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# Ceftriaxone
## Overview
Third-generation cephalosporin antibiotic with broad-spectrum bactericidal activity against Gram-positive and Gram-negative organisms. Long half-life allows once-daily dosing. Not active against MRSA, Enterococcus, or atypical pathogens.
## Primary Indications
- Community-acquired pneumonia
- Meningitis (including empiric coverage)
- Sepsis / bacteremia
- Urinary tract infections (complicated)
- Gonorrhea (uncomplicated, single dose)
- Lyme disease (neurologic or severe)
- Intra-abdominal infections (with metronidazole)
- Acute bacterial otitis media (single dose option)
## Adult Dosing
- **Community-acquired pneumonia / UTI / sepsis**: 1–2 g IV/IM every 24 hours
- **Meningitis**: 2 g IV every 12 hours
- **Gonorrhea (uncomplicated)**: 250 mg IM single dose (plus azithromycin or doxycycline per local protocol)
- **Lyme disease (neurologic)**: 2 g IV once daily for 14–28 days
- **Maximum daily dose**: 4 g in adults (some protocols allow up to 4 g for meningitis)
## Pediatric Dosing
- **Mild-moderate infection (e.g., pneumonia, UTI)**: 50–75 mg/kg IV/IM once daily (max 1 g/day)
- **Serious infection (e.g., meningitis, sepsis)**: 100 mg/kg IV/IM once daily (max 4 g/day) or divided every 12 hours for meningitis
- **Gonorrhea**: 125 mg IM single dose (children >45 kg: use adult dose)
- **Acute otitis media**: 50 mg/kg IM single dose (max 1 g)
- **Neonates (≤28 days)**: 50 mg/kg IV once daily. Use caution; avoid in hyperbilirubinemic neonates (risk of bilirubin displacement).
## Dose Adjustments
- **Renal impairment**: No adjustment needed for CrCl >10 mL/min. For CrCl <10 mL/min, reduce to 1 g per day (or 50% of usual dose). Hemodialysis: no supplemental dose required.
- **Hepatic impairment**: No adjustment. Caution in combined severe hepatic and renal disease.
- **Elderly**: No adjustment unless renal function severely reduced.
## Contraindications
- Hypersensitivity to ceftriaxone, any cephalosporin, or severe penicillin allergy (cross-reactivity ~1–10%)
- **Neonates with hyperbilirubinemia** (especially premature) – risk of kernicterus due to bilirubin displacement
- **Do not co-administer calcium-containing IV solutions** in neonates ≤28 days – risk of fatal ceftriaxone-calcium precipitates. In patients >28 days, avoid simultaneous administration; separate by at least 48 hours after last ceftriaxone dose.
## Adverse Effects
- **Common**: Diarrhea, nausea, rash, injection site pain (IM)
- **Serious**:
- *C. difficile* diarrhea
- Anaphylaxis
- Hemolytic anemia (rare, immune-mediated)
- Biliary pseudolithiasis (reversible, especially with high doses)
- Neutropenia, thrombocytopenia (prolonged use)
- Drug-induced liver injury (rare)
## Key Drug Interactions
- **Calcium-containing IV solutions**: Do not administer within 48 hours of ceftriaxone in neonates; use separate lines in older patients.
- **Warfarin**: May potentiate INR – monitor.
- **Aminoglycosides**: Synergistic but monitor renal function.
- **Live vaccines (e.g., typhoid)**: May reduce effectiveness – avoid concurrent use.
## Monitoring
- Renal function (baseline and periodic)
- CBC with differential (especially prolonged therapy)
- Signs of C. difficile (diarrhea >3 days after starting)
- INR if on warfarin
- Calcium precipitation risk in neonates (observe for respiratory distress, seizures)
## Clinical Pearls
- **Do not administer IV ceftriaxone with calcium-containing fluids** (e.g., Ringer’s lactate) in any line – use separate lines or flush thoroughly.
- **Intramuscular injection**: Reconstitute with 1% lidocaine (without epinephrine) to reduce pain – 250 mg or 350 mg vial: 0.9 mL lidocaine; 1 g vial: 3.6 mL lidocaine.
- **Biliary pseudolithiasis** (sludge/gallstones) is dose-dependent and reversible; do not mistake for cholecystitis.
- **Ceftriaxone has no activity against MRSA, Enterococcus, or Pseudomonas aeruginosa** – not appropriate for empiric coverage of these pathogens.
- **Half-life ~8 hours** – allows once-daily dosing for most infections; twice-daily for meningitis.
*This information is for educational purposes only. Always verify current prescribing information from local drug references, guidelines, and the patient's specific clinical context.*
