Midazolam Pharmacokinetics and Administration

Pharmacokinetics and Dosing

Midazolam has a rapid onset of action and shorter duration of effect compared to diazepam, with onset within 1-2 minutes and peak effect within 3-4 minutes 1
For seizures, intramuscular midazolam can be administered at 0.2 mg/kg (maximum: 6 mg per dose) and may be repeated every 10-15 minutes 2
When using midazolam for refractory status epilepticus, a loading dose of 0.15-0.20 mg/kg followed by continuous infusion may be required 2

Midazolam clearance is reduced in the elderly, obese, and those with hepatic or renal impairment, so dose adjustments may be necessary in these populations 1
Be prepared to provide respiratory support regardless of administration route, as there is an increased incidence of apnea when midazolam is combined with other sedative agents 2
Monitor oxygen saturation during and after administration 2
Flumazenil may be administered to reverse life-threatening respiratory depression caused by midazolam; however, it will also reverse the anticonvulsant effects and may precipitate seizures 2

For an actively seizing patient when IV access is not immediately available, administer intramuscular midazolam 0.2 mg/kg (maximum 10 mg) as the first-line IM agent, as recommended by the World Health Organization guidelines 3, 4

IM diazepam should be avoided entirely because WHO guidelines explicitly state that "intramuscular administration of diazepam is not recommended because of erratic absorption" 3, 4
IM phenobarbital is only considered when rectal diazepam is not possible due to medical or social reasons, making it a distant second choice, with slower onset and higher risk of respiratory depression compared to midazolam 3, 4