May 2008
Volume 49, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2008
The Correlation of an Innovative in vivo Dosing Method With Clinical Trial Results of the Ocular Penetration of Dexamethasone Using a New TobraDex Formulation
Author Affiliations & Notes
  • M. J. Brubaker
    Research & Development, Alcon Research Ltd, Fort Worth, Texas
  • L. Bernal-Perez
    Research & Development, Alcon Research Ltd, Fort Worth, Texas
  • A. C. Brooks
    Research & Development, Alcon Research Ltd, Fort Worth, Texas
  • G. R. Owen
    Research & Development, Alcon Research Ltd, Fort Worth, Texas
  • Footnotes
    Commercial Relationships  M.J. Brubaker, Alcon Research, Ltd., E; L. Bernal-Perez, Alcon Research, Ltd., E; A.C. Brooks, Alcon Research, Ltd., E; G.R. Owen, Alcon Research, Ltd., E.
  • Footnotes
    Support  None.
Investigative Ophthalmology & Visual Science May 2008, Vol.49, 5676. doi:https://doi.org/
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      M. J. Brubaker, L. Bernal-Perez, A. C. Brooks, G. R. Owen; The Correlation of an Innovative in vivo Dosing Method With Clinical Trial Results of the Ocular Penetration of Dexamethasone Using a New TobraDex Formulation. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5676. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : To determine and correlate the ocular penetration and distribution of dexamethasone using results from a clinical study with cataract patients and a rabbit model that simulates dosing in the human eye, comparing TobraDex® ophthalmic suspension to a new formulation containing half the concentration of dexamethasone in a novel suspension technology.

Methods: : In the clinical study, 957 patients received one drop of either TobraDex® ophthalmic suspension (tobramycin 0.3%, dexamethasone 0.1%) or TobraDex ST suspension (tobramycin 0.3%, dexamethasone 0.05%) at various time points prior to cataract surgery. Clinical samples of the aqueous humor were collected at the time of surgery. In the rabbit model, anesthetized rabbits were given a single topical dose of either suspension followed by a 60 minute controlled period that simulated the human eye with manual blinking (4 blinks/min) and supplementary tearing (2 µL/min). Tear samples were collected every 5 minutes, and after euthanasia, tissue samples were collected at 60 minutes. Dexamethasone concentrations were quantified using HPLC.

Results: : In the clinical study, after 60 minutes, the ratio of dexamethasone levels in the aqueous humor was 1.18 in favor of the new formulation (20.7 versus 17.5 ng/mL). In the rabbit model, the mean concentrations of dexamethasone [µg/mL or µg/g ± SE (n=4)] at 60 minutes were as follows: in the aqueous humor 0.77± 0.08 versus 0.64 ± 0.03 (ratio 1.20); in the conjunctiva 1.2 ± 0.3 versus 0.8 ± 0.2 (ratio 1.5); in the cornea 2.8 ± 0.5 versus 1.6 ± 0.4 (ratio 1.75); in the sclera 0.77 ± 0.08 versus 0.64 ± 0.03 (ratio 1.2); and in the iris-ciliary body 2.1 ± 0.3 versus 1.6 ± 0.3 (ratio 1.3). In the rabbit tears, 10 minutes after dosing, the dexamethasone levels were 37 ± 11 versus 11 ± 6 (ratio 3.4).

Clinical Trial: : www.clinicaltrials.gov NCT00473070

Keywords: cataract • corticosteroids • aqueous 
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