title: Ototoxicity of gentian violet on the guinea pig cochlea.
abstract: OBJECTIVE
  Gentian violet (GV) is an antimicrobial and antifungal agent that has been used widely to treat intractable discharge in the ear. The purpose of this report is to warn clinicians about the ototoxic effect of GV in the middle ear.
  
  
  METHODS
  GV ototoxicity was evaluated by measuring compound action potentials (CAPs) in the VIIIth nerve in adult Hartley guinea pigs. The middle ear cavities of the animals were filled with GV solution (0.5% or 0.13%), and CAPs were measured after intervals of 5 and 30 minutes and 1, 2, 6, and 24 hours. After all measurements were completed, the temporal bones were harvested for histopathologic evaluation. Celloidin-embedded specimens were cut into 20-μm slices and examined using light microscopy. The bacteriostatic activity of GV was evaluated using a disk-diffusion assay.
  
  
  RESULTS
  A 0.5% GV solution produced a mild elevation in the CAP threshold at 30 minutes, a greater reduction at 1 hour, and complete abolishment of CAP at 24 hours. A 0.13% GV solution caused mild elevation in the CAP threshold at 2 hours and severe elevation at 6 hours. Massive new bone formation was found in the middle ear cavity at 6 weeks. GV concentrations of 0.13% and 0.06% were effective against all bacteria tested, with the exception of Pseudomonas aeruginosa.
  
  
  CONCLUSIONS
  Although GV has marked antibacterial and antifungal activities, its use should be limited to the external ear canal. GV exerts an ototoxic effect in a concentration- and time-dependent manner, and so the use of this drug in the middle ear cavity is not recommended.
authors.affiliation: *Department of Otolaryngology, School of Medicine, Fukuoka University; †Department of Pharmacy, and ‡Department of Clinical Laboratory, Fukuoka University Hospital; and §Department of Otolaryngology, Nishi Fukuoka Hospital, Fukuoka, Japan.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Higuchi
authors.forename: Takafumi
authors.initials: T
authors.lastname: Yamano
authors.forename: Hisamitsu
authors.initials: H
authors.lastname: Takase
authors.forename: Hisae
authors.initials: H
authors.lastname: Yoshimura
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakagawa
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Morizono
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology / Q000633:toxicity*; D001309:Auditory Threshold / Q000187:drug effects; D001419:Bacteria / Q000187:drug effects; D003051:Cochlea / Q000473:pathology*; D015834:Cochlear Diseases / Q000139:chemically induced* / Q000473:pathology; D015169:Colony Count, Microbial; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005840:Gentian Violet / Q000494:pharmacology / Q000633:toxicity*; D006168:Guinea Pigs; D008826:Microbial Sensitivity Tests; D013701:Temporal Bone / Q000473:pathology; D000160:Vestibulocochlear Nerve Diseases / Q000139:chemically induced / Q000473:pathology
chemical_list: D000890:Anti-Infective Agents; D005840:Gentian Violet