What is the intravenous (IV) form of Lamictal (lamotrigine)?

Lamotrigine Does Not Have an IV Formulation for Clinical Use

According to the 2014 clinical guidelines, lamotrigine (Lamictal) does not have an intravenous (IV) formulation available for clinical use. 1

Available Formulations of Lamotrigine

Lamotrigine is only available in oral formulations for clinical practice:

• Oral tablets: Available in various strengths (50 mg, 100 mg, 300 mg)
• Oral suspension: Can be used when tablet administration is not feasible
• Loading dose strategy: For patients previously on lamotrigine, a single oral loading dose of 6.5 mg/kg can be considered if they've been on the medication for >6 months without history of rash and have been off lamotrigine for <5 days 1

Important Clinical Considerations

Limitations of Oral Administration

• During emergencies when a patient cannot take oral medications, clinicians must consider alternative antiepileptic medications that do have IV formulations
• According to the clinical guideline table, alternative antiepileptic drugs with IV formulations include:
  • Levetiracetam (Keppra)
  • Valproate (Depacon)
  • Phenytoin/Fosphenytoin
  • Lacosamide (Vimpat) 1

Research Context

While a research study from 2014 developed a stable-labeled IV formulation of lamotrigine for pharmacokinetic studies, this was specifically for research purposes and not for clinical use 2. This experimental formulation used:

• A 50 mg dose of stable-labeled lamotrigine
• Complexed with 2-hydroxypropyl-β-cyclodextrin
• Was tested in only 20 patients with epilepsy
• Was not developed for commercial clinical use

Safety Considerations with Lamotrigine

• Lamotrigine carries a risk of serious rash, including Stevens-Johnson syndrome 1
• Oral loading should only be considered in patients previously on lamotrigine without history of rash
• The medication typically requires slow titration over 6 weeks to minimize rash risk 3

Clinical Alternatives When IV Administration Is Needed

If a patient requires IV antiepileptic therapy, the following alternatives should be considered:

1. Levetiracetam: IV loading safe up to 60 mg/kg; well-tolerated with minimal side effects 1
2. Valproate: Up to 30 mg/kg IV at maximum rate of 10 mg/kg/min 1
3. Fosphenytoin: 18 PE/kg IV at maximum rate of 150 PE/min 1
4. Lacosamide: IV formulation available and safe, though loading doses not well studied 1

Conclusion

When IV administration of an antiepileptic is required, clinicians must select an alternative to lamotrigine as no IV formulation is commercially available for clinical use. The choice of alternative should be guided by the patient's specific seizure type, comorbidities, and medication history.