Needle Selection for Deltoid Ativan (Lorazepam) Injection
Use a 1-1.5 inch, 22-25 gauge needle for deltoid intramuscular injection of lorazepam 0.25mg in adults.
Intramuscular Administration Considerations
Absorption and Efficacy
- Lorazepam is rapidly absorbed from deltoid intramuscular injection, reaching peak plasma concentrations within 1-3 hours, with an absorption half-life of approximately 14-21 minutes 1, 2.
- The deltoid site provides 95.9% bioavailability, which is essentially complete absorption comparable to intravenous administration 2.
Important Clinical Caveat: Pain and Adverse Effects
- Intramuscular lorazepam is associated with significant pain at the injection site and restlessness persisting for 20-40 minutes 3.
- This pain and discomfort may more than offset any advantage of faster onset compared to oral administration 3.
- Consider alternative routes (oral, sublingual, or intravenous) unless IM administration is specifically required 3.
Standard Needle Specifications for Deltoid IM Injection
Needle Length
- 1-1.5 inches is standard for deltoid injections in average-weight adults
- Adjust based on patient body habitus (shorter needles for smaller patients, longer for larger patients)
Needle Gauge
- 22-25 gauge is appropriate for intramuscular injections
- Smaller gauge (higher number) may reduce injection site pain but increases injection time
Dosing Context
Dose Appropriateness
- The 0.25mg dose is substantially lower than standard therapeutic doses used in clinical practice 4.
- For acute agitation in adolescents/adults, typical IM doses range from 2-4mg 4.
- For status epilepticus, the recommended dose is 0.1 mg/kg (maximum 4mg per dose) 4.
- Underdosing lorazepam has been associated with treatment failure and progression to refractory status epilepticus 5.
Clinical Monitoring Required
- Monitor oxygen saturation and respiratory effort during and after administration, as lorazepam can cause respiratory depression, especially when combined with other sedatives or opioids 4, 6.
- Be prepared to support ventilation if needed 6.
- The risk of apnea is increased with rapid administration or concomitant use of other CNS depressants 4, 6.