Albumin Levels in Tear Film Modulate the Bioavailability of Medically-Relevant Topical Drugs.

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Sebbag L, Moody LM, Mochel JP

Albumin Levels in Tear Film Modulate the Bioavailability of Medically-Relevant Topical Drugs.

Front Pharmacol. 2020 Jan 28;10:1560. doi: 10.3389/fphar.2019.01560. eCollection 2019.

PubMed ID
32047429 [ View in PubMed
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Abstract

The breakdown of blood-tear barrier that occurs with ocular pathology allows for large amounts of albumin to leak into the tear fluid. This process likely represents an important restriction to drug absorption in ophthalmology, as only the unbound drug is transported across the ocular tissue barriers to exert its pharmacologic effect. We aimed to investigate the effects of albumin levels in tears on the bioavailability of two commonly used ophthalmic drugs: tropicamide, an antimuscarinic that produces mydriasis and cycloplegia, and latanoprost, a PGF2alpha analog used for the treatment of glaucoma. Eight female beagle dogs underwent a randomized, vehicle-controlled crossover trial. For each dog, one eye received 30 microl of artificial tears (control) or canine albumin (0.4 or 1.5%) at random, immediately followed by 30 microl of 1% tropicamide (2 days, 24 h washout) or 0.005% latanoprost (2 days, 72 h washout) in both eyes. Pupil diameter (digital caliper) and intraocular pressure (IOP; rebound tonometry) were recorded at various times following drug administration (0 to 480 min) and compared between both groups with a mixed model for repeated measures. Albumin in tears had a significant impact on pupillary diameter for both tropicamide (P /= 0.663). The IOP, only measured in eyes receiving latanoprost, was not significantly impacted by the addition of either 0.4% (P = 0.242) or 1.5% albumin (P = 0.879). Albumin in tear film, previously shown to leak from the conjunctival vasculature in diseased eyes, may bind to topically administered drugs and reduces their intraocular penetration and bioavailability. Further investigations in clinical patients and other commonly used ophthalmic medications are warranted.

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