Repeated measurements of compound action potential: evaluation of the ototoxicity of otic drops.
Consecutive CAP threshold shifts were studied in chinchillas following round window application of Cortisporin Otic Suspension for 10 minutes. A marked deterioration in CAP threshold was observed at 24 hours following otic application but these threshold shifts were reversible at lower frequencies. The shifts were progressive at higher frequencies at the 4 week measurement. The progressive high frequency loss with recruitment and with normal EP levels implies some hair cell dysfunction due directly to Cortisporin Otic Suspension ototoxicity and/or secondarily to middle ear inflammatory reactions to the otic. Short-term studies of ototopical drugs may result in misleading assessments as to the pattern and degree of ototoxicity. Long-term (i.e., one month or longer) studies are recommended for accurate ototoxicity assessment.
Morizono
T
T
Department of Otolaryngology, University of Minnesota Medical School, Minneapolis.
Tono
T
T
Sano
N
N
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001309:Auditory Threshold; D002682:Chinchilla; D003051:Cochlea / Q000187:drug effects*; D004432:Ear, Middle / Q000187:drug effects; D005260:Female; D006309:Hearing / Q000502:physiology; D006311:Hearing Disorders / Q000139:chemically induced*; D008297:Male; D010033:Otitis Media / Q000188:drug therapy; D011112:Polymyxin B / Q000008:administration & dosage / Q000494:pharmacology* / Q000633:toxicity
D011112:Polymyxin B