Formulation and Evaluation of Brimonidine Tartrate Ocular Films

K.S.Rathore, R.K.Nema, S.S.Sisodia

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.
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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