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# Ceftriaxone
## Overview
Ceftriaxone is a third-generation cephalosporin antibiotic that inhibits bacterial cell wall synthesis. It is characterized by a long half-life, allowing for once-daily dosing, and biliary excretion, which eliminates the need for renal dose adjustment in most patients.
## Primary Indications
* Community-acquired pneumonia (CAP)
* Meningitis (high-dose)
* Complicated intra-abdominal infections (often in combination with metronidazole)
* Gonorrhea (uncomplicated)
* Pyelonephritis and urinary tract infections
* Skin and soft tissue infections
* Lyme disease (neurologic/cardiac)
## Adult Dosing
* **Standard infections:** 1–2 g IV/IM every 24 hours.
* **Meningitis:** 2 g IV every 12 hours.
* **Uncomplicated Gonorrhea:** 500 mg IM as a single dose (patients <150 kg); 1 g IM for patients ≥150 kg.
* **Maximum clinical dose:** Generally 4 g/day for severe infections.
## Pediatric Dosing
* **Standard infections:** 50–75 mg/kg IV/IM once daily. Maximum 2 g/day.
* **Meningitis:** 100 mg/kg/day (divided every 12 or 24 hours). Maximum 4 g/day.
* **Neonates (Postnatal age 0-28 days):** 50 mg/kg/day once daily. Maximum 50 mg/kg/day.
## Dose Adjustments
* **Renal Impairment:** No dosage adjustment necessary in patients with renal impairment, provided hepatic function is normal.
* **Hepatic Impairment:** No adjustment required unless severe hepatic dysfunction is present; in cases of combined severe hepatic and renal impairment, monitor serum concentrations carefully.
## Contraindications
* Hypersensitivity to ceftriaxone, cephalosporins, or any component of the formulation.
* **Neonates (≤28 days):** Contraindicated if the neonate requires (or is expected to require) calcium-containing IV solutions (including TPN) due to the risk of ceftriaxone-calcium precipitates in the lungs and kidneys.
## Adverse Effects
* **Common:** Injection site reactions (IV/IM), diarrhea, rash.
* **Serious:** Biliary sludge/pseudolithiasis, *Clostridioides difficile*-associated diarrhea, hemolytic anemia, and anaphylaxis.
## Key Drug Interactions
* **Calcium-containing IV solutions:** Risk of life-threatening precipitates; must avoid co-administration in neonates (≤28 days). Do not mix or run in the same Y-site in any age group if possible.
* **Oral Contraceptives:** Potential for reduced efficacy (though evidence is inconsistent).
* **Anticoagulants:** May enhance the effects of Vitamin K antagonists (e.g., warfarin) by affecting gut flora and Vitamin K synthesis.
## Monitoring
* **Baseline:** Renal and hepatic function assessment.
* **During Therapy:** Monitor for signs of *C. difficile* (diarrhea), biliary symptoms (abdominal pain/ultrasound if prolonged), and hematologic parameters during long-term therapy.
## Clinical Pearls
* Ceftriaxone is 95-98% protein-bound; this allows for high efficacy but can displace bilirubin, exacerbating hyperbilirubinemia in neonates (hence the contraindication).
* When administering IM, use 1% lidocaine as a diluent if allowed by institutional policy to reduce significant injection pain.
* It does **not** provide activity against *Enterococcus* species, methicillin-resistant *Staphylococcus aureus* (MRSA), or *Pseudomonas aeruginosa*.
* *Note: Dosing can vary significantly based on local institutional antimicrobial stewardship protocols.*
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**Disclaimer:** This information is for educational purposes only. Always verify doses, contraindications, and compatibility with your institution's clinical guidelines and the most current manufacturer prescribing information prior to administration.
