mrcem2-1240

A 42-year-old man has been brought into the Emergency Department, 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. His vital signs are as follows: HR 92, BP 120/70, SaO2 98% on high flow oxygen, temperature is 36.8°C. His blood glucose level is 1.5 mmol/L, and he has an intravenous line in place.
Which of the following medications would be most appropriate to administer next?