What is the recommended dosage of Ceftriaxone (a cephalosporin antibiotic) for treating infections in adults?

Ceftriaxone Dosing in Adults

For most adult infections, administer ceftriaxone 1-2 grams IV or IM once daily, with the maximum total daily dose not exceeding 4 grams. 1

Standard Dosing by Infection Type

General Infections

• Standard dose: 1-2 grams IV/IM once daily (or divided twice daily) depending on infection type and severity 1
• Maximum daily dose: 4 grams total 1
• Duration: Continue for at least 2 days after signs and symptoms resolve; typical duration is 4-14 days 1
• Administration: IV infusion over 30 minutes 1

Central Nervous System Infections

For bacterial meningitis, use 2 grams IV every 12 hours (total 4 grams daily) 2

Pathogen-specific meningitis dosing:

• Pneumococcal meningitis: 2 grams IV every 12 hours for 10-14 days (extend if slow response) 2
• Meningococcal meningitis: 2 grams IV every 12 hours for 5 days 2
• Haemophilus influenzae meningitis: 2 grams IV every 12 hours for 10 days 2
• Enterobacteriaceae CNS infections: 2 grams IV every 12 hours for 21 days 2

For penicillin-resistant pneumococci, add vancomycin 15-20 mg/kg IV twice daily or rifampicin 600 mg twice daily to the ceftriaxone regimen 2

Gonococcal Infections

• Uncomplicated gonorrhea: 250 mg IM as single dose 1
• Disseminated gonococcal infection (DGI): 1 gram IM or IV every 24 hours, continue for 24-48 hours after improvement begins, then switch to oral therapy to complete one week 2
• Gonococcal meningitis: 1-2 grams IV every 12 hours for 10-14 days 2
• Gonococcal endocarditis: 1-2 grams IV every 12 hours for at least 4 weeks 2
• Gonococcal conjunctivitis: 1 gram IM as single dose 2

Endocarditis

For highly penicillin-susceptible viridans group streptococci and S. gallolyticus (MIC ≤0.12 μg/mL):

• Monotherapy: 2 grams IV/IM once daily for 4 weeks 3
• Combination therapy (2-week regimen): 2 grams IV/IM once daily for 2 weeks plus gentamicin 3 mg/kg daily for 2 weeks 3
  • The 2-week regimen is not intended for patients with cardiac/extracardiac abscess, creatinine clearance <20 mL/min, or eighth cranial nerve dysfunction 3

For HACEK microorganism endocarditis: 2 grams IV/IM once daily for 4 weeks (6 weeks for prosthetic valve) 2

Other Specific Infections

• Surgical prophylaxis: 1 gram IV as single dose 30 minutes to 2 hours before surgery 1
• Neurosyphilis (penicillin-allergic patients): 2 grams IM or IV daily for 10-14 days 2
• Streptococcus pyogenes infections: Continue therapy for at least 10 days 1

Special Populations and Considerations

Renal and Hepatic Impairment

• No dosage adjustment necessary for renal or hepatic impairment alone 1
• For elderly patients without severe renal/hepatic impairment, no modification needed up to 2 grams per day 1

Outpatient Parenteral Antibiotic Therapy (OPAT)

For appropriate candidates (afebrile, clinically improving, received ≥5 days inpatient therapy, reliable IV access, 24-hour access to medical care):

• Initial: 2 grams IV twice daily 2
• After first 24 hours: May use 4 grams IV once daily 2

Resistant Organisms

For infections with elevated minimum inhibitory concentrations (MICs) or ceftriaxone-resistant strains:

• Higher doses required: Consider 2 grams IV every 12 hours (twice-daily dosing) 2
• Treatment failures have been reported with lower doses (250-500 mg), particularly for pharyngeal infections with elevated MICs 2

Critical Safety Warnings

Calcium-Containing Solutions

Never mix ceftriaxone with calcium-containing solutions (Ringer's solution, Hartmann's solution) due to precipitation risk 1

• In non-neonates, ceftriaxone and calcium-containing solutions may be given sequentially if infusion lines are thoroughly flushed between infusions 1

Drug Incompatibilities

Vancomycin, amsacrine, aminoglycosides, and fluconazole are incompatible with ceftriaxone in admixtures 1

Common Adverse Effects

• Rash, fever, diarrhea, neutropenia 3
• Liver function abnormalities and gallbladder "sludging" with ceftriaxone use 3

Dosing Algorithm

1. Identify infection site and severity:

   • CNS involvement → 2 grams IV every 12 hours
   • Endocarditis → 2 grams IV/IM once daily for 4 weeks
   • Uncomplicated gonorrhea → 250 mg IM single dose
   • Other serious infections → 1-2 grams IV/IM once daily

2. Consider pathogen susceptibility:

   • Resistant organisms or elevated MICs → Increase to twice-daily dosing
   • Penicillin-resistant pneumococci → Add vancomycin or rifampicin

3. Adjust for special circumstances:

   • Elderly without severe organ dysfunction → No adjustment needed
   • OPAT candidates → May use once-daily high-dose after initial period

4. Monitor duration:

   • Continue at least 2 days after symptom resolution
   • Extend for complicated infections or slow response