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Abstract
The low bioavailability and ocular residence time
exhibited by the topical conventional dosage forms
because of spoilage by overflow, dilution of drug by
tear turn over, nasolachrymal drainage and systemic
absorption may be overcome by use of ocular film systems
that are placed in cul de sac of the eye, where they
release the drug at predetermined rate for prolong
period of time. Brimonidine tartrate (BT) is a
α2-adrenergic receptor agonist acts via decreasing
synthesis of aqueous humor, and increasing the amount
that drains from the eye. Various formulations of films
of BT were formulated using different polymers. Ocular
films were characterized for thickness, surface pH,
weight per square cm, percentage moisture absorption,
percentage moisture loss, percent elongation, percentage
drug released and in vitro residence time were performed
by studying the diffusion through artificial membrane.
After sterilization IR spectral studies were done to
confirm the intactness of drug. In vitro study shows
that delivery system is capable of releasing the drug in
concentration independent mode, indeed the adaptability
of delivery to biological membrane. In conclusion, the
ocular films formulation achieved the target of the
above study such as reducing the frequency of
administration, avoiding the drug loss due to lachrymal
drainage and hence may increase patient compliance.
Introduction
The ophthalmic research now a day’s focuses on
developing systems which are not only prolong the
contact time of the vehicle with ocular surface, but
which would at the same time reduce elimination of the
drug. This approach is based on the supposition that the
drug is retained in the vehicle by bonds which are
sufficiently labile not to remain trapped beyond the
residence time of the vehicle in the precorneal region1.
Brimonidine tartrate (BT) is a α2-adrenergic receptor
agonist. It acts via decreasing synthesis of aqueous
humor, and increasing the amount that drains from the
eye2. As a treatment for glaucoma, it is usually given
in 0.2% w/v (2mg/ml) eye drop form is administered
two-three times daily3. The mean apparent half-life of
BT in the systemic circulation is approximately 3 hours
in humans after topical dosing. The plasma protein
binding of brimonidine after topical dosing in humans is
approximately 29%. The major part of the dose (around
75% of the dose) was excreted as metabolites in urine
within five days. It is used to treat open-angle
glaucoma or ocular hypertension and BT is also used to
induce miosis for people suffering from poor night
vision after Lasik or PRK surgery. The main objective of
the current research topic is to design as membrane
penetration controlled device using different polymers
in various proportions and combination.
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