Can Lorazepam Be Given Intramuscularly?
Yes, lorazepam can be administered intramuscularly and is FDA-approved for this route, with rapid and complete absorption making it a preferred benzodiazepine for IM use in acute agitation and seizure management. 1
FDA-Approved IM Administration
- Lorazepam IM is FDA-approved for preanesthetic use at doses of 0.05 mg/kg up to a maximum of 4 mg, administered at least 2 hours before the anticipated procedure for optimum effect. 1
- The FDA label explicitly states that IM lorazepam should be injected deep into the muscle mass when given undiluted. 1
- For status epilepticus specifically, the FDA notes that IM lorazepam is not the preferred route because therapeutic levels may not be reached as quickly as with IV administration, though it may prove useful when an intravenous port is not available. 1
Clinical Advantages Over Other Benzodiazepines
- Lorazepam is preferred over diazepam for IM administration because it has fast onset of action, rapid and complete absorption, and no active metabolites, whereas diazepam has erratic absorption when given IM and should NOT be used via this route. 2, 3
- The American Academy of Pediatrics recommends an IM dose of 0.2 mg/kg (maximum 6 mg per dose) for seizure management when IV access is unavailable, which can be repeated every 10-15 minutes. 4
- Pharmacokinetic studies demonstrate that IM lorazepam reaches peak plasma levels at approximately 1.15 hours with an absorption half-life averaging 14.2 minutes and absolute bioavailability of 95.9%. 5
Use in Acute Agitation
- For management of acutely agitated patients, the combination of a benzodiazepine IM (including lorazepam) and an antipsychotic is frequently recommended by experts for children and adolescents. 2
- Systematic review evidence shows that 577 patients have been treated with lorazepam IM 2-4 mg in psychiatric settings, with benzodiazepines being less likely to cause treatment-emergent side effects compared to antipsychotics. 6
Critical Safety Considerations
- Equipment necessary to maintain a patent airway should be immediately available prior to IM administration of lorazepam, as respiratory depression can occur. 1
- Respiratory support must be immediately available regardless of route, with continuous monitoring of oxygen saturation, especially when combined with other sedatives. 4
- The American Academy of Pediatrics warns that both lorazepam and diazepam can cause respiratory depression, particularly when combined with other sedatives or opioids. 7
Common Pitfall to Avoid
- Do NOT confuse lorazepam with diazepam for IM use - this is a critical distinction as IM diazepam has erratic absorption and can cause tissue necrosis, making it inappropriate for this route. 3