Figure 6.

Perilymph concentrations resulting from RW niche applications for 3 drugs. Black lines show the group mean measured perilymph concentrations in 10 sequential samples taken from the lateral semi-circular canal. The number of experiments were 4, 4 and 5 respectively. Concentrations are normalized (as %) of the drug concentration applied to the RW niche. The applied concentration of dexamethasone was 94.2 μg/ml (dissolved concentration in an applied 4.5% suspension), of dexamethasone-phosphate was 4 mg/ml and of gentamicin was 40 mg/ml respectively. The approximate spatial origins of the perilymph samples are given in the first panel. Colored curves are simulations of the experiments calculated for each of the 3 time courses of drug decline in the middle ear. A, blue: unchanging with time, comparable to micronized dexamethasone suspension, B, red: 74.5 min middle ear decline half-time, comparable to gentamicin solution, C: green: 25.7 min middle ear decline half-time, comparable to dexamethasone phosphate. These decline rates correspond to the curves shown in Figure 4, and are detailed in the text. Dexamethasone and dexamethasone-phosphate data are from Salt et al., 2018 and gentamicin data are from Salt et al., 2016.