Ototoxic Effects from Gentamicin Ear Drops

PRACTICE H EALTH AND D RUG A LERTS

Ototoxic effects from gentamicin ear drops

Reason for posting: Gentamicin ear age was often persistent: in 16 patients fects after the first 5–7 days of use, and drops can cause serious side effects the symptoms had not resolved at the regularly thereafter if treatment is pro- (e.g., vertigo, imbalance, ataxia, oscillat- time the case was reported to Health longed. Audiometric assessment is not ing vision, hearing loss and tinnitus) Canada.5 an appropriate screening tool for oto- when used by patients with perforated toxicity,11 because ototoxic effects of tympanic membranes or tympanostomy The drug: Several preparations of topical topical gentamicin solutions appear to tubes.1 Despite previous warnings2–4 gentamicin sulfate solution are marketed be primarily vestibular rather than ototoxic adverse events continue to oc- in Canada to treat superficial ear and eye cochlear.3,4 Although ototoxicity in pa- cur. The incidence of such events is un- infections. Indications for otic prepara- tients with intact tympanic membranes known, but 20 cases have been reported tions include otitis externa6 (“swimmer’s has not yet been reported, patients taking in Canada since 1981,5 with 17 involv- ear”). Preparations that include a steroid the drug for chronic otitis media often ing vestibular disorders and 3 involving (e.g., betamethasone) are indicated for systemically absorb detectable levels of hearing loss. In most cases the condi- acute otitis externa, eczematoid dermati- the drug.11 Thus, it may be appropriate tions being treated were middle-ear dis- tis, seborrheic dermatitis and contact to warn all patients taking gentamicin ear orders with otorrhea; in 1 case genta- dermatitis with secondary infection6 and drops of possible ototoxic effects. When micin ear drops were being given to are often prescribed for off-label use to a topical agent is required in patients treat Ménière’s disease (along with treat chronic suppurative otitis media.7 with a perforated tympanic membrane, high-dose intratympanic gentamicin in- Prolonged use of these combination top- non-ototoxic ear drops such as ciproflox- fusions). Six patients had used the drops ical agents can result in a secondary fun- acin solution may preferable. for no more than 5–7 days. The dam- gal infection and mycelial plug,7 and use of any gentamicin ear drops can lead to Eric Wooltorton the development of aminoglycoside- CMAJ Editorial Fellow resistant organisms.8 Canadian Adverse Although the risk of ototoxic effects References Reaction Newsletter from aminoglycoside otic preparations 1. Important safety information: Garasone/ 9 Garamycin [Dear Healthcare Professional Let- has long been recognized, its impor- ter]. Pointe-Claire (QC): Schering Canada Inc.; Bulletin canadien tance may have previously been under- 2002 May 30. Available: www.hc-sc.gc.ca/hpb-dgps /therapeut/htmleng/adviss_ind_e.html (accessed des effets indésirables appreciated. In a survey of 2235 oto- 2002 June 13). laryngologists in the early 1990s, 84% 2. Hélal A. Aminoglycoside ear drops and ototoxic- To receive the Newsletter and health reported using ototopical agents in the ity. Can ADR Newsl 1997;7(2):3. (Also in CMAJ product Advisories by email, join Health 1997;156[7]:1056.) Canada’s Health_Prod_Info mailing list. presence of a perforated tympanic 3. Marais J, Rutka JA. Ototoxicity and topical ear membrane, and only 3.4% reported drops. Clin Otolaryngol 1998;23(4):360-7. Go to www.hc-sc.gc.ca/hpb-dgps 4. Bath AP, Walsh RM, Bance ML, Rutka JA. Oto- /therapeut/htmleng/adr.html having witnessed irreversible ear dam- toxicity of topical gentamicin preparations. and click on "subscribe." age caused by such agents.10 Laryngoscope 1999;109:1088-93. 5. Stockwell M. Gentamicin ear drops and ototoxic- Inscrivez-vous à la liste ity: update. Can Adverse Drug Reaction Newsl 2001; What to do: Acute and uncomplicated 11(1):3-4. (Also in CMAJ 2001;164[1]:93-4.) Info_Prod_Santé de Santé Canada 6. Garamycin Ophthalmic/Otic Preparations and pour recevoir par courriel le Bulletin et otitis externa is often prevented with a Garasone Ophthalmic/Otic Preparations. In: Com- les Avis au sujet des produits de santé. few drops of vinegar in each ear after pendium of Pharmaceuticals and Specialties; Ottawa: Canadian Pharmacists Association; 2002. p. 686-7. Rendez-vous à l’adresse swimming and can be treated with an an- 7. Ontario Anti-infective Review Panel. Anti-infec- www.hc-sc.gc.ca/hpb-dgps/therapeut tiseptic solution such as aluminum active guidelines for community-acquired infections. /htmlfrn/adr.html et cliquez sur 7 2nd ed. Toronto: Publications Ontario; 2001. etate. When gentamicin ear drops are 8. Clayton MI, Osborne JE, Rutherford D, Rivron RP. « abonnement ». indicated otoscopic examination is essen- A double-blind, randomized, prospective trial of a tial, because aminoglycoside ear drops topical antiseptic versus a topical antibiotic in treat- Report adverse reactions toll free to ment of otorrhea. Clin Otolaryngol 1990;15:7-10. Health Canada • Signaler sans frais des are contraindicated in patients with a 9. Morizono T, Johnstone BM Ototoxicity of topi- effets indésirables à Santé Canada perforated tympanic membrane (includ- cally applied gentamicin using a statistical analysis of electrophysiological measurement. Acta Oto- Tel./Tél. : 866 234-2345 ing those with tympanostomy tubes). laryngol 1975;80:389-93. Fax/Téléc. : 866 678-6789 The treatment duration should be as 10. Lundy LB, Graham MD. Ototoxicity and ototopical medications: a survey of otolaryngolo- Email/Courriel: [email protected] short as possible, often less than 7 days, gists. Am J Otol 1993;14:141-6. and the drug should be stopped immedi- 11. Lancaster JL, Mortimore S, McCormick M, Hart CA. Systemic absorption of gentamicin in the ately if ototoxic symptoms develop. Pa- management of active mucosal chronic otitis me- tients should be assessed for adverse ef- dia. Clin Otolaryngol 1999;24(5):435-9.

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