What is the recommended dose of IV lorazepam per kilogram of body weight?

IV Lorazepam Dosing Guidelines

The recommended dose of IV lorazepam is 0.05-0.1 mg/kg for status epilepticus, with a maximum of 4 mg per dose in adults and children.

Dosing by Indication

Status Epilepticus

• Adults (≥18 years): 4 mg IV given slowly (2 mg/min); may repeat once after 10-15 minutes if seizures continue 1
• Children: 0.1 mg/kg IV every 5-10 minutes (maximum: 4 mg per dose) 2, 3
  • Administer over ~2 minutes to avoid pain at IV site
  • Higher doses (0.1-0.3 mg/kg) may be needed in refractory cases 2

Sedation/Anxiolysis

• Adults: 2 mg total, or 0.02 mg/lb (0.044 mg/kg), whichever is smaller 1
  • For patients >50 years: generally should not exceed 2 mg
  • For perioperative amnesia: up to 0.05 mg/kg (maximum 4 mg)
• Children: Not FDA approved for patients <18 years 1

Psychosis with Agitation

• 0.05-0.15 mg/kg IV; may repeat hourly as needed
• Maximum single dose: 5 mg 2

Administration Considerations

IV Administration Technique

• Must be diluted with equal volume of compatible solution prior to IV use 1
• Compatible solutions:
  • Sterile Water for Injection
  • Sodium Chloride Injection
  • 5% Dextrose Injection
• Inject at rate not exceeding 2 mg/minute 1
• For status epilepticus: administer over ~2 minutes to reduce pain at injection site 2

Special Populations

• Elderly: No dosage adjustment needed 1
• Hepatic disease: No dosage adjustment needed 1
• Renal disease: No adjustment needed for acute dosing; use caution with frequent dosing 1
• Drug interactions:
  • Reduce dose by 50% when coadministered with probenecid or valproate 1
  • May need to increase dose in females taking oral contraceptives 1

Monitoring and Safety

Respiratory Monitoring

• Increased risk of apnea when:
  • Given rapidly IV
  • Combined with other sedative agents 2
• Monitor oxygen saturation and respiratory effort
• Be prepared to support ventilation
• Flumazenil may be administered to reverse life-threatening respiratory depression, but may counteract anticonvulsant effects and precipitate seizures 2

Efficacy Considerations

• For status epilepticus: underdosing (<4 mg in adults) is associated with significantly higher rates of progression to refractory status epilepticus (87% vs 62%, p=0.03) 3
• Therapeutic plasma concentrations (>30 ng/ml) are maintained for at least 8 hours after a 0.1 mg/kg dose 4

Clinical Pearls

• Lorazepam has a longer duration of anticonvulsant activity compared to diazepam, making it preferred for status epilepticus 2
• Bioavailability is excellent across routes (IV, IM, oral, sublingual) at approximately 90-100% 5, 6
• Elimination half-life ranges from 8-25 hours 5
• When IV access is unavailable, rectal administration (0.5 mg/kg up to 20 mg) may be used, though absorption can be erratic 2

Remember that appropriate monitoring of vital signs and respiratory status is essential when administering IV lorazepam, and equipment for respiratory support should be immediately available.