Novel approach of
OPTHALMIC DRUG DELIVERy
Under the Esteemed Guidance of
Department of Pharmaceutics
ANATOMY OF EYE
BARRIERS FOR OCULAR DDS
TYPES OF OCULAR DDS
GENERAL SAFETY CONCERNS
ADVANCES IN OCULAR DDS
Traditionally used eye drop formulations lacked good
bioavailability and had low patient compliance, hence
most investigations in this field emphasize on the
duration of action and enhancement of corneal
Recent developments in ophthalmic drug delivery
systems include use of gelling polymers, prodrugs,
microspheres, nanoparticles, liposomes and
hydrophilic ocular inserts. Protein and peptide
delivery, posterior drug delivery and non-aqueous
vehicles are new areas of interest in ophthalmic drug
• The Ophthalmic Drug Delivery Systems (ODDS)
are desired to improve efficacy, minimization of
toxicity, sustained effect or modified drug release.
• Cyclodextrin cyclic oligosaccharides are the
newer carriers in ODDS which have proved to be
useful for controlled release by forming a
complex which is known to show rapid and
quantitative drug release.
RELEVANT ANATOMY AND
PHYSIOLOGY OF THE EYE
• HUMAN EYE : The accessory structures of the
eye are the eyelids, eyelashes, eyebrows, the lachrymal
apparatus and extrinsic eye muscles. The diameter of
eye is 23mm.
BARRIERS FOR OCULAR DELIVERY
Drug loss from the ocular surface after instillation, the flow
of lacrimal fluid removes instilled compounds from the
surface of the eye.
Even though the lacrimal turnover rate is only about 1
μl/min the excess volume of the instilled fluid is flown to
the nasolacrimal duct rapidly in a couple of minutes.
Another source of non-productive drug removal is its
systemic absorption instead of ocular absorption.
Systemic absorption may take place either directly from the
conjunctival sac via local blood capillaries or after the
solution flow to the nasal cavity.
Approaches to improve ocular
1) Viscosity enhancers 8) Eye ointments
2) Gel 9) Prodrug
3) Penetration enhancers 10) Liposomes
4) Niosomes 11) Nanosuspension
7) In situ-forming gel
Classification Of Ophthalmic
1)Based on route of administration:
b)Intra ocular solution
2)Based on physical form:
TYPES OF OCULAR DRUG DELIVERY
2)Soluble ocular drug inserts(sodi)
Role Of Polymer In ODDS
Solution Viscosity , Solution Drainage. Polymer
Mucoadhesive Vehicle: Retained in the eye due to non-
covalent bonding between with conjuctival mucine. Mucine
is capable of picking of 40-80 times of weight of water
Polymeric Solution: The addition of polymers like
methylcellulose, polyvinyl alcohol, hydroxypropyl cellulose
and polyvinyl pyrrolidone to the eye drop solution increases
the corneal penetrations of drug.
• This is presumably due to on increases tear viscosity, which
decreases the other wise rapid initial drainage rate, increases
the corneal contact time and thus sustains to some extant the
initial tear concentration of the drug.
LIMITATIONS OF CONVENTIONAL
Rapid precorneal elimination
Solution drainage by gravity
Frequent instillation is necessary
Sustained and/or controlled drug release
Protect the drug from chemical or
Increasing contact time and thus
Better patient compliance.
Advances in Ophthalmic Drug
IN-SITU GELS -A NOVEL APPROACH FOR OCULAR DRUG
• Polymeric gels for improved drug
• Ophthalmic inserts :are defined as sterile
solid or semisolid preparations, with a thin, flexible and
multilayered structure, for insertion in the conjunctival sac.
Iontophoresis is the process in which direct current
drives ions into cells or tissues .
Evaluation of ocular drug delivery
Ocular drug delivery systems are evaluated by
various methods. The ocular in-vitro studies include
design of specialised apparatus.
The ocular in-vivo studies were done in rabbits and
include tear pH measurements, pharmacodynamic
studies and scintigraphy to assess precorneal
residence of formulations.
In-vitro evaluation methods :
A number of approaches are used by different
workers to conduct in-vitro evaluation of controlled
ocular drug delivery systems.
(a) Bottle method
(b) Diffusion method
(c) Modified rotating basket method
(d) Modified rotating paddle apparatus
(e) Flow through devices
(2) In – vivo evaluation methods
The controlled ocular drug delivery systems can be
evaluated for its pharmacokinetic and pharmacodynamic
The main objective of the pharmacokinetic studies is to
determine the drug release from the dosage form to the eye.
Rabbit is used as an experimental animal because of a
number of anatomical and physiological ocular similarities
and also due to larger size of the eye .
Glucotim LA of Centaur Pharma is an original research
formulation of Timolol .Used to treat Glaucoma.
Combigan contains brimonidine. Combigan is used to
treat glaucoma or ocular hypertension
In the past 2 decades, a considerable amount of
research has been carried out on the development
of ocular drug delivery systems.
It is appreciated that the topical route is preferred
for delivery of drugs to the eye.
The primary objective of all the ocular drug
delivery systems developed till date is to increase
ocular drug residence time which leads to
improvement in ocular drug bioavailability,
diminish side effects due to systemic absorption
and diminishing the necessary amount of drug for
a therapeutic response in the eye.
1.Hill J M, O' Callaghan R J, Hobden J A, Kaufman H E. Corneal
Collagen shields for ocular delivery. In :Mitra A K, eds. Ophthalmic
drug delivery systems, New York: Marcel Dekker Inc., 1993; 261 – 273.
2.Hughes P M, Mitra A K. Overview of ocular drug delivery and
iatrogenic ocular cytopathologies. In : Mitra A K, eds. Ophthalmic drug
delivery systems, New York: Marcel Dekker Inc., 1993; 1-28.
3.Van Ootegham M. M M. Fomulation of ophthalmic solutions and
suspensions. In : Edman P, eds. Biopharmaceutics of ocular drug
delivery, Boca Raton : CRC press, 1993; 27-42.
4.Mueller W H, Deardroff D L. Ophthalmic vehicles: The effect of
methyl cellulose on the penetration of Homatropine hydrobromide
through the cornea. J. Am. Pharm. Assoc. 1956; 45: 334.
5.Krishna N, Brown F. Polyvinyl alcohol as an ophthalmic vehicle. Am.
J. Ophthalmol. 1964; 57: 99.
6.Swanson AA, Jeter D J, Tucker P. Ophthalmic vehicles II.
Comparison of ointment and polyvinyl alcohol 1.4% . Ophthalmologica.
1970; 160: 265 - 270.