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An Earful of Science about Auditory Safety
Safety Assessment
Rachel Tapp

An Earful of Science about Auditory Safety

From dosing to choice of animal, five key considerations to think about when designing ototoxicity studies for drugs   

For drugs administered into the middle ear, those expected to come in contact with the middle or inner ear tissues, or drugs in a class of risk for ototoxicity, auditory safety evaluations are recommended. These assessments require a highly specialized set of tests to obtain the necessary data in order to identify the ototoxicity of a compound. Before you begin your auditory safety program, there are several questions you should consider that can impact the feasibility and design of your study. 

  1. Have you considered your dose volume limitations for specialized compartments? You will need to consider your formulations carefully. These specialized compartments are limited in size so standard toxicology dose volumes are not appropriate. Formulation of materials will be in microliter volumes, so solubility and maximum feasible concentrations should take these limitations into consideration.
  2. Which species are you planning for your ototoxicity safety studies? Do you need to include a non-rodent? The primary animal model for auditory drug safety characterization is the guinea pig. Drug sensitivity and anatomical similarity to humans make the guinea pig most suitable for this type of specialized testing. The use of alternative small animal (i.e. rat) species may be justified in some cases. It is necessary to consider the need to test for potential ototoxicity in a non-rodent species.
  3. Have you had discussions with the regulatory body agency with which you are filing? Regulatory bodies can provide you with the requirements and necessary guidance for your compound, as well as give you feedback on your approach.
  4. What is your dosing regimen, and how are you planning to get materials into the ear? For ototoxicity studies that require direct middle ear exposure, you can typically use transtympanic administration or implanted middle ear catheters.
  5. What are your timelines? Many factors will impact your development timeline; it is highly recommended that you discuss your expectations at length with an experienced Study Director during the planning stages of your program.

An earlier version of this blog post was published by MPI Research, now part of Charles River. If you are interested in ototoxicity check out this post.