Single Administration of a Sustained-Release Formulation of KB-R7785 Inhibits Tympanic Membrane Regeneration in an Animal Model

J Int Adv Otol. 2016 Dec;12(3):237-240. doi: 10.5152/iao.2016.3124.


Objective: A pressure equalization tube placed within the tympanic membrane is the only clinically available method for inhibiting tympanic membrane regeneration. Problems associated with this include associated otorrhea, biofilm formation, medial migration of the tube, tube retention, induction of granulation tissue, and a small but significant rate of cholesteatoma. We aimed to demonstrate that a single administration of a sustained-release polymer formulation of KB-R7785 maintains tympanic membrane perforation for at least 6 months.

Materials and methods: Sustained-release KB-R7785 was delivered within a novel polymer hydrogel to 20 mice with bilateral acute tympanic membrane perforations (a total of 40 perforations). The perforations were monitored at 3-month intervals until 9 months.

Results: At 3 months, 90% of perforations were open (n=36/40). At 6 months, 75% of perforations were open (total n=30/40). At 9 months, 22.5% of perforations were open (total n=6/40). The majority of tympanic membrane perforations (75%) were open (not healed) beyond 6 months and close (fully healed) prior to 9 months (77.5%). Once healed, tympanic membranes resembled their normal histological appearance.

Conclusion: This study demonstrates that a single administration of a sustained-release polymer formulation of KB-R7785 inhibits tympanic membrane regeneration for 6-9 months.

MeSH terms

  • Animals
  • Delayed-Action Preparations
  • Disease Models, Animal
  • Glycine / analogs & derivatives*
  • Glycine / pharmacology
  • Hydroxamic Acids / pharmacology*
  • Male
  • Mice
  • Mice, Inbred CBA
  • Regeneration / drug effects*
  • Tympanic Membrane Perforation / pathology*


  • Delayed-Action Preparations
  • Hydroxamic Acids
  • KB R7785
  • Glycine