Adults

1-2 gm once daily by IV or IM administration. In severe infections, the dose may be increased to 4 gm once daily.

Elderly

No dosage adjustment is generally required unless there is severe renal or hepatic impairment.

Renal_impairment

No dosage adjustment required for mild to moderate renal impairment. For severe renal impairment, dose should not exceed 2 gm daily without close monitoring.

Onset

Rapid onset (within 30 minutes for IV administration).

Excretion

Approximately 50-60% excreted unchanged in urine, and 40-50% excreted unchanged in bile/faeces.

Half life

Approximately 6 to 9 hours (prolonged in neonates).

Absorption

Rapid and complete absorption after intramuscular (IM) or intravenous (IV) administration.

Metabolism

Partially metabolized in the liver to inactive metabolites via hydrolysis; does not involve cytochrome P450 enzymes.

Probenecid

Does not significantly alter ceftriaxone pharmacokinetics, unlike some other cephalosporins.

Aminoglycosides

Potential for increased nephrotoxicity when co-administered, although some studies show synergistic effect against certain bacteria. Monitor renal function.

Oral anticoagulants

May enhance the anticoagulant effect of vitamin K antagonists (e.g., warfarin), increasing the risk of bleeding. Close monitoring of INR is advised.

Calcium-containing solutions

Concomitant use with intravenous calcium-containing solutions is contraindicated in neonates. In other age groups, a 48-hour washout period is recommended if calcium is administered intravenously.