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Difficulty: HardPsychopharmacology and Psychological Therapies

Match each acute medication-induced psychiatric emergency or toxidrome with its most appropriate specific therapeutic intervention.

  • A patient being treated for depression develops tachycardia, diaphoresis, hyperreflexia, and spontaneous myoclonus shortly after taking over-the-counter dextromethorphan.Cyproheptadine administration
  • A patient with a history of psychosis presents with profound 'lead-pipe' muscle rigidity, extreme hyperthermia, and a creatine kinase level of 5,500 U/L.Bromocriptine or dantrolene administration
  • A patient managed for bipolar disorder develops severe ataxia, coarse tremors, altered mental status, and a seizure two days after starting hydrochlorothiazide.Urgent hemodialysis
  • A patient with treatment-resistant depression is brought in after an intentional overdose; ECG reveals a QRS duration of 145 msec alongside dry mucous membranes and mydriasis.Intravenous sodium bicarbonate
  • A patient taking a medication for atypical depression experiences a sudden, severe throbbing headache and a blood pressure of 215/120 mm Hg after consuming a large amount of aged cheese.Intravenous phentolamine

Answer

The clinical vignettes describe classic psychopharmacological emergencies. The dextromethorphan-precipitated hyperreflexia matches Serotonin Syndrome, treated with cyproheptadine. The 'lead-pipe' rigidity describes NMS, treated with bromocriptine or dantrolene. Thiazide-induced ataxia and seizures indicate severe lithium toxicity, necessitating hemodialysis. The anticholinergic toxidrome with widened QRS identifies TCA overdose, requiring sodium bicarbonate. Finally, the cheese-induced hypertensive emergency represents an MAOI crisis, treated with phentolamine.
Each patient presentation maps to a specific pathophysiological mechanism caused by psychiatric medication toxicity, requiring targeted antidotal therapy. Serotonin syndrome is mediated by excess 5-HT and responds to the antagonist cyproheptadine. NMS results from central dopamine blockade, responding to dopamine agonists. Severe lithium toxicity with neurologic collapse requires rapid removal via hemodialysis. TCA-induced cardiotoxicity relies on sodium channel blockade, which is overcome by the alkaline sodium load of sodium bicarbonate. MAOI tyramine crisis causes excessive alpha-adrenergic stimulation, which is blocked by phentolamine.

Step-by-Step Solution

1
Analyze the first scenario featuring hyperreflexia and myoclonus following dextromethorphan use.
Diagnosis is Serotonin Syndrome. Dextromethorphan has serotonergic activity and can trigger this syndrome when combined with antidepressants.
Identifying the specific neuromuscular findings (hyperreflexia, myoclonus) differentiates this from NMS and directs treatment toward a 5-HT2A antagonist.
2
Analyze the second scenario featuring 'lead-pipe' rigidity, hyperthermia, and elevated CK.
Diagnosis is Neuroleptic Malignant Syndrome. The profound rigidity and high CK are hallmarks of D2 receptor blockade toxicity.
Recognizing dopamine blockade as the pathophysiology points toward dopamine agonists (bromocriptine) or muscle relaxants (dantrolene) as the correct intervention.
3
Evaluate the third scenario featuring ataxia, coarse tremors, and seizures triggered by a thiazide diuretic.
Diagnosis is severe lithium toxicity. Thiazides decrease lithium clearance, leading to accumulation. The presence of seizures indicates severe, life-threatening toxicity.
While mild lithium toxicity may be managed with hydration, severe neurological symptoms or levels >4.0 mEq/L mandate urgent hemodialysis.
4
Examine the fourth scenario showing anticholinergic signs (dry mouth, mydriasis) and a widened QRS complex.
Diagnosis is Tricyclic Antidepressant (TCA) overdose. The widened QRS is caused by fast sodium channel blockade in the myocardium.
Sodium bicarbonate increases serum pH and extracellular sodium concentration, effectively overcoming the sodium channel blockade and preventing deadly arrhythmias.
5
Assess the final scenario of sudden severe hypertension and headache after eating aged cheese.
Diagnosis is a tyramine-induced hypertensive crisis in a patient taking an MAOI for atypical depression.
Excess tyramine acts as a sympathomimetic. Alpha-adrenergic blockade with phentolamine is the specific antidote for this life-threatening vasoconstriction.

Key Concept

Diagnosis and management of life-threatening psychopharmacological toxicities and drug-drug interactions.
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Topics

Psychopharmacology and Psychological Therapies

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