Ocuserts are solid or semisolid ocular inserts designed for ophthalmic drug delivery. They deliver drugs at a constant rate via diffusion and increase corneal contact time to prolong drug effects. This improves bioavailability and reduces dosing frequency. Ocuserts consist of a central drug reservoir, rate-controlling membrane, and outer ring. They are classified as insoluble, soluble, or bioerodible inserts depending on their composition. Insoluble inserts include diffusional and osmotic inserts that control drug release via membranes. Soluble inserts are natural or synthetic polymers that diffuse drug. Bioerodible inserts modulate drug release during erosion.

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

2.  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. 1. Insoluble ocular inserts : a. Diffusional inserts
b. Osmotic inserts
c. Hydrophilic contact
lenses
2. Soluble ocular inserts : a. Natural polymeric inserts
b. Synthetic insert
3. 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
a) Natural polymeric inserts : collagen type
b) 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 Ocuserts
• 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 Ocuserts
• 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