapeutic action. Prolonged drug release can be achieved using ophthalmic inserts, solid devices placed in the eye, but the inserts must then be removed when they are no longer needed. Ocuserts release the drug at predetermined and predictable rates thus eliminating the frequent administration of the drug. The elements generally include an inner layer, or core, including a therapeutic agent, and one or more outer layers made of polymeric materials, for example substantially pure polymeric materials. In the area of topical ocular administration, important efforts concern the design and the conception of new ophthalmic drug delivery systems able to prolong the residence time.

3. ANATOMY OF EYE ROUTES

4. IDEAL CHARACTERSTICS OF OCDDS Delivery the drug to the right place, i.e. high conjunctival levels are useless when targeting the ciliary body. Increase ocular bioavailability of drug by increasing corneal contact time. Reduce the number of administrations per day, once a day considered the optimal goal. Easy to self administer. Not induce a foreign body sensation, long-lasting blurring or a bad aftertaste. Circumvent the protective barriers like drainage, lacrimation and diversion of exogenous chemicals into the systemic circulation by the conjunctiva.

5. MECHANISM OF CONTROL DRUG RELEASE INTO THE EYE The mechanism of controlled drug release into the eye is as follows:

6. DRUG IN TEAR FLUID OCULAR ABSORPTION CORNEAL ROUTE Primary route Small, lipophilic drug CONJUNCTIVAL AND SCLERAL ROUTE Large, Hydrophilic drugs AQUEOUS HUMOR SYSTEMIC ABSORPTION (~ 50-100% of dose) Major routes: Conjunctiva of eye Nose Minor routes: Lacrimal drainage system Pharynx GIT Skin at cheek lids Aqueous humor Inner ocular tissues OCULAR TISSUE ELIMINATION Fig:-Factors and corneal barrier limitations for penetration of topically admistered drug

7. Various approaches in cr ocular dds Polymeric solution Phase transition system Mucoadhesive/ bioadhesive dosage forms Collagen shields Pseudolatices Ocular penetration enhancers Ocular iontophoresis Ocular drug delivery devices

8. 1.Polymeric solutions Polymer used-methylcellulose, polyvinyl alcohol, poly vinyl pyrrolidone. Increases the corneal penetrations of drug. Increase tear viscosity, corneal contact time and decreases rapid initial drainage rate. 2.Phase transition system Liquid dosage forms which shift to gel or solid phase when instilled in the cul -de sac. Polymer used- A) Lutrol FC-127 and Poloxamer 407 viscosity increases when its temperature raised to 37ºC B) CAP coagulates when its native PH of 4.5 is raised by tear fluid to PH 7.4

9. 3.Mucoadhesive/ bioadhesive dosages Polymer solution adheres to the mucin at the cornea and conjunctival surface. interaction called mucoadhesion increasing contact time 4.Collagen shields Cross linking of collagen corneal shield increase ofloxacin bioavailability. But there is some drawback. 5.Pseudolatices Polymeric colloidal dispersion film forming agents used for topical application. 6.Ocular penetration enhancers Enhancer like actin filament inhibitors, surfactants, bile salts, chelators and organic compound are used to increase bioavailability. 7.Ocular iontophoresis Direct current devices ions into cells or tissue.

10. 8.Ocular drug delivery devices These solid devices are intended to be placed in the conjunctival sac and to deliver the drug at a comparatively slow rate. Two types of ocular inserts:-

11. Ocusert:- Technology used-insoluble delicate sandwich technology. Drug reservoir is a thin disc of pilocarpine-alginate complex sandwiched between two transparent discs of microporous membrane fabricated from ethylene-vinyl acetate copolymer. Microporous membrane permit the tear fluid to penetrate into the drug reservoir compartment to dissolve drug from the complex. E.g-Alza-ocusert: In this pilocarpine molecules are released at constant rate of 20 or 40µg/hr for 4 to 7 days. Used in the management of glaucoma Contact lense :- Pre-soaked hydrophilic contact lenses is used for ophthalmic drug delivery. Therapeutic soft lenses are used to aid corneal wound healing in patient with infections, corneal ulcers.

12. Lacrisert:- Lacrisert is a cylindrical device, which is made of cellulose and used to treat dry eye patient. Retention time is long (2 weeks or more).

13. SODI(Soluble ocular drug insert) It is a thin film of oval shape made from acrylamide, N-vinyl pyrrolidone and ethyl acrylate. Wt. about 15-16 mg. Inserted into the inferior cul-de-sac and get wets and softens in 10-15 seconds. After 10-15 min the film turns into a viscous polymer mass, after 30-60 min it turns into polymer solutions and delivers the drug for about 24 hrs. Minidisc Consists of a disc with a convex front and concave back surface in the contact with the eye ball. Like miniature contact lenses with a diameter of 4-5mm.The minidisc is made up of silicone based prepolymer α -omega-bis (4-methacryloxy) butyl poly-di-methyl siloxane.