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Systemic absorption of gentamicin in the management of active mucosal chronic otitis media
J L Lancaster1, S Mortimore, M McCormick
1Department of Otolaryngology and Medical Microbiology, Royal Liverpool University Hospital, UK.
Abstract:
A prospective study was performed on patients with active mucosal chronic otitis media who were being treated with the gentamicin-containing preparation Gentisone HC. In 27 patients plasma gentamicin levels were measured. Detectable levels were found in 7/27 (26%). Pre- and post-treatment audiometry was performed on 16 patients. There was no statistically significant difference in the change of the mean bone conduction thresholds as a result of treatment, between the treatment and control ears (P = 0.07, Wilcoxon signed Ranks Test at 95% C.I.). We conclude that there is evidence of systemic absorption of gentamicin that would ultimately be absorbed into the perilymph. Gentamicin is known to be ototoxic affecting the vestibular system in lower doses and the cochlea in high doses, hence audiometric assessment is not an appropriate screen for ototoxicity when using topical gentamicin-containing drops. Alternative topical preparations should be further investigated.
Insights
Topical gentamicin in ear drops showed systemic absorption in 26% of patients with chronic otitis media. Standard hearing tests may not detect gentamicin
Area of Science:
- Otolaryngology
- Pharmacology
- Audiology
Background:
- Chronic otitis media (COM) is a common ear condition.
- Gentamicin is an antibiotic used in some topical ear preparations for COM.
- Concerns exist regarding potential ototoxicity from systemic absorption of topical gentamicin.
Purpose of the Study:
- To investigate systemic absorption of gentamicin from Gentisone HC in patients with active mucosal chronic otitis media.
- To assess the correlation between topical gentamicin use and hearing function.
- To evaluate the adequacy of audiometric screening for ototoxicity.
Main Methods:
- Prospective study design.
- Plasma gentamicin levels measured in 27 patients.
- Pre- and post-treatment audiometry conducted in 16 patients.
- Comparison of hearing thresholds between treated and control ears.
Main Results:
- Detectable plasma gentamicin levels found in 7/27 (26%) patients.
- No statistically significant difference in bone conduction thresholds between treatment and control ears (P = 0.07).
- Evidence of systemic absorption suggests potential perilymph uptake.
Conclusions:
- Topical gentamicin preparations can be systemically absorbed.
- Audiometric assessment is insufficient to screen for gentamicin ototoxicity.
- Alternative topical treatments for chronic otitis media warrant further investigation.