Ceftriaxone
**Ceftriaxone** is a potent, injectable **third-generation cephalosporin** antibiotic. - **Broad Spectrum**: It retains the gram-positive activity of first- and second-generation agents but features significantly expanded gram-negative coverage (e.g., *Enterobacteriaceae*). - **Clinical Utility**: Often reserved for serious infections where less expensive agents are ineffective, or to avoid the nephrotoxicity associated with aminoglycosides. - **Key Advantages**: Exhibits excellent penetration into the central nervous system (CNS), making it highly effective for meningitis. Its long half-life and activity against *Borrelia burgdorferi* also make it a viable option for treating Lyme disease.
Mechanism: Like all beta-lactam antibiotics, ceftriaxone is **bactericidal**. - **Mechanism**: It binds to specific **penicillin-binding proteins (PBPs)** located inside the bacterial cell wall. - **Pathway**: Binding to PBPs → Inhibition of the third and final stage of bacterial cell wall synthesis → Disruption of peptidoglycan cross-linking → Autolysin-mediated **bacterial cell lysis** and death.
Dosing by species
- Systemic infections · 25-50 mg/kg IV , IM or Intraosseous q12h as long as necessary · IV/IM/Intraosseous · q12h · As long as necessary
- Susceptible infections · 25-50 mg/kg q12h IV or IM · IV/IM · q12h · Excellent CSF and bone penetration; expensive.
- Susceptible infections · 20 mg/kg IV q12h · IV · q12h
- Meningitis/borreliosis · 15-50 mg/kg (maximum single dose in humans is 1 gram) IV or IM q12h for 4-14 days · IV/IM · q12h · 4-14 days
- Preoperative/intraoperative use · 25 mg/kg (maximum single dose in humans is 1 gram) IM or IV one time · IM/IV · once · 1 dose
- Skin, genitourinary infections · 25 mg/kg IM once daily (q24h) for 7-14 days · IM · q24h · 7-14 days
- Infectious endocarditis and documented resistance against or other contraindications for fluoroquinolones and aminoglycosides · 20 mg/kg IV q12h · IV · q12h
- General susceptible infections · 15-50 mg/kg (route not specified) once daily · Not specified · q24h
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Prior allergic reaction to cephalosporins
Adverse effects
- Pain on IM injection
- Hypersensitivity reactions (rash)
- Granulocytopenia / thrombocytopenia
- Diarrhea
- Mild azotemia
- Biliary sludging (at very high doses)
- Increased liver enzymes, BUN, and creatinine
Drug interactions
- Aminoglycosides / Nephrotoxic drugs · Potential additive nephrotoxicity; in vitro studies show synergistic or additive antibacterial activity.
- Calcium · Concomitant use with calcium-containing solutions has caused fatal calcium-ceftriaxone precipitates in neonates. Do not mix with calcium or administer within 48 hours of ceftriaxone.
Monitoring
- Clinical efficacy
- CBC (with long-term therapy)
- Renal function (BUN, Serum Creatinine, urinalysis)
- Liver enzymes (AST, ALT)
Overdose
Limited information is available regarding acute toxicity. Overdoses should be monitored and treated symptomatically and supportively if required.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.