Figure 2.

Trans-tympanic drug delivery. A) Schematic of trans-tympanic drug delivery systems. In non-invasive delivery, drug fluxes into middle ear fluid, with substantial dilution. It is unknown whether substantial drug flux can occur into the inner ear, or into the middle ear in the absence of fluid. Invasive delivery is via injection or incision into the middle ear, or in the round window niche, for drug flux into the middle or (more commonly) inner ear. Anatomy of B) noninvasive trans-tympanic drug delivery systems (TM: tympanic membrane, DDS: drug delivery system), C) invasive trans-tympanic drug delivery systems. RW: Round window. The ear anatomy and syringe images were adapted under the terms and conditions of the CC BY 3.0 Unported License. Copyright Servier Medical Art.