Pharmacokinetic profile of ceftriaxone in man.

In human subjects, ceftriaxone exhibits an exceptionally long elimination half-life (5.8 to 8.7 hours) and a small degree of nonlinearity in its pharmacokinetics which can be ignored in its clinical applications. Thirty-three to 67 percent of a dose is excreted in the urine as unchanged drug, and the remainder is secreted in the bile and ultimately is found in the feces as microbiologically inactive compounds. Ceftriaxone is rapidly and completely absorbed following intramuscular administration. Multiple dosing of ceftriaxone with doses ranging from 0.5 to 2 g at 12- or 24-hour intervals by intravenous and intramuscular routes resulted in 15 to 36 percent accumulation of ceftriaxone in plasma and no change in its elimination half-life. The volume of distribution and the plasma clearance of ceftriaxone in pediatric patients were threefold greater than those in adults, and ceftriaxone penetrated the inflamed meninges of infants and children with bacterial meningitis. Small changes in the pharmacokinetics of ceftriaxone in elderly subjects or patients with renal or hepatic dysfunction are such that dose adjustments should not be necessary with a ceftriaxone dosage up to 2 g per day. Ceftriaxone was not removed to any significant extent from plasma by hemodialysis. In a small percentage of patients, on dialysis, the elimination rate of ceftriaxone was significantly reduced, suggesting that plasma concentrations of ceftriaxone should be monitored in these patients to determine if dosage adjustments are necessary.