Application of Nanotechnology for Ocular Drug Delivery
Brinzolamide, polyneuic nanopanticles, Ocular
Brinzolamide, a carbonic anhaydrase inhibitor, is commercially formulated as a 1% ophthalmic suspension to reduce intraocular pressure (IOP). The commercially available preparation of brinzolamide is Azopt® (Alcon Laboratories, Inc, Ft. Worth, Texas, USA). The most common ocular adverse events on using brinzolamide eye drops are blurred vision (3–8%), ocular discomfort (1.8–5.9%) and eye pain (0.7–4.0%). Other ocular adverse events occurring at an incidence of less than 3% include hyperemia, pruritus, tearing, discharge, blepharitis, keratitis, foreign body sensation, dry eye, conjunctivitis and lid margin crusting.Antiglaucoma agents may be administered topically or systemically for the treatment of elevated IOP. Topical application of drugs has remained the most preferred method due to ease of administration and low cost. Anatomical and physiological barriers hinder drugs from reaching posterior segment of the eye, mainly at choroid and retina. A major fraction of drug following topical administration is lost by lacrimation, tear dilution, nasolacrimal drainage and tear turnover. Such precorneal losses result in very low ocular bioavailability. Typically, less than 5% of the total administrated dose reaches aqueous humor. Therefore, in order to maintain minimum effective concentrations, the agents need to be frequently dosed resulting in poor patient compliance. Topical medications have been also noted to induce long term ocular surface changes which may oftencause damage to conjunctival and corneal cells. The deleterious effects of preservatives on the ocular surface are of particular concern for patients with chronic conditions such as glaucoma or keratoconjunctivitis sicca. Repeated application of multiple medications can lead to significant accumulation of preservative in ocular tissue and increased risk of ocular surface damage.