What is a common PRN (pro re nata) medication for agitation?

PRN Medications for Acute Agitation

For acute agitation in undifferentiated patients, use either a benzodiazepine (lorazepam 1-2 mg or midazolam) or a conventional antipsychotic (haloperidol 2-5 mg or droperidol) as effective monotherapy. 1

First-Line Options Based on Clinical Context

For Undifferentiated Agitation

• Lorazepam 1-2 mg (oral, IM, or IV) is the most versatile first-line PRN agent, effective across multiple etiologies of agitation with rapid onset and no active metabolites 1, 2
• Haloperidol 2-5 mg IM provides prompt control in acutely agitated patients with moderately severe to very severe symptoms, with subsequent doses administered as often as every hour if needed (though 4-8 hour intervals are typically satisfactory) 1, 3
• Midazolam offers more rapid onset than lorazepam but shorter duration of action 1

For Known Psychiatric Illness (Psychosis/Mania)

• Haloperidol 0.5-2 mg PRN is preferred for patients with acute mania, psychosis, delusions, or disorganized thinking, as it treats the underlying condition rather than just sedating 4, 3
• Start with 0.5-1 mg doses and titrate upward based on response, repeating hourly until symptoms are controlled 4, 3
• Antipsychotics (typical or atypical) as monotherapy are recommended for both agitation management and initial treatment when antipsychotics are indicated for the underlying psychiatric condition 1

For Cooperative Patients

• Oral lorazepam 1-2 mg plus oral risperidone 2-3 mg is effective combination therapy for agitated but cooperative patients 1
• Atypical antipsychotics (olanzapine, ziprasidone, quetiapine, risperidone) show comparable efficacy to haloperidol with lower rates of extrapyramidal side effects 1

When Rapid Sedation Is Required

• Droperidol is superior to haloperidol when rapid sedation is the priority, though concerns about QT prolongation exist despite large safety series showing minimal cardiac events in over 12,000 patients 1
• Combination therapy with parenteral benzodiazepine plus haloperidol may produce more rapid sedation than monotherapy in acutely agitated psychiatric patients 1

Pediatric Considerations

• The combination of a benzodiazepine and an antipsychotic is frequently recommended by experts for acutely agitated children and adolescents 1
• Lorazepam is preferred over other benzodiazepines due to fast onset, rapid and complete absorption, and no active metabolites 1
• Alternative agents include diphenhydramine, hydroxyzine, and clonidine, though these are less well-studied 1

Critical Pitfalls to Avoid

Benzodiazepine Monotherapy Limitations

• Avoid benzodiazepines as monotherapy for agitation secondary to mania or psychosis, as they do not treat the underlying condition and only provide sedation 4
• Benzodiazepines significantly increase fall risk and should be avoided in elderly or frail patients when possible 4
• Use lorazepam 0.25-0.5 mg only as adjunctive therapy if agitation remains refractory to antipsychotics 4, 2

Dosing Errors

• Many clinicians underdose antipsychotics for acute psychiatric agitation—haloperidol 2-5 mg IM (not 0.5 mg) is the appropriate starting range for moderate to severe agitation 3
• Lower doses (0.25-0.5 mg lorazepam, 0.5-1 mg haloperidol) are appropriate only for elderly, frail, or medically compromised patients 2

Monitoring Requirements

• Monitor for excessive sedation, especially when combining benzodiazepines with antipsychotics 2
• Watch for paradoxical agitation with benzodiazepines, which occurs in approximately 10% of patients 2
• Implement fall precautions including bedside commode, non-skid surfaces, and adequate lighting when using sedating medications 4

Drug-Specific Cautions

• Droperidol can prolong QT interval—avoid in patients with known cardiac conduction abnormalities 1
• Haloperidol carries risk of extrapyramidal symptoms and rare cardiac arrhythmias 5
• Avoid long-term regular benzodiazepine use due to tolerance, addiction, and cognitive impairment 2

Alternative Agents

• IM olanzapine 10 mg shows greater reduction in agitation at 2 hours compared to lorazepam 2 mg IM in bipolar mania, though differences disappear by 24 hours 2, 6, 5
• IM ziprasidone demonstrates significant calming effects within 30 minutes for acutely agitated patients with schizophrenia 6, 5
• Inhaled loxapine provides rapid absorption with separation from placebo as early as 10 minutes, though restricted to hospital use due to bronchospasm risk 7