Trick of the Trade
Ceftriaxone for IM use can be diluted with lidocaine 1% :
- Ceftriaxone 250 mg vial – mix with 0.9 mL of lidocaine 1% = 250 mg/mL
- Ceftriaxone 1000 mg vial – mix with 2.1 mL of lidocaine 1% = 350 mg/mL
What do the patients say?
In a double-blind crossover study , patients receiving IM ceftriaxone diluted with lidocaine 1% experienced 50% less pain compared to using sterile water for injection as a diluent. Using a 100 mm visual analog scale shortly after the shot, patients rated lidocaine-ceftriaxone pain as 25 mm compared to 50 mm for water-ceftriaxone. There was significant pain relief sustained up to 1 hour later.
How to Order
Depending on your institution, you may need to write two orders, i.e.,:
- Ceftriaxone 250 mg IM x 1
- Lidocaine 1% 0.9 mL, please use for ceftriaxone reconstitution (If a route for lidocaine is required, use “other” or “IM”)
Or just write,
- Ceftriaxone 250 mg IM x 1, mixed with lidocaine 1%
Please check with your local pharmacist to see what is preferred in your emergency department.
And a reminder, if you have a functioning IV line, 250 mg of ceftriaxone for sexually transmitted infections can be administered IV instead of IM as previously posted on ALiEM.
- Lexi-Comp Online (TM), Pediatric & Neonatal Lexi-Drugs Online (TM), Hudson, Ohio: Lexi-Comp, Inc.; January 29, 2011
- Antimicrob Agents Chemother. 1996 February; 40(2): 485–487. PMID: 8834905
Image courtesy of Renjith Krishnan