Metronidazole Update

The product information for Flagyl® (metronidazole) has recently been updated to include a warning regarding posterior reversible encephalopathy syndrome (PRES). This rare neurological condition has a variable presentation. Symptoms may include visual disturbances, seizures, headaches, and altered consciousness. Life-threatening complications, such as status epilepticus or cerebral haemorrhage, can occur.

There are many potential causes of this syndrome, including autoimmune disorders, eclampsia, and some medications. A recent review of antibiotic-associated PRES found that metronidazole was one of the most frequently implicated agents. While metronidazole-induced encephalopathy (MIE) has previously been described in the literature, few cases presenting as PRES have been reported. Prompt diagnosis is crucial as outcomes are generally good when appropriate treatment is started early. The Flagyl® product information now advises radiologic imaging for any patient who presents with symptoms suggestive of PRES.

Metronidazole is a commonly used antibiotic that is generally well tolerated. However, it is associated with rare and potentially serious neurotoxicity. In the past ten years, the Therapeutic Goods Administration (TGA) has received 74 reports of nervous system disorders in association with metronidazole and three reports of encephalopathy.