A 55-year-old man is brought by ambulance to the emergency department due to acute-onset agitation. While at work, the patient became angry during a meeting, throwing his laptop against a wall and accusing his coworkers of conspiring against him. On arrival, he is diaphoretic with flushed skin and dilated pupils. Temperature is 37.6 C (99.7 F), blood pressure is 150/90 mm Hg, pulse is 118/min, and respirations are 18/min. Physical examination shows no other abnormalities. ECG reveals sinus tachycardia and a prolonged QT interval. The patient refuses to provide a urine specimen. His voice becomes increasingly loud, and he is convinced that other patients are stealing money from him. Administration of a medication with which of the following properties is the most appropriate initial treatment?

Question

A 55-year-old man is brought by ambulance to the emergency department due to acute-onset agitation.  While at work, the patient became angry during a meeting, throwing his laptop against a wall and accusing his coworkers of conspiring against him.  On arrival, he is diaphoretic with flushed skin and dilated pupils.  Temperature is 37.6 C (99.7 F), blood pressure is 150/90 mm Hg, pulse is 118/min, and respirations are 18/min.  Physical examination shows no other abnormalities.  ECG reveals sinus tachycardia and a prolonged QT interval.  The patient refuses to provide a urine specimen.  His voice becomes increasingly loud, and he is convinced that other patients are stealing money from him.  Administration of a medication with which of the following properties is the most appropriate initial treatment?

Quizplus · Accepted Answer

This patient's acute-onset agitation, paranoia, and physical signs of adrenergic excess (eg, diaphoresis, mydriasis, hypertension, tachycardia) are consistent with stimulant intoxication. Stimulant drugs (eg, cocaine, methamphetamine, amphetamines) block monoamine transporters and, at high doses, inhibit vesicular transporters, leading to a buildup of dopamine and norepinephrine in the synaptic cleft that stimulates adrenergic receptors and produces the sympathomimetic toxidrome. Initial management of stimulant intoxication involves controlling agitation and reducing sympathetic hyperactivity with benzodiazepines, medications that enhance the inhibitory effect of GABA through positive allosteric modulation at the GABA A receptor. Benzodiazepines (eg, lorazepam) can be safely administered in repeated doses, if needed, to manage psychomotor agitation and are also effective in managing the hypertension and tachycardia caused by stimulant intoxication. Although paranoid psychosis, as seen in this patient, may occur in stimulant intoxication, antipsychotics (ie, antidopaminergic) medications are not recommended as first-line treatments due to their potential to prolong the QT interval, lower the seizure threshold, and interfere with heat dissipation (Choice B). (Choice A) Beta-adrenergic antagonists (ie, beta blockers) are relatively contraindicated in stimulant intoxication due to their theoretical ability to produce a state of unopposed alpha-adrenergic drive (ie, stimulants lead to both alpha- and beta-adrenergic receptor agonism). (Choice C) Cholinergic medications enhance or mimic the action of the neurotransmitter acetylcholine. Physostigmine is an indirect-acting cholinergic agent used as an antidote for anticholinergic toxicity. Although agitation, tachycardia, and dilated pupils are seen in anticholinergic toxicity, this toxidrome is also associated with dry skin and mucous membranes. This patient's diaphoresis makes stimulant toxicity more likely. (Choice E) Serotonergic medications (eg, selective serotonin reuptake inhibitors) are used to treat anxiety and depressive disorders. They are not effective in managing acute agitation and psychosis. Educational objective: The initial management of stimulant intoxication involves controlling agitation and reducing sympathetic hyperactivity with benzodiazepines, medications that enhance the inhibitory effect of GABA. References: Overdose of drugs for attention-deficit hyperactivity disorder: clinical presentation, mechanisms of toxicity, and management. (http://www.ncbi.nlm.nih.gov/pubmed/23757186)

A 55-Year-Old Man Is Brought by Ambulance to the Emergency