What PRN (pro re nata) order should be prescribed for a patient with chronic seizures?

PRN Seizure Orders for Patients with Chronic Seizures

For patients with chronic seizures, order lorazepam 0.1 mg/kg IV/IM (maximum 4 mg per dose) as the first-line PRN medication, with the option to repeat once after 5-10 minutes if seizures continue. 1

First-Line PRN Medication

The evidence strongly supports benzodiazepines as the cornerstone of acute seizure management. When IV access is available, lorazepam is preferred over diazepam due to its longer duration of action and more reliable efficacy 1. The WHO guidelines explicitly state that "if available, lorazepam is preferred over diazepam" for IV administration 1.

Dosing Specifications:

• Lorazepam: 0.1 mg/kg IV/IM (maximum 4 mg per dose)
• May repeat once after 5-10 minutes if seizure activity persists
• Have respiratory support equipment immediately available

Alternative Routes When IV Access Unavailable

If the patient lacks IV access during a seizure:

• Midazolam IM: 0.2 mg/kg (maximum 6 mg per dose), may repeat every 10-15 minutes 2
• Diazepam rectal: Standard dosing per weight (note: IM diazepam is NOT recommended due to erratic absorption) 1

The pediatric emergency guidelines note that midazolam IM has good evidence for pre-hospital/home settings 2, making it a practical option for patients with difficult IV access.

Second-Line PRN Considerations

If seizures continue after two doses of benzodiazepines, your PRN orders should include instructions to:

1. Call for immediate physician evaluation - this is no longer simple breakthrough seizure management
2. Consider the patient is entering status epilepticus territory (>5 minutes of continuous seizure activity)
3. Prepare for second-line agents, which require physician direction and typically include:
   • Levetiracetam 30 mg/kg IV (up to 3000 mg) 3
   • Valproate 30 mg/kg IV 3
   • Fosphenytoin 20 mg PE/kg IV 3

Critical Safety Parameters

Your PRN order MUST include these safety specifications:

• Monitor oxygen saturation continuously
• Have bag-valve-mask and suction immediately available
• Be prepared to provide respiratory support - benzodiazepines carry significant risk of respiratory depression, especially when combined with other sedatives 2
• Document time of seizure onset (or last time patient seen normal) - this is essential for determining if status epilepticus is developing 4

Common Pitfall to Avoid:

Do NOT order standing PRN antiseizure medications (like levetiracetam, phenytoin, or valproate) for routine breakthrough seizures in patients already on maintenance therapy 5. The 2026 AAN guidelines explicitly state that clinicians "should not prescribe benzodiazepines or antiseizure medications for patients with functional seizures without co-occurring epilepsy or another indication" 5. While this addresses functional seizures specifically, the principle applies: PRN antiseizure medications beyond benzodiazepines should be reserved for true status epilepticus, not routine breakthrough seizures.

Practical Order Set Example:

For breakthrough seizures lasting >2 minutes:

1. Lorazepam 0.1 mg/kg IV/IM (max 4 mg) x 1 dose
2. If seizure continues after 5 minutes, repeat lorazepam 0.1 mg/kg IV/IM (max 4 mg) x 1 dose
3. If seizure continues after second dose, notify physician immediately - patient requires evaluation for status epilepticus and second-line therapy

Alternative if no IV access:

• Midazolam 0.2 mg/kg IM (max 6 mg), may repeat every 10-15 minutes x 1 additional dose

Required monitoring:

• Continuous pulse oximetry during and for 1 hour after benzodiazepine administration
• Respiratory support equipment at bedside
• Document seizure onset time

This approach balances rapid, evidence-based treatment with appropriate safety guardrails and clear escalation pathways when simple PRN management is insufficient.