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. Author manuscript; available in PMC: 2019 Oct 1.
Published in final edited form as: Hear Res. 2018 Mar 11;368:28–40. doi: 10.1016/j.heares.2018.03.002

Figure 8.

Figure 8

Influence of drug properties and application protocols on calculated drug levels achieved in different regions of the human inner ear using kinetic parameters established in the studies above. Sustained delivery from a suspension of dexamethasone results in the generation of a steady-state, with substantial concentration gradients between the vestibule and the cochlea, and between high-frequency and low-frequency cochlear regions. In contrast, delivery of dexamethasone-phosphate solution results in a transient drug exposure, primarily to vestibular and high-frequency cochlear regions, due to the rapid rate of elimination of dexamethasone from perilymph. Delivery of gentamicin also results in a transient drug exposure, with greater spread to low frequency cochlear regions then dexamethasone-phosphate, due to a lower rate of elimination from cochlear perilymph.