Inner ear lidocaine concentrations following iontophoresis.
This study has established the feasibility of measuring perilymph lidocaine levels after iontophoresis for local tympanic anesthesia in the rabbit model. A subsequent study may now be performed to produce a valid, dose-response curve correlating perilymph lidocaine levels and cochlear responses. In this manner the effects of and safety of lidocaine iontophoresis for tympanic anesthesia can be determined with certainty. After intravenous sedation, eight rabbits underwent iontophoresis followed by diagnostic vestibulotomies. Perilymph samples were taken and analyzed for lidocaine levels. Significant amounts of perilymph lidocaine were found in both the intact and perforated tympanic membrane groups. In the perforated tympanic membrane group, the perilymph lidocaine level was eight times that of the intact tympanic membrane group. Future studies to determine the dose-response relationship of perilymph lidocaine to cochlear responses are now possible. Thus, the safety of lidocaine iontophoresis and the degree of inner ear toxicity of lidocaine can be established quantitatively.
D000818:Animals; D003051:Cochlea / Q000187:drug effects; D007758:Ear, Inner / Q000032:analysis*; D007478:Iontophoresis / Q000295:instrumentation; D008012:Lidocaine / Q000032:analysis* / Q000633:toxicity; D008954:Models, Biological; D011817:Rabbits
D008012:Lidocaine