What is the recommended initial intravenous (IV) dose of Ativan (lorazepam) for an adult patient?

Recommended Initial IV Lorazepam Dose for Adults

For adult patients, the recommended initial intravenous dose of lorazepam (Ativan) is 2 mg total or 0.044 mg/kg (whichever is smaller), administered slowly at a rate not exceeding 2 mg per minute. 1

Dosing by Clinical Indication

Status Epilepticus

• The standard dose is 4 mg IV given slowly at 2 mg/min for patients 18 years and older 1
• If seizures continue or recur after a 10-15 minute observation period, an additional 4 mg may be administered slowly 1
• Underdosing (less than 4 mg) significantly increases progression to refractory status epilepticus (87% vs 62%, p=0.03), supporting the full 4 mg recommendation 2
• The 4 mg dose should not be reduced in patients over 40 kg, as lower doses are associated with worse seizure control 2

Sedation and Anxiolysis (Preanesthetic/Procedural)

• Initial dose: 2 mg total or 0.02 mg/lb (0.044 mg/kg), whichever is smaller 1
• This dose suffices for most adults and ordinarily should not be exceeded in patients over 50 years of age 1
• For enhanced amnesia when beneficial, doses up to 0.05 mg/kg (maximum 4 mg total) may be administered 1
• Administer 15-20 minutes before the anticipated procedure for optimum effect 1

Administration Guidelines

Rate and Preparation

• Never exceed 2 mg per minute injection rate 1
• Must be diluted with an equal volume of compatible solution (Sterile Water, Normal Saline, or 5% Dextrose) immediately prior to IV use 1
• Mix thoroughly by gently inverting—do not shake vigorously to avoid air entrapment 1
• May be injected directly into a vein or into existing IV tubing 1

Special Population Considerations

• Elderly patients (>50 years): Use the lower end of dosing (2 mg or less); do not exceed standard initial doses 1
• Patients on valproate or probenecid: Reduce lorazepam dose by 50% due to drug interactions 1
• Renal disease: No acute dose adjustment needed, but exercise caution with frequent dosing over short periods 1
• Hepatic disease: No dosage adjustment required 1

Critical Safety Considerations

Respiratory Monitoring

• Respiratory depression is the primary risk, especially when combined with opioids or other sedatives 3, 4
• Apnea may occur up to 30 minutes after the last dose 3
• Have oxygen, airway management equipment, and artificial ventilation readily available 1
• Monitor oxygen saturation continuously 5

Onset and Duration

• IV lorazepam has a latent period of 8-15 minutes, with peak effects at 15-30 minutes—this differs from diazepam which peaks in 2-3 minutes 6
• Duration of effect is 15-80 minutes, though anticonvulsant activity may be more prolonged 3
• This delayed onset means you must wait adequately before redosing to avoid stacking effects 6

Reversal Agent Availability

• Flumazenil (0.2 mg IV initial dose in adults) can reverse life-threatening respiratory depression 3
• However, flumazenil will also reverse anticonvulsant effects and may precipitate seizures—use with extreme caution in seizure patients 3, 5
• Contraindicated in tricyclic antidepressant overdose 3

Common Pitfalls to Avoid

• Underdosing in status epilepticus: Using less than 4 mg significantly worsens outcomes; always use the full recommended dose in patients >40 kg 2
• Injecting too rapidly: Exceeding 2 mg/min increases risk of apnea and cardiovascular effects 1
• Inadequate waiting period: Not allowing 10-15 minutes between doses in status epilepticus or 15-20 minutes for procedural sedation leads to dose stacking 1, 6
• Failing to dilute: IV lorazepam must be diluted 1:1 before administration 1
• Combining with other CNS depressants without dose reduction: When used with opioids or other sedatives, reduce lorazepam dose accordingly 3, 1