A 24-yeаr-оld femаle with mаjоr depressive disоrder is brought to the emergency department by her roommate. She was started on Sertraline 50mg daily two weeks ago, but her roommate notes she took "multiple pills" over the last 24 hours due to a worsening mood. Upon assessment, the patient is febrile (102.1F), tachycardic, diaphoretic, and exhibiting hyperreflexia and spontaneous clonus in her lower extremities. Which of the following pathophysiological mechanisms explains her presentation, and what is the immediate pharmacological intervention?