Monocef (Ceftriaxone) Injection Dilution Guidelines
Intravenous Administration
For IV infusion, reconstitute ceftriaxone powder by adding the specified volume of diluent to achieve approximately 100 mg/mL concentration, then further dilute to a final concentration between 10-40 mg/mL for administration over 30 minutes (60 minutes in neonates). 1
Reconstitution Volumes for IV Use
The FDA-approved reconstitution protocol requires specific diluent volumes to achieve the initial 100 mg/mL concentration 1:
- 250 mg vial: Add 2.4 mL of diluent
- 500 mg vial: Add 4.8 mL of diluent
- 1 gram vial: Add 9.6 mL of diluent
- 2 gram vial: Add 19.2 mL of diluent
After reconstitution at these volumes, withdraw the entire contents and further dilute with compatible IV solution to achieve the desired final concentration of 10-40 mg/mL 1. Lower concentrations may be used if clinically indicated 1.
Administration Parameters
- Infusion duration: 30 minutes for all patients except neonates 1
- Neonatal infusion: Must be administered over 60 minutes to reduce risk of bilirubin encephalopathy 1
- Recommended concentration range: 10-40 mg/mL for final infusion 1
Intramuscular Administration
For IM injection, reconstitute to achieve either 250 mg/mL or 350 mg/mL concentration depending on the vial size and clinical need. 1
Reconstitution Volumes for IM Use
The FDA provides two concentration options 1:
For 250 mg/mL concentration:
- 250 mg vial: Add 0.9 mL of diluent
- 500 mg vial: Add 1.8 mL of diluent
- 1 gram vial: Add 3.6 mL of diluent
- 2 gram vial: Add 7.2 mL of diluent
For 350 mg/mL concentration:
- 500 mg vial: Add 1 mL of diluent
- 1 gram vial: Add 2.1 mL of diluent
- 2 gram vial: Add 4.2 mL of diluent
Critical IM Administration Considerations
- The 350 mg/mL concentration is not recommended for the 250 mg vial as complete withdrawal may not be possible 1
- Inject deeply into a large muscle mass with aspiration to avoid intravascular injection 1
- IM injections are painful and patients should be counseled accordingly 2
Compatible Diluents
Never use calcium-containing solutions such as Ringer's solution or Hartmann's solution, as particulate formation will occur. 1
Acceptable IV Diluents
- 0.9% Sodium Chloride Injection
- 5% Dextrose in Water (D5W)
- Sterile Water for Injection 1
Drug Compatibility Warnings
- Metronidazole: Compatible at concentrations not exceeding 5-7.5 mg/mL metronidazole with ceftriaxone 10 mg/mL, stable for 24 hours at room temperature only in 0.9% saline or D5W (do not refrigerate) 1
- Incompatible drugs: Vancomycin, amsacrine, aminoglycosides, and fluconazole must not be mixed with ceftriaxone 1
- When administering incompatible drugs sequentially, thoroughly flush IV lines with compatible fluid between administrations 1
Storage After Reconstitution
- Store unreconstituted powder at 20-25°C (68-77°F) protected from light 1
- Specific stability data for reconstituted solutions varies by diluent and concentration—consult package insert for detailed stability information 1
Special Population Considerations
Neonatal Precautions
- Contraindicated in premature neonates 1
- Contraindicated in neonates ≤28 days requiring calcium-containing IV solutions due to fatal precipitation risk 1
- Contraindicated in hyperbilirubinemic neonates 1
- Must use 60-minute infusion time (not 30 minutes) 1
Pediatric Dosing Context
While not strictly about dilution, understanding typical pediatric doses helps determine appropriate dilution volumes 2:
- Meningitis: 100 mg/kg/day (maximum 4 grams daily) 2
- Severe infections: 50-100 mg/kg/day 2
- Less severe infections: 50-75 mg/kg/day 2
Adult Dosing Context
Standard adult doses range from 1-2 grams once or twice daily, with maximum 4 grams daily 3, which informs the volume of final dilution needed for safe administration.