2. ________
INTRODUCTION
Millions of people worldwide suffers from several eye
diseases which threaten sight, as glaucoma, cataract,
diabetic retinopathy and dry eyes.
The defense mechanisms observed in the eye (epithelium,
tear flow and blinking reflex) hamper the drug penetration
into deeper layers of the eye.
The previously mentioned diseases with those challenges
forced researchers to develop new techniques in drug
3. ________
WHAT IS LIPOSOME?
Liposome is a hollow
nanosphere composed of
lipid bilayers (phospholipids,
lipid conjugated polymers,
and cholesterol) that can
entrap both lipophilic and
hydrophilic drug
molecules.
4. ________
LIPOSOMES VS MICELLES
Liposomes are composed of lipid bilayers separating an
aqueous internal compartment from the bulk aqueous
phase, while micelles are closed lipid monolayers with a
fatty acid core and polar surface.
Liposomes are formed mainly by phospholipid molecules
such as cholesterol, while micelles are formed by surfactant
molecules such as detergents or emulsifiers.
Liposom Micell
5.
6. ________
CHARACTERISTICS OF LIPOSOMES
Bilayer structure: amphiphilic molecules, typically
phospholipids, which have a hydrophilic head and
hydrophobic tail. The structure allows them to encapsulate
hydrophilic and hydrophobic substances.
Biocompatibility: safe for use in biological systems. They
are well-tolerated by the body and have low toxicity.
Versatility: They can encapsulate a wide range of drugs,
molecules, and compounds. They are suitable for delivering
7. ________
…CHARACTERISTICS OF LIPOSOMES
Controlled release: can be designed to provide controlled
and sustained drug release. This can improve the
therapeutic effect and reduce the frequent dosing.
Targeted delivery: Surface modifications can be made to
liposomes to enhance their specificity for particular cells,
tissues, or organs.
Protection of encapsulated substances: provide
protection to encapsulated substances from degradation,
8. ________
…CHARACTERISTICS OF LIPOSOMES
Controlled release: can be designed to provide controlled
or sustained release, & so improve the effect and reduce the
frequent dosing.
Variability in size: can be engineered to have a specific
size range, which impacts their drug release properties and
biodistribution.
Enhanced Solubility: enhance the solubility of hydrophobic
drugs, making them more bioavailable and effective.
9. ________
APPLICATIONS OF LIPOSOMES IN OCULAR DDS
INTRAVITREAL APPLICATION
Formulated lipid prodrug of ganciclovir into liposomes as
antiviral treatment against herpes simplex virus. Intravitreal
injection with 0.2 nM intravitreal concentration was the most
effective without causing any side effects of vitreous clarity
or cataracts development in the eye. Moreover, this
formulation provided complete retinal protection even after
simultaneous intravitreal injection.
10. ________
…APPLICATIONS OF LIPOSOMES IN OCULAR DDS
TOPICAL APPLICATION
Topical administration of chitosan-coated liposomes
(chitosomes) improves precorneal retention and also slows
down drug metabolism at the precorneal epithelial surface.
Cationic liposomes containing herpes simplex virus (HSV)
antigens were proposed as potential carriers, in the form of
a periocular vaccine, to protect against subsequent HSV-1
ocular challenges.
11. ________
…APPLICATIONS OF LIPOSOMES IN OCULAR DDS
SUBCONJUNCTIVAL APPLICATION
Absorption rate of liposome-bound low molecular weight
heparin (LMWH) was investigated after subconjunctival
injection in the treatment of subconjunctival hemorrhage.
Low concentration of liposome-bound LMWH was observed
as compared to the free LMWH in the intraocular regions
(aqueous and vitreous). Moreover, lower systemic level of
LMWH was noted after subconjunctival injection
