Ceftriaxone inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins and disrupting peptidoglycan cross-linking. As a third-generation cephalosporin, it provides extended gram-negative coverage compared to first-generation agents like cefadroxil and cephalexin, while retaining gram-positive activity. The drug crosses the blood-brain barrier well, which is clinically relevant for casualties with penetrating head wounds or suspected CNS involvement.

• Open combat wound infection prophylaxis when casualty cannot tolerate oral medications (TCCC 2026)
• Penetrating trauma with anticipated delayed evacuation
• Casualty with altered mental status precluding oral antibiotic administration
• Suspected intra-abdominal or genitourinary penetrating injury
• Severe community-acquired pneumonia, meningitis (hospital indications)

• Known severe cephalosporin or penicillin allergy with prior anaphylaxis
• Neonates with hyperbilirubinemia (calcium-ceftriaxone precipitation risk)
• Concurrent IV calcium-containing solutions in neonates

Common side effects include injection site reactions, gastrointestinal upset, and rash. Cross-reactivity with penicillin allergy is approximately 1 to 10 percent. Ceftriaxone can precipitate with calcium-containing IV solutions; do not administer through the same IV line as calcium gluconate or chloride without flushing thoroughly. Biliary sludging can occur with prolonged use. Monitor for signs of allergic reaction. IM administration is painful; reconstitute with lidocaine if available and protocol permits.

Pediatric dosing is not addressed in primary TCCC doctrine. Standard civilian pediatric dosing is 50 to 100 mg/kg IV/IM once daily, not to exceed 2 grams. Avoid in neonates. Consult medical control and local standing orders before administration.

Peak Effect: IV: end of infusion. IM: 1.5 to 2 hours after injection.

Duration: 24 hours (supports once-daily dosing due to long half-life)

Store powder vials at controlled room temperature (15 to 30 degrees Celsius). Protect from light. Reconstituted solution is stable for 24 hours at room temperature or 10 days refrigerated, but should be used promptly in tactical settings.

Reconstitution:

Ceftriaxone is supplied as a sterile powder. Reconstitute with sterile water for injection, normal saline, or 1 percent lidocaine (IM use, if protocol permits). For 1 gram vial, add 9.6 mL diluent for a final concentration of 100 mg/mL. For 2 gram vial, use proportionally more diluent. Swirl gently to dissolve; do not shake vigorously.

Ceftriaxone is the parenteral alternative in the 2026 TCCC wound infection prophylaxis algorithm. It is selected when the casualty cannot tolerate oral medications, which includes altered mental status, severe nausea or vomiting, abdominal trauma, and shock. The once-daily dosing schedule is a significant operational advantage over multi-dose regimens in prolonged field care environments. The drug's CNS penetration also makes it appropriate for casualties with penetrating head wounds where CNS infection is a consideration.