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An Anterior Chamber Toxicity Study Evaluating
Besivance, AzaSite, ciprofloxacin and BSS
Authors Peter J. Ness, Nick Mamalis, Liliana
Werner, Surekha Maddula, Don K. Davis, Eric D.
Donnenfeld, Randall J. Olson
From the John A. Moran Eye Center, University of
Utah

• The authors have no financial or proprietary
  interest in any product mentioned in this poster
  Randall J. Olson is a consultant for Allergan,
  Inc.

- This study is supported by unrestricted grants
from Allergan, Inc. and Research to Prevent
Blindness, Inc.
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Background

• Postoperative endophthalmitis is an uncommon but
  devastating complication of cataract surgery.
• Postoperative endophthalmitis prophylaxis1
• Widely used around the world
• All antibiotics are used off-label in this
  setting in the US
• Has been shown to decrease risk of
  endophthalmitis
• Sutureless clear corneal cataract surgery2,3
• Decreases astigmatism
• Not all wounds are as well sealed as we wish
• Leaky wounds allow the tear film to enter the
  anterior chamber
• The tear film entering the eye contains
  antibiotics and other medications being
  administered

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Background

• Besivance (besifloxacin) and AzaSite
  (azithromycin)
• The first drugs using the DuraSite
  bio-adhesive vehicle
• Approved in the US to treat bacterial
  conjunctivitis
• DuraSite benefits
• Prolonged administration of the medication on the
  ocular surface as the antibiotic-embedded polymer
  is slowly broken down
• Less frequent dosing is required for equivalent
  efficacy4
• Better patient compliance
• Why not use these helpful antibiotics for
  postoperative endophthalmitis prophylaxis?

Bausch Lomb, Rochester, NY, USA Inspire
Pharmaceuticals, Inc., Durham, NC, USA
InSite Vision Inc., Alameda, CA, USA
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Objective

• No studies, to date, have investigated the
  effects of DuraSite-based medications in the
  anterior chamber.
• Our aim in this study was to evaluate the
  possible toxicity of DuraSite-based medications,
  delivered as a large bolus, into the anterior
  chamber of rabbit eyes, simulating an extremely
  leaky clear corneal wound.

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Methods/Materials

• Subjects 20 New Zealand White Rabbits
• Study groups Besivance 0.6, AzaSite 1.0,
  ciprofloxacin 0.3 and balanced salt solution
  (BSS) (10 eyes randomized into each group)
• Surgical technique sterile aspiration of 0.1 mL
  of aqueous from the anterior chamber using a 30 g
  needle, then injection of 0.1 mL of the study
  material through the same needle
• Postoperative examinations slit-lamp exams (by a
  masked physician) at 24 and 48 hours after
  injection, focusing on inflammatory signs
• Sacrifice each rabbit was humanely euthanized at
  48 hours post-injection and all eyes enucleated
• Data analysis
• Corneal vital staining 2 eyes randomized from
  each group
• Histopathology remaining 8 eyes from each group
• Analysis focused on damage to the corneal
  endothelial cell layer and other signs of
  anterior segment damage
• Outcome measures clinical and pathologic signs
  of toxicity

Falcon Pharmaceuticals, Fort Worth, TX, USA
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Results

• Clinical Slit-Lamp Exam (DuraSite-based groups)
• Severe, diffuse corneal edema (20 of 20 eyes)
• Corneal ectasia and bullous keratopathy (20 of 20
  eyes)
• Profound conjunctival injection
• Moderate limbal vascularity
• Generally increased globe size
• No statistically significant difference between
  Besivance and AzaSite examination scores

Figure 2. Ruptured bullae and corneal edema after
injection of Besivance
Figure 1. Diffuse corneal edema after injection
of Besivance
Figure 3. Corneal ectasia and bullous keratopathy
after injection of AzaSite
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Results

• Clinical Slit-Lamp Exam (Non-DuraSite-based
  groups)
• No corneal opacity (19 of 20 eyes)
• Mild conjunctival injection (12 of 20 eyes)
• Mild limbal vascularity (16 of 20 eyes)
• Mild conjunctival injection discharge with
  moderate diffuse corneal opacification and limbal
  vascularity (1 eye injected with ciprofloxacin
  Figure 6)
• No statistically significant difference between
  ciprofloxacin and BSS examination scores

Figure 5. Clear cornea with no signs of
inflammation after injection of ciprofloxacin
Figure 4. Clear cornea and mild conjunctival
injection after injection of ciprofloxacin
Figure 6. Diffuse moderate corneal edema after
injection of ciprofloxacin
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Results
Table. Globe volume by gross measurements after
enucleation
Besivance AzaSite Ciprofloxacin BSS
Globe volume (standard deviation) cm3 3.05 (0.17) 3.16 (0.52) 2.46 (0.13) 2.56 (0.17)

• Corneal vital staining
• DuraSite-based eyes revealed
• Severe alteration of endothelial cell size and
  shape indicative of damage
• Non-DuraSite-based eyes showed
• Mild intracellular edema
• Iintact hexagonal shape of endothelial cells

Figure 7. Corneal vital staining with
morphologically damaged endothelial cells after
injection of AzaSite
Figure 8. Corneal vital staining with mild
intracellular edema after injection of BSS
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Results

• Histopathology
• DuraSite-based eyes showed (to varying degrees in
  each eye)
• Bullous keratopathy
• Corneal stromal thinning
• Anterior chamber fibrin
• Extensive endothelial cell attenuation
• Peripheral anterior synechia (in some eyes)
• Amorphous eosinophilic material within the
  iridocorneal angle and trabecular meshwork
• Non-DuraSite-based eyes showed
• No signs of inflammation or anterior segment
  damage

Figure 9. Histopathologic slide showing fibrin,
amorphous material in iridocorneal angle and
acute inflammatory cells after injection of
Besivance, HE, 100x
Figure 10. Histopathologic slide showing a large
epithelial bulla, corneal edema and fibrin in the
anterior chamber after injection of Besivance,
HE, 40x
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Discussion

• Although the literature has clearly shown
  benefits of Besivance and AzaSite, their safety
  in the setting of sutureless clear corneal wounds
  (i.e. post cataract surgery) has not been
  investigated.
• DuraSite medications seem to cause glaucomatous
  and toxic damage in the anterior chamber when
  injected intracamerally as a large bolus.
• The difference in effect between DuraSite-based
  and non-DuraSite-based medications was
  statistically significant.

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Discussion/Conclusions

• Each medication is composed of various
  components antibiotic, benzalkonium chloride
  (BAK) preservative, vehicle and other inactive
  ingredients.
• BAK is contained in all 3 medications at
  differing concentrations (Besivance 0.01,
  AzaSite 0.003, ciprofloxacin 0.006)
• These concentrations are within the range
  previously reported to possibly cause endothelial
  toxicity in rabbits5 therefore, it is logical to
  conclude that BAK caused the toxic reaction
• If BAK had caused this toxicity, we would expect
  some dose-response relationship, BUT instead
  there was a poor correlation between BAK
  concentration and toxicity (e.g. Besivance and
  AzaSite appeared equally toxic) therefore, it is
  unlikely to have caused the noted toxicity
• The vehicle (DuraSite) alone was not used as a
  control due to commercial unavailability, so the
  authors used a variety of DuraSite and
  non-DuraSite medications (all commonly used in
  ophthalmic practice) for comparison
• We deduce that the DuraSite component of
  Besivance and AzaSite caused the toxicity and
  glaucomatous damage
• We recommend
• Further study of these medications at lower
  volumes in the anterior chamber
• Until the safety is better established, surgeons
  should consider placing a suture over a clear
  corneal wound if DuraSite-based medications may
  be used

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References

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