By Colleen G. Le Prell
This article is a part of the November/December, Volume 34, Number 6, Audiology Today issue.
Although many audiologists did not receive pharmacology education during their clinical education, they are responsible for collecting information about prescription medications, identifying the extent to which those medications may influence patient hearing and balance, and communicating with prescribing physicians.
In addition, scientists and industry are actively investigating experimental drugs that could one day be approved by the U.S. Food and Drug Administration (FDA) for hearing loss prevention or the recovery of auditory function. Thus, in addition to having basic knowledge about prescription drugs that can affect hearing and balance, audiologists should be prepared to answer or refer patients’ questions about investigational inner ear medicines. This article introduces information relevant to audiologists’ knowledge and clinical practice in the above areas.
Pharmacokinetic Parameters
Pharmacology is the science that concerns itself with the fate and actions of drugs in the body (Meldrum, 2007). Pharmacokinetics and pharmacodynamics, respectively, document how drugs get to target locations (including absorption, distribution, metabolism, and excretion [ADME] measurements) and actions of the drug at its target location (including patient factors such as drug tolerance and drug interactions) (Meldrum, 2007; Spruill et al, 2014).
Pharmacokinetic and pharmacodynamic measures are uniquely difficult to collect for inner ear medications due to the inaccessibility of the inner ear (Cousins, 2019). Because the inner ear cannot be readily accessed, indirect measurements using blood, plasma, urine, saliva, or other proxy measures must be relied on. Indirect measures may not accurately predict drug concentrations in the inner ear, however, as the blood-brain barrier and blood-labyrinth barriers restrict drugs that are systemically administered from accessing the inner ear (Bielefeld and Kobel, 2019).
Local delivery of inner ear medicines via the middle ear space has the potential to increase drug availability in the cochlea and reduce unwanted side effects—a consideration that is particularly important for regeneration therapies (Liu and Yang, 2022). The study of toxic effects of drugs is termed toxicology (Meldrum, 2007). Detailed discussion of all of the above terms and examples relevant to audiologists are available in the article by Offerdahl and Mishra (2019).
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