April 2014
Volume 55, Issue 13
ARVO Annual Meeting Abstract  |   April 2014
In vivo rabbit tolerability and safety of a Manuka honey-based eye preparation for blepharitis
Author Affiliations & Notes
  • Jennifer P Craig
    Ophthalmology, University of Auckland, Auckland, New Zealand
  • Ilva D Rupenthal
    Ophthalmology, University of Auckland, Auckland, New Zealand
  • Ali Seyfoddin
    Ophthalmology, University of Auckland, Auckland, New Zealand
    School of Pharmacy, University of Auckland, Auckland, New Zealand
  • Amy Chen
    Ophthalmology, University of Auckland, Auckland, New Zealand
    Optometry and Vision Science, University of Auckland, Auckland, New Zealand
  • Grant Watters
    Ophthalmology, University of Auckland, Auckland, New Zealand
  • Footnotes
    Commercial Relationships Jennifer Craig, Manuka Health NZ Ltd (F); Ilva Rupenthal, Manuka Health NZ Ltd (F); Ali Seyfoddin, Manuka Health NZ Ltd (F); Amy Chen, Manuka Health NZ Ltd (F); Grant Watters, Manuka Health NZ Ltd (F)
  • Footnotes
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Investigative Ophthalmology & Visual Science April 2014, Vol.55, 3668. doi:
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    • Get Citation

      Jennifer P Craig, Ilva D Rupenthal, Ali Seyfoddin, Amy Chen, Grant Watters, Ocular Surface Laboratory; In vivo rabbit tolerability and safety of a Manuka honey-based eye preparation for blepharitis. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3668.

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

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Purpose: Methylglyoxal (MGO) derived from New Zealand’s native Manuka honey (MH), demonstrates antibacterial properties that may be beneficial in the treatment of blepharitis. MH complexed with α-cyclodextrin increases bioavailability of the active ingredient (Manuka Honey CycloPower™ (MHCP), Manuka Health, NZ). With safety previously confirmed in vitro, this project sought to undertake in vivo safety testing of a novel formulation designed for topical eyelid application, containing MHCP in a microemulsion (ME) base.

Methods: Six male NZ white rabbits were administered 20µl of 10% MHCP (100MGO) in ME to the right eye, (diluted 1:10 in PBS as estimate of potential tear film contamination), and 20µl of saline (0.9% NaCl) to the left eye, instilled directly into the conjunctival sac daily, on 5 consecutive days. Tear film and ocular surface characteristics were compared before and after instillation, daily. Lipid layer grade, tear evaporation rate, osmolarity and production were assessed as well as ocular surface fluorescein staining, conjunctival hyperemia and corneal clarity. Subsequently, following washout, 20µl of undiluted formulation was instilled into one eye of each rabbit to confirm safety, and the ocular surface evaluated on the same day, after 0.5, 5 and 10 min.

Results: No statistically or clinically significant changes in lipid grade, tear production, evaporation rate, fluorescein staining or hyperemia were observed in either eye, across the 5 days (Repeated measures ANOVA/Friedman, p>0.05). Mean osmolarity decreased following instillation of formulation and control drops, but excepting Day 1 for MHCP (p=0.027), differences were not statistically significant (p>0.05). Bulbar hyperemia and lowered tear osmolarity induced by the undiluted formulation returned to baseline levels within 10 min.

Conclusions: Instilled at a concentration as high as 10% on 5 consecutive days, the MHCP formulation showed no significant adverse immediate or cumulative effects. Exposure to the tear film and ocular surface is unlikely to reach such high levels clinically when the preparation is applied topically to the eyelids. Instillation of the undiluted preparation, simulating accidental in-eye application, was transient and not associated with significant discomfort. The novel MHCP formulation appears safe and thus continues to show potential for development as a preparation for managing blepharitis.

Keywords: 486 cornea: tears/tear film/dry eye • 467 clinical laboratory testing • 620 ocular irritancy/toxicity testing  

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