Solutions, topical eyedrops

Oils have been used as vehicles for several topical eyedrop products that are extremely sensitive to moisture. Tetracycline HC1 is an antibiotic that is stable for only a few days in aqueous solution. It is supplied as a 1% sterile suspension with Plastibase 50W and light liquid petrolatum. White petrolatum and its combination with liquid petrolatum to obtain a proper consistency is routinely used as the vehicle for ophthalmic ointments. 

Dorzolamide Hydrochloride is an inhibitor of human carbonic anhydrase II. The inhibition of carbonic anhydrase in the ciliary processes of the eye decreases the secretion of aqueous humor, with a resulting reduction in intraocular pressure. The drug is formulated as an ophthalmic solution, and administered topically as eyedrops. 

Both our group [172] and Pate et al. [173] found that anandamide in nor-motensive rabbits, on topical application, reduces IOP. In the report by Pate et al. anandamide was dissolved in an aqueous solution of a cyclodextrin, single eyedrops were instilled in one of the eyes and the changes in IOP were compared to those of the untreated eye. Topical application of 31.25 fig caused an immediate reduction of IOP. A dose of 62.5 fig induced an initial increase and a subsequent decrease of IOP below baseline, while a dose of 125 fig caused a significant increase without the subsequent decrease of IOP. 

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