Fluvoxamine/sumatriptan interaction

Abstract

Serotonin syndrome: case report A 30-year-old woman developed serotonin syndrome following concomitant administration of fluvoxamine and sumatriptan for depression and headache, respectively [routes, duration of treatments to reaction onset not stated; not all dosages stated]. The woman presented to the emergency department with a lower limb and right-sided facial twitching. She also had a 5-day history of headaches, in resemblance to her previously experienced migraines. She was administered sumatriptan to treat the pain, 6–8 hours prior to presentation. She had no prior history of sumatriptan use and it was newly prescribed by her general practitioner. Soon after sumatriptan administration, she experienced sudden discomfort in the right leg and right arm, worsening lower limb and right-sided facial twitching, along with difficulty in speech. Prior to this occurrence, she was also administered paracetamol at home and refused the administration of any other medications. She had a history of hemiplegic migraines, paroxysmal supraventricular tachycardia and endometriosis. She also had a longstanding history of depression, and was ongoing regular treatment with fluvoxamine 100mg once every day with several other co-medications. No recent changes were reported in her fluvoxamine dose. Upon initial assessment, her HR and BP levels were high, with a Glasgow coma scale score of 15. She particularly reported a resting tremor in her right leg and arm, and diaphoretic palms. Ophthalmic analysis revealed dilated and bilaterally sluggish pupils with an ocular clonus. She exhibited bilateral lower limb hypertonicity and hyperreflexia, and also reported 6 to 7 beats of inducible clonus in both her ankles. An initial ECG indicated sinus tachycardia with the QT interval falling below the treatment line on a QT nomogram. Based on her clinical findings and longstanding history of fluvoxamine use, a diagnosis of serotonin syndrome secondary to pharmacokinetic interaction of fluvoxamine and sumatriptan was made. The woman was admitted and put on telemetry. Following that, she was treated with cyproheptadine, IV fluids, unspecified serotonin antagonists, and an unspecified anti-histamine. Her sumatriptan and fluvoxamine doses were withheld. She was kept overnight in the short-stay unit of the emergency department under continuous observation. During her hospitalisation, periodic assessments reported significant improvement in the lower limb and ocular clonus, motor symptoms, serotonergic symptoms, and agitation. During the morning review, the clonus and tremor resolved, and her condition returned to baseline. The neurological reexamination was completely normal with a mild residual hyperreflexia in the lower limb. Eventually, her symptoms completely resolved. She was discharged with the instructions to avoid the use of concomitant triptan medications in the future and to also withhold fluvoxamine for the next 24 hours.