Escitalopram × Methylthioninium chloride (methylene blue)

Methylene blue (methylthioninium chloride) inhibits monoamine oxidase (MAO). The US Food and Drug Administration (FDA) escitalopram label classes intravenous methylene blue as an MAO inhibitor, and the FDA methylene blue label cites literature describing it as a potent reversible inhibitor of this enzyme. Escitalopram blocks serotonin reuptake. Together they can cause severe, sometimes fatal serotonin syndrome (methylene blue labels). No reports involved other routes of methylene blue, such as oral tablets or local tissue injection (FDA escitalopram label).

Serotonin syndrome. Mental status changes: agitation, hallucinations, delirium, coma. Autonomic signs: tachycardia, labile blood pressure, dizziness, sweating, flushing, fever. Neuromuscular signs: tremor, rigidity, myoclonus, hyperreflexia, incoordination. Seizures, nausea, vomiting and diarrhoea may occur. Some reported cases were fatal (FDA methylene blue label).

The combination is contraindicated: the US Food and Drug Administration (FDA) escitalopram label contraindicates escitalopram with MAO inhibitors and starting it in a patient who is receiving intravenous methylene blue. The methylene blue labels approved by the European Medicines Agency (EMA) and the FDA say to avoid it in patients taking selective serotonin reuptake inhibitors. If a patient on escitalopram needs methylene blue, stop escitalopram before it is given (FDA escitalopram label). When methylene blue cannot be avoided, give the lowest possible dose and observe the patient for nervous system effects for 4 hours (methylene blue labels). Monitor the ECG and blood pressure during and after the infusion (EMA methylene blue SmPC). If signs of serotonin syndrome appear, stop methylene blue and escitalopram and start supportive treatment (FDA labels of both drugs). Serotonergic drugs, escitalopram included, are not taken for 72 hours after the last methylene blue dose (FDA methylene blue label).