Adverse effects of a single dose of gentamicin

We write concerning imperfections in the description of vestibular aspects of gentamicin ototoxicity in the article by Hayward et al. on single‐dose gentamicin toxicity 1. The authors failed to notice our recent article on 103 patients with gentamicin vestibulotoxicity 2, 6 of whom had just a single dose. Moreover, their summary “there were no cases of ototoxicity reported in patients receiving gentamicin.” is dangerously misleading. We can only surmise they mean no cases of cochleotoxicity—which is correct. As we point out in our article, in humans, gentamicin is selectively vestibulotoxic. A recent clinical example: a previously healthy 72‐year‐old man presented to us last week about loss of balance. He said he could still get about but no longer felt safe walking downstairs—he had several falls and has had to give up almost all his pastimes, beach‐fishing, golf, dancing etc requiring balance. He said his vision jiggles when he walks so that he can't read signs in the street unless he stops. His hearing is unchanged. This unfortunate state of affairs followed an uneventful knee replacement 2 years ago during which the thoughtful anaesthetist gave him a prophylactic dose of 240 mg IV gentamicin. It worked—the prosthesis did not become infected. Video head impulse testing now shows severe bilateral loss of semicircular function affecting the lateral more than the vertical canals. Audiogram shows an age‐related hearing loss unchanged from 3 years ago. In about half of our patients, gentamicin was given for an indication for which other safer antibiotics would have been appropriate. Four of the cases were litigated, only one came to trial but was settled before verdict for a 7‐figure sum (in Australian dollars). We have not come across any case of gentamicin vestibulotoxicity where the prescriber made the diagnosis. Those using gentamicin still fail to understand that systemic gentamicin in therapeutic doses is exclusively vestibulotoxic in humans—and can be after a single dose. These patients do not lose hearing but their balance. If they are bedbound when they receive gentamicin, they will not know about vestibulotoxicity until they try to walk. While gentamicin vestibulotoxicity is rare, it is unpredictable and devastating, especially in the elderly. As with most drugs the risk must match the benefit—the punishment must fit the crime. If the patient might have gram‐negative septicemia, then he should have gentamicin. If the patient is having an elective joint replacement or cystoscopy, he should not. To restore balance, we restate the conclusion of our previous paper: “Gentamicin ototoxicity is vestibular, not cochlear, producing permanent loss of balance, but not of hearing. Gentamicin can be vestibulotoxic in any dose, in any regimen, at any serum level.”

Competing Interests

There are no competing interests to declare.

Halmagyi, G. M. , and Curthoys, I. S. (2018) Adverse effects of a single dose of gentamicin. Br J Clin Pharmacol, 84: 2936 10.1111/bcp.13667.