Ophthalmic vehicles containing polymer-solubilized tropicamide: "in vitro/in vivo" evaluation
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Updated: Sep 10, 2026

Use of Rabbit Eyes in Pharmacokinetic Studies of Intraocular Drugs
Published on: July 23, 2016
C Carmignani1, S Rossi, M F Saettone
1Department of Bioorganic Chemistry and Biopharmaceutics, University of Pisa, Italy.
Abstract:
Commercial 1.0% aqueous tropicamide (TR) eyedrops are buffered to pH 4.4-5.0 to produce sufficiently stable solutions of the weakly basic, poorly soluble drug. These acidic solutions, however, are irritants and may induce copious lachrimation, thus reducing the drug bioavailability. The aim of the present study was to evaluate some solubilizing agents for the preparation of 1.0% TR ophthalmic solutions adjusted at physiologically compatible pH, potentially showing increased eye tolerance, activity, and stability when compared with standard commercial eyedrops. The tested solubilizers were two non-ionic surfactants-Tyloxapol (TY) and Cremophor EL (CR) and one polymer, Pluronic P85 (PL). Four stable 1% TR formulations, containing 3% TY, 7.5% CR, 15% PL, or 5% CR + 10% PL were submitted to mydriatic activity tests in rabbits. They improved to a small but statistically significant extent the AUC for mydriatic effect of TR in the test animals when compared with commercial 1.0% TR eyedrops.
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