What can I start as a prn (pro re nata) medication for a geriatric dementia patient who exhibits aggressive and violent behavior?

PRN Medication for Aggressive and Violent Behavior in Dementia

For acute, severe aggression with imminent risk of harm, use low-dose haloperidol 0.5-1 mg orally or subcutaneously as the first-line PRN medication, with a maximum of 5 mg daily, only after non-pharmacological interventions have failed or are impossible in the emergency situation. 1

Critical Prerequisites Before Any PRN Medication

Before reaching for a PRN medication, you must systematically rule out and treat reversible medical causes that commonly drive aggressive behavior in dementia patients who cannot verbally communicate discomfort 1, 2:

• Pain assessment and management - This is the single most common contributor to behavioral disturbances and must be addressed first 1
• Infections - Check for urinary tract infections and pneumonia, which frequently trigger aggression 1
• Metabolic issues - Evaluate for hypoxia, dehydration, constipation, and urinary retention 1
• Medication review - Discontinue all anticholinergic medications (diphenhydramine, oxybutynin, cyclobenzaprine) that worsen agitation 1

PRN Medication Algorithm

First-Line PRN: Haloperidol

Haloperidol 0.5-1 mg orally or subcutaneously is the preferred PRN antipsychotic for acute severe aggression in geriatric dementia patients. 1

Dosing specifics:

• Start with 0.5 mg in frail elderly patients 1
• Can repeat every 2 hours as needed 1
• Maximum 5 mg total daily in elderly patients 1
• Use lower doses (0.25-0.5 mg) and titrate gradually in very frail patients 1

Critical safety monitoring:

• ECG monitoring for QTc prolongation is necessary 1
• Monitor for extrapyramidal symptoms (tremor, rigidity, bradykinesia) 1
• Discuss increased mortality risk (1.6-1.7 times higher than placebo) with surrogate decision-makers before initiating 1, 2

Alternative PRN Options

Risperidone 0.25-0.5 mg orally can be used as an alternative PRN if haloperidol is contraindicated 1, 3:

• Lower risk of extrapyramidal symptoms compared to haloperidol 4
• Risk of extrapyramidal symptoms increases at doses above 2 mg/day 1
• Mean effective dose in trials was 0.95 mg/day 4

Olanzapine 2.5 mg orally or IM is a second-line alternative 1:

• Less effective in patients over 75 years 1
• Higher risk of oversedation and metabolic effects 1
• Reduce to 2.5 mg in elderly patients 1

What NOT to Use as PRN

Avoid benzodiazepines (lorazepam, midazolam) as first-line PRN for agitated dementia except in alcohol or benzodiazepine withdrawal 1:

• Increase delirium incidence and duration 1
• Cause paradoxical agitation in approximately 10% of elderly patients 1
• Risk of respiratory depression, tolerance, and addiction 1

Avoid anticholinergic medications (diphenhydramine) as they worsen agitation and cognitive function 1

Chronic Management Strategy (Not PRN)

If aggressive episodes are frequent and PRN medications are being used repeatedly, transition to scheduled chronic management 1, 2:

SSRIs are first-line for chronic agitation:

• Citalopram 10 mg/day (maximum 40 mg/day) 1, 2
• Sertraline 25-50 mg/day (maximum 200 mg/day) 1, 2
• Requires 4 weeks at adequate dosing to assess response 1, 2

Trazodone 25 mg/day (maximum 200-400 mg/day) is an alternative if SSRIs fail 1, 2:

• Use caution in patients with premature ventricular contractions 1
• Risk of orthostatic hypotension and falls 1

Essential Documentation and Monitoring

• Document that behavioral interventions were attempted and failed before each PRN dose 1, 2
• Use quantitative measures (Cohen-Mansfield Agitation Inventory or NPI-Q) to track severity 1
• Evaluate ongoing need daily with in-person examination 1
• If PRN medications are needed more than 2-3 times weekly, transition to scheduled chronic management 1

Common Pitfalls to Avoid

• Never continue antipsychotics indefinitely - Approximately 47% of patients continue receiving antipsychotics after discharge without clear indication 1
• Never use antipsychotics for mild agitation - Reserve for severe symptoms that are dangerous or cause significant distress 1, 2
• Never skip the medical workup - Treating the underlying cause (pain, infection, constipation) is more effective than any medication 1, 2
• Never use typical antipsychotics as first-line chronic therapy - 50% risk of tardive dyskinesia after 2 years of continuous use 1