To the Editor: Linezolid is the first of a new class of oxazolidinone antibacterials which was first registered in Australia in September 2001. It represents an important advance in the treatment of infections caused by some enterococci resistant to vancomycin and staphylococci resistant to methicillin.1 In clinical trials, the most commonly reported drug-related adverse events which led to discontinuation of linezolid therapy were headache, diarrhoea, nausea and vomiting.2 We describe a patient who developed peripheral and optic neuropathy while being treated with linezolid.

A 76-year-old man was hospitalised in November 2000 for the third revision of a left total hip joint prosthesis. This was complicated by infection with methicillin-resistant Staphylococcus aureus (MRSA) isolated from hip joint washout. The organism was sensitive to vancomycin, teicoplanin, rifampicin and fusidic acid, and resistant to ciprofloxacin. Vancomycin therapy was commenced, but had to be replaced by rifampicin and fusidic acid when the patient developed fever (40°C), rigors, rash and eosinophilia. However, the patient developed severe, generalised pruritus. Therapy with rifampicin and fusidic acid was ceased and oral linezolid (600 mg twice daily) was given.

Linezolid was initially well tolerated. However, about six months after starting treatment with the antibiotic, the patient presented to his general practitioner with numbness of his hands, feet and legs below the knee, intermittent sharp pain in both feet and blurred vision. He was hospitalised and linezolid therapy ceased. On admission, peripheral sensory loss in a glove-and-stocking distribution was noted. Nerve-conduction studies showed severe sensory-motor axonal neuropathy, more severe in the lower limbs than the upper limbs. Formal visual field testing showed patchy field damage, suggestive of drug-induced toxicity.

The patient declined further ophthalmological review. Five months after he stopped taking linezolid, he reported subjective resolution of visual impairment, but the peripheral neuropathy persists. The patient's alcohol intake had been negligible. Ongoing medications include digoxin, irbesartan, frusemide, omeprazole, piroxicam and diazepam.

We are not aware of any published articles describing peripheral or optic neuropathy associated with linezolid therapy. This information was not included in the original product information, but has been added to the revised version under the heading "Post-marketing surveillance".3

Up to June 2002 there had been only 13 reports of adverse reactions to linezolid to the Australian Adverse Drug Reactions Advisory Committee (ADRAC). Four of these, including our report, describe peripheral neuropathy and involve adult males who had received 1.2 g of linezolid daily for six to nine months. No patient's neuropathy had resolved at the time of reporting. Moreover, linezolid was the sole suspected drug in all four reports. It is important to note that the maximum duration of treatment with linezolid in clinical trials has been 28 days. Reports of neuropathy received by the manufacturer have primarily involved patients treated for longer than 28 days.3

Our report highlights the importance of postmarketing surveillance and reporting of adverse drug reactions, especially when a drug is used outside original indications or duration.