IV Levetiracetam Dosing for Patients on 500mg PO BID
The equivalent IV dose of Keppra (levetiracetam) for a patient taking 500mg orally twice daily is 500mg IV twice daily, administered over 15 minutes.
Rationale for Dose Equivalence
The FDA drug label for levetiracetam clearly states that when switching from oral to IV administration, the total daily dosage and frequency should remain equivalent 1. This is because:
- Levetiracetam has excellent bioavailability (>95%) when administered orally
- IV and oral formulations are bioequivalent
- No dose adjustment is needed when converting between routes
Administration Guidelines
When administering IV levetiracetam:
- Use the 500mg/100mL pre-diluted solution (5mg/mL concentration)
- Administer over 15 minutes
- Do not further dilute the solution
- Maintain the same twice-daily dosing schedule as the oral regimen
Pharmacokinetic Considerations
Levetiracetam has favorable pharmacokinetic properties that support the 1:1 conversion between oral and IV formulations:
- Minimal protein binding (<10%)
- Linear pharmacokinetics
- Not metabolized by liver cytochrome P450 enzymes
- Primarily eliminated unchanged through the kidneys (66% of dose)
- Half-life of approximately 6-8 hours in adults with normal renal function 2
Special Considerations
Renal Function
- Dose adjustment is necessary for patients with moderate to severe renal impairment 1
- No dose adjustment is needed for patients with mild renal impairment or normal renal function
Duration of IV Therapy
- IV levetiracetam should only be used temporarily when oral administration is not feasible
- Return to oral therapy as soon as possible using the same dose (500mg twice daily)
Clinical Efficacy
Levetiracetam at doses of 1000mg/day (500mg twice daily) has been shown to be effective in reducing seizure frequency compared to placebo 3, 4. While higher doses (2000-4000mg/day) may provide additional benefit for some patients, the 1000mg/day dose is appropriate for many patients and has a favorable side effect profile.
Common Side Effects
The most common adverse effects of IV levetiracetam include:
- Somnolence
- Asthenia (weakness)
- Dizziness
- Infection
These side effects are generally similar between oral and IV formulations, though the IV route may cause transient local irritation at the infusion site.
Remember that maintaining consistent therapeutic levels is crucial for seizure control, so administering the equivalent IV dose (500mg twice daily) when oral therapy is temporarily not feasible is the appropriate approach.