Safety and pharmokinetics of triamcinolone hexacetonide in rabbit eyes

Muhammad M. Abd-El-Barr, Thomas A. Albini, Petros E. Carvounis, Feng He, Roberta P.A. Manzano, Patricia Chévez-Barrios, Theodore G. Wensel, Samuel M. Wu, Eric Holz

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Purpose: The aim of this study was to evaluate whether intravitreal triamcinolone hexacetonide (TH) is a safe, longer lasting alternative to intravitreal triamcinolone acetonide (TA) in the rabbit eye. Methods: Three groups, each comprising of 15 Dutch-belted rabbits, received a unilateral injection of 0.1 mL of drug and 0.1 mL of physiologic salt solution in the fellow eye. Group I received TA, group II received commercially available TH, and group III received reformulated iso-osmolar triamcinolone hexacetonide (rTH). Simultaneous bilateral dark-adapted electroretinography was performed following the injection. Retinal morphology was assessed by using histopathology in each group enucleated 12 weeks after injection. High-performance liquid chromatography of vitreous isolated from the enucleated eyes was used to determine drug concentrations. Results: A significant reduction in saturated a-wave and maximal scotopic b-wave was observed in the group II eyes relative to the fellow control eyes at both 2 and 12 weeks postinjection (P < 0.001 for each comparison) but not in the other groups. Histopathology showed no differences between drug-injected eyes and fellow control eyes in groups I and III, but in group II there was severe degeneration of all retina layers. In group I, the drug half-life was 17.7 ± 1.7 days, group II 44 ± 13 days, and group III 12.8 ± 2.3 days. Conclusions: The half-life of commercially available TH in the vitreous is double that of TA, but the former is toxic to the retina in this rabbit model. Reformulated iso-osmolar TH showed no evidence of deleterious effects to retina function or structure but had a similar half-life to TA.

Original languageEnglish (US)
Pages (from-to)197-205
Number of pages9
JournalJournal of Ocular Pharmacology and Therapeutics
Issue number2
StatePublished - Apr 1 2008

ASJC Scopus subject areas

  • Ophthalmology
  • Pharmacology
  • Pharmacology (medical)


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