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Difficulty: HardPharmacologic Interventions

A 7474-year-old man is evaluated on the inpatient medical ward for acute agitation. He was admitted 22 days ago for a complicated urinary tract infection and has been receiving intravenous ceftriaxone. His medical history is significant for Parkinson disease, for which he takes carbidopa-levodopa, and benign prostatic hyperplasia. Temperature is 37.2∘C37.2^\circ\text{C} (99.0∘F99.0^\circ\text{F}), blood pressure is 134/82 mmHg134/82\text{ mmHg}, pulse is 88/min88/\text{min}, and respiratory rate is 16/min16/\text{min}. The nursing staff reports that the patient was awake most of the night, shouting at "strangers in the room" and repeatedly attempting to pull out his peripheral intravenous catheter. On examination, the patient is disoriented to time and place, and his attention fluctuates during the interview. He has a baseline resting tremor and upper extremity cogwheel rigidity. Non-pharmacologic interventions, including frequent reorientation, optimizing room lighting, and placing a dedicated sitter in the room, have failed to calm the patient, and he remains highly combative. Which of the following is the most appropriate pharmacologic intervention to manage this patient's acute agitation?

  1. Administer oral quetiapineAnswer
  2. B
    Administer intravenous haloperidol
  3. C
    Administer intravenous lorazepam
  4. D
    Increase the dose of carbidopa-levodopa
  5. E
    Switch intravenous ceftriaxone to intravenous cefepime

Answer

Administer oral quetiapine.
The correct answer is to administer oral quetiapine. This patient is experiencing hyperactive delirium secondary to a urinary tract infection. While non-pharmacologic measures are the first-line treatment for delirium, pharmacologic intervention is indicated when the patient's agitation poses a direct threat to their safety or essential medical care (e.g., pulling out intravenous lines). In the general population, low-dose haloperidol is frequently used for severe delirium-associated agitation. However, in patients with Parkinson disease, typical antipsychotics (like haloperidol) and most atypical antipsychotics (like risperidone or olanzapine) are strictly contraindicated due to their strong dopamine (D2) receptor antagonism, which can precipitate severe extrapyramidal symptoms, profound rigidity, or an akinetic crisis. Quetiapine is the antipsychotic of choice for acute agitation in Parkinson disease because it has a very low affinity for D2 receptors and rapidly dissociates from them, providing sedative and antipsychotic effects without significantly worsening parkinsonian motor symptoms.

Step-by-Step Solution

1
Diagnose the acute condition.
The patient is experiencing delirium, characterized by fluctuating attention, disorientation, and visual hallucinations, precipitated by a urinary tract infection.
Recognizing the underlying acute process is necessary before attempting symptomatic management.
2
Determine the indication for pharmacologic intervention.
Pharmacologic management is indicated because non-pharmacologic measures (sitter, reorientation) have failed, and the patient poses an immediate danger to his medical care (pulling out IV lines).
Antipsychotics in elderly patients with delirium should be reserved only for severe agitation that poses a safety risk.
3
Identify contraindications based on the patient's comorbidities.
The patient has Parkinson disease. Typical antipsychotics (like haloperidol) and most atypical antipsychotics (like risperidone) block dopamine (D2) receptors powerfully and will severely worsen his parkinsonism.
Avoiding medications that directly antagonize the depleted neurotransmitter system in Parkinson disease prevents catastrophic motor deterioration.
4
Select the safest pharmacologic agent.
Quetiapine is selected.
Quetiapine (along with clozapine and pimavanserin) has very low affinity for D2 receptors and rapid dissociation, making it the preferred agent for acute agitation or psychosis in patients with Parkinson disease.

Key Concept

In patients with Parkinson disease who develop severe, medically refractory delirium or psychosis, low-potency atypical antipsychotics with minimal D2 receptor affinity (such as quetiapine) are the preferred pharmacologic interventions to avoid precipitating an akinetic crisis.
Estimated Time:1m 30s
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Pharmacologic Interventions

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