ear, nose, and throat disorders
Drug Induced Ototoxicity
Introduction
A wide variety of drugs can be ototoxic. Medication-related factors affecting ototoxicity include Dose Duration of therapy Concurrent renal failure Infusion rate Lifetime dose Coadministration with other medications that have ototoxic potential Genetic susceptibility Ototoxic medications should not be used for otic topical application when the tympanic membrane is perforated because the medications might diffuse into the inner ear. Aminoglycosides, including the following, can affect hearing: Streptomycintends to cause more damage to the vestibular portion than to the auditory portion of the inner ear. Although vertigo and difficulty maintaining balance tend to be temporary, severe loss of vestibular sensitivity may persist, sometimes permanently. Loss of vestibular sensitivity causes difficulty walking, especially in the dark, and oscillopsia (a sensation that the environment is bouncing with each step). About 4 to 15% of patients who receive 1 g/day for>1 week develop measurable hearing loss, which usually occurs after a short latent period (7 to 10 days) and slowly worsens if treatment is continued. Complete, permanent deafness may follow. Neomycinhas the greatest cochleotoxic effect of all antibiotics. When large doses are given orally or by colonic irrigation for intestinal sterilization, enough may be absorbed to affect hearing, particularly if diffuse mucosal lesions of the colon are present.Neomycinshould not be used for wound irrigation or for intrapleural or intraperitoneal irrigation because massive amounts of the medication may be retained and absorbed, causing deafness. Kanamycin andamikacinare close toneomycinin cochleotoxic potential and are both capable of causing profound, permanent hearing loss while sparing balance. Gentamicinandtobramycinhave vestibular and cochlear toxicity, causing impairment in balance and hearing. Vancomycincan cause hearing loss, especially in patients with renal insufficiency. Some mitochondrial DNA mutations predispose to aminoglycoside ototoxicity. Azithromycin, a macrolide, causes reversible or irreversible hearing loss in rare cases. Viomycin, a basic peptide with antituberculous properties, has cochlear and vestibular toxicity. Chemotherapeutic(antineoplastic) medications,particularly those containing platinum (cisplatinandcarboplatin), can cause tinnitus and hearing loss. Hearing loss can be profound and permanent, occurring immediately after the first dose, or it can be delayed until several months after completion of treatment. Sensorineural hearing loss occurs bilaterally, progresses decrementally, and is permanent. Ethacrynic acidandfurosemidegiven IV have caused profound, permanent hearing loss in patients with renal failure who had been receiving aminoglycoside antibiotics. Salicylatesin high doses (>12 325-mg tablets ofaspirina day) cause temporary hearing loss and tinnitus. Quinineand its synthetic substitutes can cause temporary hearing loss. (See also Hearing Loss .) 