Ocular drug Delivery System

Name: Md. Abul HossainID NO: PG12-11-15-020

Ocular Drug Delivery System ?Classifications of ocular drug delivery systems:These can be classified on the basis of their physical forms as follows: Liquids: Solutions, Suspensions, Sol to gel systems, Sprays Solids: Ocular inserts, Contact lenses, corneal shield, Artificial tear

inserts, Filter paper strips. Semi-solids: Ointments, Gels Miscellaneous: Ocular iontophoresis, Vesicular systems,

Mucoadhesive dosage forms, Particulates, Ocular penetration.

The mechanism of controlled drug release into the eye.

1.Diffusion: In the Diffusion mechanism, the drug is released continuously at a

controlled rate through the membrane into the tear fluid2.Osmosis: In the Osmosis mechanism, the insert comprises a transverse

impermeable elastic membrane dividing the interior of the insert into a first compartment and a second compartment.

3.Bio-erosion: In the Bioerosion mechanism, the configuration of the body of the

insert is constituted from a matrix of bioerodible material in which the drug is dispersed.

Formulation of ocular Drug

Routes of Administration into the Eye Topical administration1.Eye drops:

Drops may be in solution form (clear - e.g.anaesthetic drops) or in suspension (cloudy - e.g. Steroids).

2.Eye ointments:

They help lubrication so that concurrent lubricant use is not always necessary (unless there was previous intensive usage or there is a large abrasion).

Physiology of Eyes

Sclera,-tough sheath around eyeball Choroids,absorbs unused light Outer-Epithelium(lipophilic), Inner-Endothelium(lipophilic). Cornea,refracts light into eye Cilliary BodySecretion of aq. humor, Lens,-flexible unit Retina,-screen where image is formed Conjuctiva,layer of eye Vitreous Compartment, Pupil-aperture through which light enters

Advantage and Disadvantage Advantage:

1.Increased accurate dosing.

2.To overcome the side effects of pulsed dosing produced by conventional delivery. Disadvantage:

1.The very short time the solution stays at the eye surface.

2.Its poor bioavailability.

3.The necessity of using preservative.

Research and development studies

Research: Many attempts have been made to develop practical approaches to the

modified delivery of drugs to the eye. Development: The first developed bodies contained gentamicin sulphate, an aminosidic

antibiotic, as a model drug. Most ophthalmic drugs contain alcohol, phenol, carboxylic acids and amines

that lend themselves to derivatization. The modification of chemical structure of drug centres on changing

physiochemical properties of drugs such as lipophilicity, solubility and pKa.

Design and DevelopmentThe design requirements for the proposed drug delivery device are as follows: target overall volume is less than 280 mm. diffusion rate is less than 0.07 L/min. target diffusion time period will be around 1 to 2 years. kinetics: reliable diffusion coefficient of drugs through the

microchannels. implantable: eliminate repeated injections for effective treatment. actuation: sustained release drug delivery methods.

Dosage Forms Applied to the Eye Solutions Suspensions Ointments Gels Emulsions Strips Injections Contact Lenses

Conclusion

Ocular drug delivery systems provide local as well as systemic delivery of the drugs. The novel advanced delivery systems offer more protective and effective means of the therapy for the nearly inaccessible diseases or syndrome of eyes. Further development are preferable which will eliminate the corns of these available advanced delivery systems and readily acceptable with the regulatory authorities as well.

Thanks to all