How can lorazepam be administered?

Routes of Administration for Lorazepam

Lorazepam can be administered via oral (including sublingual), intravenous, intramuscular, and subcutaneous routes, with oral and intravenous being the most commonly used in clinical practice. 1, 2

Oral Administration

Standard oral dosing is the most common route for outpatient management:

• Available as tablets or concentrated oral solution 1
• The oral concentrate must be mixed with liquid (water, juice, soda) or semi-solid food (applesauce, pudding) using the calibrated dropper provided 1
• The entire mixture should be consumed immediately and not stored for future use 1
• Typical dosing ranges from 2-6 mg/day in divided doses, with the largest dose at bedtime 1
• For anxiety: 2-3 mg/day given twice or three times daily 1
• For insomnia: single dose of 2-4 mg at bedtime 1
• Elderly or debilitated patients should start at 1-2 mg/day in divided doses 1

Sublingual administration is highly effective and well-absorbed:

• Sublingual lorazepam achieves 94-98% bioavailability, equivalent to oral tablets 3
• Peak plasma concentrations occur at approximately 2.3 hours after sublingual dosing 3
• For acute seizure emergencies, sublingual lorazepam oral concentrate solution (0.5-2 mg) effectively stops 66% of repetitive seizures and 70% of prolonged seizures within 5 minutes 4
• Sublingual administration is particularly useful when rapid absorption is needed but IV access is unavailable 3, 4

Intravenous Administration

IV lorazepam is the preferred route for acute medical emergencies:

• Available as 2 mg/mL or 4 mg/mL sterile injection 2
• For status epilepticus or convulsive seizures, IV lorazepam is preferred over diazepam when IV access is available 5
• For acute agitation, 1 mg IV (maximum 2 mg) is recommended 6
• IV administration provides immediate onset but maximum sedative effect still requires 30-40 minutes 7
• Elimination half-life after IV dosing is 12.9 hours 3

Intramuscular Administration

IM lorazepam is rapidly absorbed but has significant limitations:

• Available as 2 mg/mL or 4 mg/mL sterile injection for IM use 2
• Absorption is rapid with peak levels at 1.15 hours and absorption half-life of 14 minutes 3
• Bioavailability is 96%, essentially complete 3
• Critical caveat: IM administration causes high frequency of injection site pain and restlessness lasting 20-40 minutes, making it less desirable than oral or IV routes 7
• For preanesthetic medication, IM doses of 0.04-0.06 mg/kg are effective 8

Subcutaneous Administration

SC lorazepam is an option for palliative care settings:

• For acute agitation in palliative patients, 1 mg SC (maximum 2 mg) can be administered 6

Rectal Administration

Rectal lorazepam is NOT recommended:

• Unlike diazepam, lorazepam should not be given rectally due to erratic absorption 5
• When IV access is unavailable for seizures, rectal diazepam or IM phenobarbital should be used instead 5

Route Selection Algorithm

Choose the route based on clinical urgency and patient factors:

1. For status epilepticus/acute seizures with IV access: Use IV lorazepam 5
2. For status epilepticus without IV access: Use rectal diazepam or IM phenobarbital (NOT lorazepam) 5
3. For home treatment of prolonged/repetitive seizures: Use sublingual lorazepam oral concentrate solution 4
4. For routine anxiety management: Use oral tablets or concentrate 1
5. For acute agitation in hospital/palliative care: Use IV or SC lorazepam 6
6. For preanesthetic medication: Use oral or IM (though oral is preferred due to fewer side effects) 8, 7

Important Clinical Caveats

Avoid common pitfalls with lorazepam administration:

• Do not use IM lorazepam as first-line due to injection site pain and paradoxical restlessness 7
• Do not use rectal lorazepam—absorption is unreliable 5
• When using oral concentrate, never store the drug-liquid mixture; it must be consumed immediately 1
• Lorazepam should not be used in outpatient settings or for hospital stays <72 hours due to prolonged duration of action 8
• Sedative effects persist for at least 4 hours even with IV administration 7
• Approximately 10% of patients experience paradoxical agitation with benzodiazepines 6
• Gradual taper is required when discontinuing to avoid withdrawal reactions 1