Is diazepam or lorazepam the most effective benzodiazepine for use in paramedic management of convulsive seizures in adults?

Managing prolonged seizures in the pre-hospital setting is an undertaking that presents significant challenges to clinicians. Patients can present with airway and breathing compromise, transport can be dangerous and there is the potential for refractory (medication resistant) status epilepticus, which has been shown to become more likely as ‘onset to drug’ time increases (Goodkin and Kapur, 2003).

Medications of the benzodiazepine class are psychoactive, all acting to increase the effect of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). Pertinent to pre-hospital care is the potent anti-convulsant effect of these medications, the efficacy of which varies across different formulations, which are further categorised depending on their duration of action.

National Ambulance Service guidelines stipulate that the first-line paramedic-led treatment for generalised seizures lasting in excess of 5 minutes should be 10 mg of intravenous diazepam, with the per rectum (PR) route considered where intravenous (IV) access is difficult (Joint Royal Colleges Ambulance Liaison Committee, 2016). Diazepam is known to be effective in the termination of seizures in 50% to 80% of cases (Treiman, 1989), although the drug redistributes into adipose tissue quickly, and as such has a short duration of action of approximately 20 minutes (Greenblatt and Divoll, 1983). In addition, it has been shown that seizure recurrence occurs in up to 50% of patients, leading to the administration of repeat diazepam doses (Cock, 2002).