FDA updates potential CNS adverse reaction reports for linezolid, methylene blue

The FDA has offered a further warning that both linezolid and methylene blue may potentially have adverse interactions with certain serotonergic psychiatric medications.

Not all serotonergic psychiatric drugs have an equal capacity to cause serotonin syndrome with linezolid, according to an FDA press release. The cases from the FDA’s Adverse Event Reporting System (AERS) primarily occurred in patients taking a selective serotonin reuptake inhibitor (SSRI) or a serotonin norepinephrine reuptake inhibitor (SNRI) with linezolid. Further investigation is needed to determine whether linezolid reacts adversely to drugs with lesser degrees of serotonergic activity.

The adverse reactions to methylene blue reported to AERS occurred in the context of parathyroid surgery, which involved the IV administration of methylene blue as a visualizing agent, according to the release. Doses of methylene blue ranged from 1 mg/kg to 8 mg/kg.

Adverse reactions also were reported in cases where methylene blue was administered with SSRI, SNRI or clomipramine.

Methylene blue is not currently approved by the FDA. Limited data exist regarding its use in various settings, so it is not known whether the drug could cause serotonin syndrome when administered orally or by local tissue injection, or in IV doses lower than 1 mg/kg. It is also unclear whether IV methylene blue administration could yield an adverse reaction in other psychiatric drugs with lesser degrees of serotonergic activity.

For more information, please visit the FDA website here and here.

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