This document provides an overview of ocular drug delivery systems (ODDS). It discusses the advantages and disadvantages of ODDS, ideal characteristics, formulations, classifications like Ocuserts, barriers to ocular absorption, evaluation methods, and reasons for poor bioavailability. Ocuserts are described as elliptical drug delivery devices that continuously release drugs like pilocarpine for 7 days when placed in the eye. Barriers to absorption include the cornea, conjunctiva, sclera, aqueous humor, and retinal barriers. Evaluation methods covered include thickness, drug content, weight variation tests, moisture absorption tests, in vitro diffusion tests, in vivo studies in animals, and accelerated stability studies.

1. 1
Presented By-
Akshay bhama
M.Pharma 1st sem
DEPARTMENT OF PHARMACEUTICALS SCIENCE
H.N.B.GARHWAL UNIVERSITY, SRINAGAR

2. CONTENTS
2
 INTRODUCTION
 ADVANTAGE AND DISADVANTAGE
 IDEAL CHARACTERISTICS OF ODDS
 FORMULATION
 CLASSIFICATION
 OCUSERTS
 GENERAL PATHWAY OF OCULAR DRUGS
 BARRIERS IN OCULAR ABSORBANCE
 EVALUATION OF OCULAR POLYMERIC FILMS
 CONCLUSION
 REFERENCE

3. 3
 Ocular administration of drug is primarily associated with the
need to treat ophthalmic diseases.
 DEFINATION:- They are specialized dosage forms designed
to be instilled into the external surface of the eye(topical),
administered inside (intraocular) or adjacent (periocular) to the
eye or used in conjunction with an ophthalmic device.
 Eye is the most easily accessible site for topical administration
of a medication.
 Ideal ophthalmic drug delivery must be able to sustain the drug
release and to remain in the contact of the eye for prolong
period of time.
INTRODUCTION

4. 4
 Administration is easy.
 Provide quick absorption and
effect.
 Increased shelf life due to
absence of water.
 Better Patient compliance.
 There is very short time the
soln. stays at the eye surface.
 It’s poor bioavailability.
 The stability of the dissolved
drug.
 The necessity of using
preservative.
 Interference with vision.
 Loss of drug during sleep or
while rubbing eyes.
ADVANTAGE DISADVANTAGE

5. IDEAL CHARACTERISTICS OF DOSAGES
FORM:
 Sterility
 Isotonicity- (0.5 – 2 % Nacl)
 Surface activity- must have good wetting ability so it can penetrate the
cornea.
 Buffer/pH adjustment- 7.4 pH
 Less drainage tendency
 Stabilized
5

6. Formulation
 Drug- Active pharmaceutical ingredient.Antiseptic, Anti-inflammatory agent,etc
 Preservative- Chlorbutanol, Phenylmercuric acetate, Phenylmeruric
nitrate,etc.
 Sterilization- Autoclaving, filteration through bacteria proof filters.
 Isotonicity- Boric acid , sodium and phosphate buffer are added
 Buffer- Monobasic Sodium, Boric Acid.
 Viscosity -Polysorbate 80, Benzalponium chloride , etc are added.
 Additives-
Thickening agent- Methy Cellulose
Antioxidants- Ascorbic Acid
Inert Gases- to deplace oxygen
Chelating agents- Trisodium or calcium disodium
Antimicrobial- Phenol, Benzyl Alcohol
Wetting agent- Egg yolk, Glycerin
Suspending agents- Gelatin, Pectin
Stabilizers- Glycerin, Creatinine
 Container
 Label 6

7. 7

8. Ocuserts
8
 The Ocusert therapeutic system is a flat, flexible , elliptical device designed to
be placed in the inferior cul-de-sac between the sclera and the eyelid and to
release Pilocarpine continuously at a steady rate for 7 days.
 They act by imbibing water from the cornea and conjunctiva and form a
hydrophilic film which lubricates the cornea.

9.  The device consists of 3 layers-
i. Outer layer- ethylene vinyl acetate copolymer layer.
ii. Inner Core – Pilocarpine gelled with alginate main polymer.
iii. A retaining ring- of EVA impregnated with titanium di oxide . A
annular ring that make it visible.
The ocuserts availabe in 2 forms:
 Pilo-20 : - 20 mg/hr.
 Pilo-40 :- 40 mg/hr.
9

10. 10
 Reduced local side
effects and toxicity.
 Around the clock
control of IOP.
 Improved
compliance.
 Increased in shelf
life due to absence
of water.
 Retention in the eye
for the full 7 days.
 Periodical check of
unit.
 Replacement of
contaminated unit
 Expensive.
 Movement around
the eye.
ADVANTAGE DISADVANTAGE

11. General Pathway Of Ocular Drugs
11

12. BARRIERS IN OCULAR ABSORBANCE
1. Anatomical barriers
When a dosage form is topically administered there are 2 routes of
entry :-
a. The cornea is a very tight multilayered tissue that is mainly composed
of five sections: epithelium, bowman’s membrane, stroma, descemet’s
membrane and endothelium.
b. Non-corneal route bypasses the cornea and involves movement
across conjunctiva and sclera. This route is important especially for
large and hydrophilic molecules such as peptides, proteins and siRNA.
2. Physiological barriers
The eye’s primary line of defense is its tear film. Bioavailability of
topically administered drugs is further reduced by precorneal factors
such as solution drainage, tear dilution, tear turnover, and increased
lacrimation.
12

13. Anatomical barrier:-
13
a) Corneal barrier
 Anatomy of Cornea
 Outer-Epithelium(lipophilic)
 Middle-Stroma(hydrophilic)
 Inner-Endothelium(lipophilic)

14.  Moderately charged molecules pass through cornea.
 Tight junctions of 5-6 layers of columnar epithelial cells limits hydrophilic molecules.
 Charged stromal layer allow hydrophilic drugs to easily pass through but limits the
passage of lipophilic molecules (it act as sieve for molecules).
 The remaining layers are leaky and do not act as significant barriers.
 Constant flow of a tear film across the outer surface of the cornea limits diffusion and
limited capacity of the lacrimal lake result in a low bioavailability.
14

15. b) Non-corneal route
i) Scleral barrier
 Barrier to diffusion of macromolecules.
 Permeability decreases at high molecular weight.
 This is region from where variety of molecules are able to penetrate.
15

16.  Poses tight junctions that prevent easy penetration of the molecules.
 Intercellular spaces wider than the cornea and therefore more permeable to
larger molecules.
 Presence of blood and lymphatic vessels thus drug molecules absorbed across the
conjunctiva taken up by into the systemic circulation. Only a small fraction of the dose
reaches the vitreous.
16
ii) Conjunctival barrier

17. Aqueous humor-
 Aqueous humor protected by blood-aqueous barrier. Made up of non pigmented
epithelium layer of cilliary bodies.
 This barrier allows active and paracellular transport controlled by tight junctions.
 Fluorescently labeled dextrans as large as 150 kDa are able to cross the
barrier.
17

18. Retinal barrier
 Diffusion barrier to macromolecular
 Diffusion of drugs with molecular weight more than 76kDa is
limited.
 The inner and outer plexform layers provides highest
resistance to the diffusion of macromolecules.
 Macromolecules larger than 150 kDa were arrested at inner
limiting membrane of the retina.
 The blood retinal barrier separates the neurosensoryretina
from the systemic circulation.
 Inner retinal barrier composed of the tight junctions b/w the
endothelium of the retinal vasculature.
 The outer bleed retinal comprises of the retinal pigment
epithelium with tight junctions posing significant barriers to
macromolecules.
18

19. EVALUATION OF OCULAR POLYMERIC
FILMS
 THICKNESS OF THE FILM
Measured by dial caliper at different points and the mean value is
calculated.
 DRUG CONTENT UNIFORMITY
The cast film cut at different places and tested for drug as per
monograph.
 UNIFORMITY OF WEIGHT
The weight variation test is done by weighing three patches cut
from different places of the same formulation and their individual
weights are determined by using the digital balance. Next, their mean
value is calculated. The standard deviation of weight variation is
computed from the mean value.
19

20.  PERCENTAGE MOISTURE ABSORPTION
Here ocular films are weighed and placed in a dessicator containing 100 ml
of saturated soln. of aluminium chloride and 79.5% humidity was maintained.
After three days the ocular films are reweighed and the % moisture
absorbed by :-
% moisture absorbed=(Final weight- intial weight) × 100
Initial weight
20

21. IN- VITRO EVALUATION METHODS
 BOTTLE METHOD
In this, dosage forms are placed in the bottle containing dissolution medium
maintained at specified temp. and pH.
Then bottle is shaken.
A sample of medium is taken out at appropriate intervals and analyzed for
the drug content.
21
• DIFFUSION METHOD
– Drug solution is placed in the donor compartment and
buffer medium is placed in between donor and receptor
compartment.
– Drug diffused in receptor compartment is measured at
various time intervals.

22. IN-VIVO STUDY
 Here, the dosage form is applied to one eye of animals and the other
eye serves as control.
 Then the dosage form is removed carefully at regular time interval
and are analyzed for drug content.
 The drug remaining is subtracted from the initial drug content, which
will give the amount of the drug absorbed in the eye of animal at
particular time.
 After one week of washed period, the experiment was repeated for
two time as before.
22

23. ACCELERATED STABILITY STUDIES
 These are carried out to predict the breakdown that may occur over
prolonged periods of storage at normal shelf condition.
 Here, the dosage form is kept at elevated temp. or humidity or
intensity of light, or oxygen.
 Then after regular intervals of time sample is taken and analyzed for
drug content.
 From these results, graphical data treatment is plotted and shelf life
and expiry are determined.
23

24. Reason to have poor bioavailability
of ODDS due to :-
 Conjunctival absorption.
 Rapid solution drainage by gravity.
 Induced lachrymation and Naso lacrimal drainage.
 Blinking reflex.
 Low corneal permeability.
 Normal tear turn over as tear dilute it.
 Interaction of drug with lacrimal fluid.
24

25. CONCLUSION
 All approaches improve ocular drug bioavailability by increasing
ocular drug residence time, diminish side effects due to systemic
absorption and diminishing the necessary therapeutic amount of drug
for therapeutic response in anterior chamber.
 They improve patient compliance by reducing the frequency of
dosing.
 They reduce the dose and other by reduce the adverse effects of the
drug.
25

26. REFERENCES
 N.K. Jain, Advances in Controlled & Novel Drug
Delivery, CBS Publication, & distributor, New Delhi,
 Remington & Gennaro; The Science & Practice Of
Pharmacy. Mack Publication Company. Easton,
Pennsylvania.
 Kaur IP, Garg A, Singla AK, Aggarwal D. Vesicular
systems in ocular drug delivery: an overview.Int J
Pharm. 2004.
 Jounal of Advanced Pharmaceutical Technology &
Research
 Modern dispensing pharmacy: N.K. Jain
 Dispensing for pharmaceutical by Cooper and gunn’s.
26

27. 27
Thank You