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P. O. Pellinen, J. Lokkila; Corneal Penetration Into Rabbit Aqueous Humor Is Comparable Between Preserved and Preservative-Free Tafluprost. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3825.
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Benzalkonium chloride (BAK) is a preservative used in antiglaucoma medications. Evidence from some rabbit and human studies suggests that high concentrations of BAK may affect the corneal epithelium layer and thus increase the transcorneal penetration of poorly permeable drugs. However, there are also contradictory studies showing that BAK does not affect penetration. Tafluprost is a new prostaglandin analogue in development. The aim of this study was to compare the corneal penetration into rabbit aqueous humor of preserved and preservative-free tafluprost following topical administration.
48 male New Zealand albino rabbits were divided into 6 groups. In each group 8 rabbits received a single topical dose of 30 µl preservative-free tafluprost 0.0015% eye drops and tafluprost 0.0015% eye drops preserved with 0.01% benzalkonium chloride (BAK) into the right or left eye. Rabbits were euthanized at defined time point (either 45 min, 1.5, 2, 3, 6 and 8 hours after the dose). Concentrations of tafluprost acid (AFP-172) in rabbit aqueous humor were measured by using high performance liquid chromatography coupled with single quad mass spectrometry with electrospray ionization and pharmacokinetic parameters calculated from obtained results.
The maximum concentration (Cmax) values after 45 minutes were 4.50 ng/ml for preservative-free tafluprost and 3.99 ng/ml for preserved tafluprost. The area under the concentration-time curves from 45 minutes to 3 hours was 5.14 ng h/ml for preservative-free tafluprost and 4.54 ng h/ml for preserved formulation.
These data show that, after a single ocular instillation, the corneal penetration into rabbit aqueous humor is comparable between preserved and preservative-free tafluprost. Therefore, BAK does not affect corneal penetration of tafluprost into the rabbit aqueous humor.
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