FCEM2-1221

A 42-year-old man has been brought into the Emergency Department (ED) experiencing seizures that have lasted for 40 minutes before his arrival. On arrival, he is still having a tonic-clonic seizure. He is a known epileptic and is currently taking lamotrigine for seizure prevention. He has received a single dose of rectal diazepam by the paramedics en route approximately 15 minutes ago. Upon arrival in the ED, intravenous access is established, and a dose of IV lorazepam is administered. His blood glucose level is checked and is 4.5 mmol/L.

He continues to have seizures for the next 15 minutes. Which medication should be administered next?