Severe Anaphylaxis From Remimazolam in a Mastocytosis Cancer Patient: A Case Report

Remimazolam besylate is a novel, rapid-onset, ultra-short-acting benzodiazepine with an advantageous cardio-respiratory safety profile. To date, there have been few published reports of remimazolam-induced anaphylaxis, none of which are documented in patients with mast cell disease. We describe the case of a 77-year-old male with oncologic mastocytosis who developed anaphylaxis following remimazolam administration. Symptoms included shortness of breath, hypoxia, loss of consciousness, tachycardia, and hypotension. Resolution of symptoms was attained after the administration of flumazenil, dexamethasone, diphenhydramine, famotidine, and phenylephrine. Suspicion of an anaphylactic reaction was confirmed by elevated serum tryptase levels. This case report helps establish how to diagnose anaphylaxis in a mastocytosis patient.