ocuserts [ocular inserts]

ocular inserts or ocuserts in ocular drug delivery system

1. Ocuserts By G. Tarun Kumar 10201S0301 1 st year M. Pharmacy [pharmaceutics] Bapatla college of pharmacy

2. Ocuserts Ocuserts [ocular inserts] are defined as sterile preparations , multilayered, solid or semisolid devices placed in cul-de-sac or conjunctival sac and whose size and shape are designed especially for ophthalmic application Deliveres at constant rate by diffusion mechanism Ocuserts increase corneal contact time , prolongs duration of action , improve bioavailability , reduces the frequency of administration and thus acheive patient compliance Ocusert ® , pilocarpine ocular therapeutic system is the firstproduct by Alza incorporationUSA from this catogary Generally all types of ocuserts consist of 3 components namely : 1.A central drug reservoir 2.Rate controlling membrane 3.An outer annular ring meant for easy handling

3. Classification of ocular inserts Insoluble ocular inserts : a. Diffusional inserts b. Osmotic inserts c. Hydrophilic contact lenses Soluble ocular inserts : a. Natural polymeric inserts b. Synthetic insert Bio erodable inserts : a. Soluble ocular drug inserts [SODI] b. Lacrisert c. Minidiscs d. Collagen shields

4. Type 1 Type 2 Central part is composed of single reservoir of drug with osmotic solute dispersed throughout a polymeric matrix The peripheral part comprise a covering film made of an insoluble semi permeable membrane The osmotic pressure against the polymer matrix causes its rupture form apertures from where drug releases Central part is composed of two distinct compartments , the drug and osmotic solute in two separate compartments Drug reservoir is surrounded by elastic impermeable membrane and osmotic layer is by semi permeable membrane Osmotic pressure that stretches the elastic membrane and contracts the compartments , so drug release from aperture 1. Insoluble ocular inserts a. Diffusional inserts The release of drug from the inserts is based on diffusional release mechanism Drug release is controlled by the lachrymal fluid permeating through the membrane and when sufficient internal pressure was developed , then only drug comes out of the reservoir b. Osmotic inserts The osmotic inserts consist of a central part surrounded by a peripheral part and are of two types

5. C. Hydrophilic contact lenses These are covalently cross linked hydrophilic or hydrophobic polymers that forms a 3 dimensional matrix capable of retaining water , aqueous solution or solid components Provide extended release of drugs into the eye There are two types of contact lenses : Hard contact lenses and Soft contact lences Soft lenses are used to aid corneal wound healing in patients with infections and corneal ulcers . They treat corneal erosions and epithelial defects after corneal transplantation 2 . Soluble ocular inserts Soluble inserts offer the advantage of being entirely soluble so that they need not to be removed from their site of application Simple design and easily processed by conventional methods Controlled by diffusion mechanism Natural polymeric inserts : collagen type Synthetic polymeric inserts : cellulose derivatives

6. 3. Bio erodible ocular inserts These are formed by bio erodible polymers Ex. Cross linked gelatin derivatives , polyester derivatives They can modulate their erosion rate by modifying the final structure during synthesis and by addition of anionic or cationic surfactants A. Soluble ophthalmic drug insert [SODI] It is a small oval wafer developed by soviet scientists for cosmonauts who could not use eye drops in weightless conditions It is a thin film made from acrylamide , N- vinylpyrrolidone and ethylacrylate B. Lacrisert Sterile rod shaped device made of HPC without any preservatives Weight is 5mg , diameter 12.7mm , length 3.5mm Used in treatment of keratitis , inserted into inferior fornix by a special applicator Imbibes water from cornea and conjunctiva , forms hydrophilic film which stabilizes the tear film and hydrates and lubricates the cornea .

7. C. Minidiscs Minidiscs are profiled , convex outside , concave from the side of contact with eye surface , d is 4-5 mm which are similar to contact lenses Main copolymers are ᾳ - ῳ - bis [4-methacryloxy]-butyl poly[ dimethylsiloxane ] and poly [ hydroxyethyl methacylate ] This dosage form is either hydrophilic or hydrophobic which enables extended time period of release of water soluble and poorly soluble drugs D. Collagen shield Collagen is the structural protein of bones , tendons , ligaments and skin and comprises more than 25% of total body protein in mammals Produces higher drug concentration in cornea and aqueous humour when compared with eye drops and contact lenses Collagen shields are fabricated with foetal calf skin tissue and originally developed as a corneal bandage

8. Adavntages of O cuserts Increased ocular residence, hence prolonged drug activity and higher bioavailability Releasing drugs at slow and constant rate Accurate dosing Reduction of systemic absorption Better patient compliance , targeting internal ocular tissues through conjunctival and scleral routes Disadvantages of O cuserts A capital disadvantage of ocular inserts is their solidity which results in inconvenience in patients Unwanted migration of inserts to upper fornix Interference with vision Difficult in placement of ocular inserts