What is the recommended PRN (as needed) dose of Ativan (lorazepam)?

PRN Lorazepam Dosing

For acute anxiety or nausea/vomiting, administer lorazepam 0.5-1 mg PRN orally or IV, with a maximum of 4 mg per 24 hours. 1, 2

Standard PRN Dosing by Indication

Anxiety (Acute Episodes)

• Lorazepam 0.5-1 mg PRN provides immediate relief for acute anxiety 2
• Maximum daily dose: 4 mg/24 hours 2
• Can be given orally or IV every 4-6 hours as needed 3
• Onset of action occurs within minutes when given IV 2

Nausea/Vomiting (Breakthrough Treatment)

• Lorazepam 0.5-2 mg PRN every 4-6 hours 3
• Can be administered PO or IV 3
• Often used as adjunct to other antiemetics in oncology settings 3

Agitation/Delirium (Oncology/Palliative Care)

• Lorazepam 1 mg subcutaneously or IV (maximum 2 mg per dose) 1
• Use reduced doses in elderly, frail, or COPD patients 1
• Further dose reduction needed when combined with antipsychotics 1

Special Population Adjustments

Elderly or Debilitated Patients

• Start with 0.25-0.5 mg PRN 1, 4
• Elderly patients have significantly higher risk of falls, cognitive decline, and paradoxical agitation 1
• The FDA label recommends initial dosing of 1-2 mg/day in divided doses for elderly patients, adjusted as tolerated 4

Severe Liver Disease

• Initial dose 0.25 mg orally 2-3 times daily 1
• Lorazepam undergoes glucuronidation (not hepatic oxidation), making it safer than other benzodiazepines in liver disease, but dose reduction still required 1

Critical Prescribing Considerations

Why PRN Dosing Works for Lorazepam

• Unlike buspirone (which requires 2-4 weeks of continuous dosing for effect), lorazepam provides immediate anxiolytic action within minutes 2
• This makes it appropriate for PRN use, unlike scheduled-only anxiolytics 2

Common Pitfalls to Avoid

• Paradoxical agitation occurs in approximately 10% of patients 1
• Regular PRN use leads to tolerance, addiction, depression, and cognitive impairment 1
• Contraindicated in severe pulmonary insufficiency, severe liver disease, and myasthenia gravis (except moribund patients) 1
• Extreme caution with concomitant high-dose olanzapine due to reported fatalities 1

Administration Details

• Oral concentrate must be mixed with liquid or semi-solid food (water, juice, applesauce, pudding) 4
• Use only the calibrated dropper provided 4
• Consume entire mixture immediately; do not store 4
• IV administration causes less thrombophlebitis than diazepam, especially in small veins 5

Monitoring for Dependence

• When discontinuing after regular use, use gradual taper to reduce withdrawal risk 4
• If withdrawal reactions develop, pause taper or increase to previous dose level, then decrease more slowly 4