Hydrogel in drug delivery systems

‘

~ Polymeric materials that do not dissolve in water at physiological
conditions .

~ Shows extraordinary capacity for imbibing water into their
network structure.

~ Exhibits a phase transition in response to change in
external conditions such as pH ionic strength,
temperature and electric currents known as ‘smart’
gels.

~ 3D hydrophilic networks retain a large amount of water
that maintains a certain degree of structural integrity and
elasticity due to the presence of hydrophilic functional
groups in their structure



• Hydrogels provide a prolonged ocular residence time of
drugs.

• Hydrogels can also represent the oculr drug delivery system
resistant device due to their elastic properties.

• In situ gel system is generally preferred because of their
facility in dosing as a liquid and their long term retention
property as a gel after dosing.

• Thermosensitive, specific ion sensitive or pH sensitivee
hydrogels examined for their potential as vehicles for ocular
drugs.

• Poloxamers as thermogelling polymers are applicable for the
development of effective ophthalmic drug delivery.

Combination of Pluronic analogs or An alternate in situ gelling
addition of polymers eg material of natural origin,
(xycloglucan), is evaluated for the
PEG[45], PAA [46], methycellulose sustained ocular delivery of
(MC), HPMC, CMC[47] is necessary to Pilocarpine and Timolol.
achieve a phase transition and gelling

at precorneal temperature.

Combination of PAA with a suitable FACT
viscosity enhancing eg HPMC or MC Pilocarpine drops
can cause miosis
allows a reduction of PAA by draining the
concentration without comprising in
fluid from the
situ gelling properties eyeballs

Gellan containing formulations of Gels that are transformed via
pilocarpine hydrochloride allows aqueous solutions of PAA due to
the increase in pH can be used as in
reduction of the drug
concentration situ gelling ophthalmic drug
delivery system

Contact ~ Can be classified as hard or soft contact lenses according to their

• lens

elasticity. Only soft contact lenses are based on hydrogels.

Soft contact lens Silicone Hydrogel Lens
~ Approved for continuous wear for up
• Produced with different to 30 days
~Available in two base curves in a wide
techniques such as spin- array of powers including plano
~ It has stiffer modulus
casting, mold-casting and
Therapeutic hydrogel lens
lathe-casting. ~ Very useful in pain management of a
• Sufficient oxygen
wide array of conditions
permeability ~ May cause recurrent corneal
• Lens surfaces should have erosions in prolonged use of lens.
~ Used in Pain management for
excellent wettability in order conditions like Filamentary keratitis,

to avoid tear-film deposits. bullous keratopathy and etc
• Can also potentially be used

for drug delivery to the eye.
• Should have good tensile

properties
• Types of soft hydrogel lens

~ Silicone hydrogel lens

~ Therapeutic hydrogel lens

MAKING OF
CONTACT
LENS VIA
LATHE-
CASTING