What are the recommended PRN (as needed) medications for a patient with agitation, considering their medical history and potential for adverse effects?

PRN Medications for Agitation in Geriatric Patients

For acute agitation in elderly patients, low-dose haloperidol (0.5-1 mg orally or subcutaneously) is the first-line PRN medication after non-pharmacological interventions have failed and only when the patient is severely agitated with risk of harm to self or others. 1

Critical First Step: Non-Pharmacological Interventions and Medical Workup

Before administering any PRN medication, you must systematically address reversible causes that commonly drive agitation in elderly patients who cannot verbally communicate discomfort: 1

• Pain assessment and management - untreated pain is a major contributor to behavioral disturbances 1
• Infections - check for urinary tract infections and pneumonia, which are common triggers 1
• Metabolic disturbances - evaluate for hypoxia, dehydration, constipation, urinary retention, and electrolyte abnormalities 1
• Medication review - identify and discontinue anticholinergic medications (diphenhydramine, oxybutynin, cyclobenzaprine) that worsen agitation 1
• Environmental modifications - ensure adequate lighting, reduce excessive noise, use calm tones with simple one-step commands 1

PRN Medication Selection Algorithm

For Severe Acute Agitation (Imminent Risk of Harm)

Haloperidol 0.5-1 mg orally or subcutaneously every 2 hours as needed, maximum 5 mg daily in elderly patients. 1, 2 The FDA label specifies that geriatric patients require lower doses with more gradual adjustments, and doses >1 mg provide no evidence of greater effectiveness while significantly increasing risk of sedation and side effects. 3

• Start with 0.25-0.5 mg in frail elderly patients and titrate gradually 1
• Haloperidol provides targeted calming without excessive sedation and has lower risk of respiratory depression compared to benzodiazepines 1, 4, 5
• Monitor ECG for QTc prolongation, as haloperidol carries risk of dysrhythmias and sudden death 1, 3
• Assess for extrapyramidal symptoms (tremor, rigidity, bradykinesia) at each administration 1

For Anxiety Without Delirium

Lorazepam 0.25-0.5 mg orally PRN, maximum 2 mg in 24 hours. 2 Lorazepam is preferred over other benzodiazepines due to its short half-life, lack of active metabolites, and predictable pharmacokinetics in elderly patients. 2

• Use the lower end of dosing (0.25 mg) in frail patients or those with COPD 2
• Critical warning: Approximately 10% of elderly patients experience paradoxical agitation with benzodiazepines 1, 2
• Benzodiazepines increase delirium incidence and duration, and should NOT be used as first-line for agitated delirium except in alcohol or benzodiazepine withdrawal 1, 2

For Patients Unable to Swallow

Midazolam 2.5 mg subcutaneously every 2-4 hours PRN for anxiety in patients unable to take oral medications. 2 Reduce dose to 5 mg over 24 hours if eGFR <30 mL/minute. 2

Second-Line PRN Options

If haloperidol is contraindicated or ineffective:

• Olanzapine 2.5-5 mg IM - use 2.5 mg in elderly patients with dementia-related agitation 2

  • Risk of oversedation and respiratory depression, especially if combined with benzodiazepines 1
  • Less likely to cause extrapyramidal symptoms than haloperidol 1
  • Never combine with benzodiazepines due to reported fatalities 2

• Quetiapine 25 mg orally PRN - second-line option with caution due to orthostatic hypotension and sedation 2

• Risperidone 0.5 mg orally PRN - alternative second-line option, reduce dose in severe renal/hepatic impairment 2

What NOT to Use

• Avoid benzodiazepines as first-line for agitated delirium - they worsen confusion, cause paradoxical agitation in 10% of elderly patients, and increase fall risk 1, 2
• Avoid typical antipsychotics other than haloperidol - 50% risk of tardive dyskinesia after 2 years of continuous use 1
• Avoid anticholinergic medications (diphenhydramine) - they worsen agitation and cognitive function 1
• Avoid combining olanzapine with benzodiazepines - risk of fatal respiratory depression 2

Critical Safety Discussion Required

Before initiating any antipsychotic PRN, discuss with the patient (if feasible) and surrogate decision maker: 1

• Increased mortality risk - 1.6-1.7 times higher than placebo in elderly dementia patients 1, 3
• Cardiovascular risks - QT prolongation, dysrhythmias, sudden death, hypotension 1
• Cerebrovascular adverse events - particularly with risperidone and olanzapine (three-fold increase in stroke risk) 1
• Falls risk - all antipsychotics and benzodiazepines significantly increase fall risk 1, 2
• Extrapyramidal symptoms - tremor, rigidity, bradykinesia with haloperidol 1

Monitoring and Reassessment

• Evaluate response after 30 minutes and again at 60 minutes using standardized scales when possible 2
• Daily in-person examination to determine ongoing need for PRN medications 1, 2
• Document effectiveness and any adverse effects after each administration 2
• Taper and discontinue as soon as the acute episode resolves - avoid inadvertent chronic use 1
• Monitor vital signs for hypotension, bradycardia, and orthostatic changes 2

Common Pitfalls to Avoid

• Do not use PRN antipsychotics for mild agitation - reserve for severe symptoms that are dangerous or cause significant distress 1
• Do not continue PRN medications indefinitely - review need at every visit and document justification for ongoing use 1
• Do not skip the medical workup - treating agitation without addressing underlying causes (pain, infection, constipation) leads to treatment failure 1
• Do not use higher than recommended initial doses - doses >1 mg haloperidol in elderly patients provide no additional benefit and significantly increase adverse effects 3
• Do not combine multiple sedating agents without careful monitoring for oversedation and respiratory depression 2