Rocephin IM Reconstitution with Lidocaine
Reconstitute Rocephin (ceftriaxone) for intramuscular injection using 1% lidocaine solution without epinephrine, following the specific volume guidelines provided in the FDA labeling to achieve final concentrations of either 250 mg/mL or 350 mg/mL. 1
Standard Reconstitution Volumes
The FDA-approved reconstitution protocol specifies exact diluent volumes for each vial size 1:
For 250 mg/mL concentration:
- 500 mg vial: Add 1.8 mL of 1% lidocaine
- 1 g vial: Add 3.6 mL of 1% lidocaine
- 2 g vial: Add 7.2 mL of 1% lidocaine
For 350 mg/mL concentration:
- 500 mg vial: Add 1.0 mL of 1% lidocaine
- 1 g vial: Add 2.1 mL of 1% lidocaine
- 2 g vial: Add 4.2 mL of 1% lidocaine
Reconstitution Technique
Inject the lidocaine diluent into the vial and shake thoroughly until a complete solution forms. 1 Withdraw the entire contents of the vial into the syringe to equal the total labeled dose. 1
Critical Safety Requirements
Use only 1% lidocaine solution without epinephrine for IM reconstitution. 2, 1 The CDC specifically recommends plain 1% lidocaine and advises against using lidocaine with epinephrine. 2
Never use lidocaine-reconstituted ceftriaxone for intravenous administration—this preparation is strictly for intramuscular use only. 2 This is a critical safety distinction that must be observed.
Injection Technique
Inject the reconstituted solution deep into the body of a relatively large muscle, using aspiration to avoid unintentional intravascular injection. 1 This technique is standard for all intramuscular preparations. 1
Stability After Reconstitution
Ceftriaxone reconstituted with 1% lidocaine solution remains stable at the following timeframes 1:
- Room temperature (25°C): 24 hours for all concentrations (100,250, and 350 mg/mL)
- Refrigerated (4°C):
- 100 mg/mL: 10 days
- 250 mg/mL and 350 mg/mL: 3 days
Clinical Evidence Supporting Lidocaine Use
Lidocaine as a diluent significantly reduces injection pain without altering ceftriaxone pharmacokinetics or bioavailability. 3 A pharmacokinetic study demonstrated that 1% lidocaine does not affect elimination parameters, with mean peak plasma concentrations of 42 mcg/mL at 3 hours and elimination half-life of 7.0 hours, identical to water diluent. 3
The more concentrated 350 mg/mL solution is bioequivalent to the 250 mg/mL solution, with 90% confidence intervals for AUC and Cmax ratios falling within FDA bioequivalence range (0.80-1.25). 4 Both concentrations are well tolerated when reconstituted with lidocaine. 5, 4
Common Pitfalls to Avoid
- Do not use lidocaine with epinephrine for reconstitution 2
- Do not administer lidocaine-reconstituted ceftriaxone intravenously 2
- Do not use calcium-containing diluents (such as Ringer's solution or Hartmann's solution) as particulate formation can result 1
- Do not exceed the stability timeframes listed above; discard unused portions after the indicated periods 1