Average plasma concentrations of ceftriaxone following a single 30-minute intravenous (IV) infusion of a 0.5, 1 or 2 g dose and intramuscular (IM) administration of a single 0.5 (250 mg/mL or 350 mg/mL concentrations) or 1 g dose in healthy subjects are presented in Table 1.
Table 1. Ceftriaxone Plasma Concentrations after Single Dose Administration Dose/Route | Average Plasma Concentrations (mcg/mL) |
0.5 hour | 1 hour | 2 hour | 4 hour | 6 hour | 8 hour | 12 hour | 16 hour | 24 hour |
0.5 g IV* | 82 | 59 | 48 | 37 | 29 | 23 | 15 | 10 | 5 |
0.5 g IM 250 mg/mL | 22 | 33 | 38 | 35 | 30 | 26 | 16 | ND | 5 |
0.5 g IM 350 mg/mL | 20 | 32 | 38 | 34 | 31 | 24 | 16 | ND | 5 |
1 g IV* | 151 | 111 | 88 | 67 | 53 | 43 | 28 | 18 | 9 |
1 g IM | 40 | 68 | 76 | 68 | 56 | 44 | 29 | ND | ND |
2 g IV* | 257 | 192 | 154 | 117 | 89 | 74 | 46 | 31 | 15 |
ND = Not determined. |
* IV doses were infused at a constant rate over 30 minutes.
Ceftriaxone was completely absorbed following IM administration with mean maximum plasma concentrations occurring between 2 and 3 hours post-dose. Multiple IV or IM doses ranging from 0.5 to 2 g at 12 to 24 hour intervals resulted in 15% to 36% accumulation of ceftriaxone above single dose values.
Ceftriaxone concentrations in urine are shown in Table 2.
Table 2. Urinary Concentrations of Ceftriaxone after Single Dose Administration Dose/Route | Average Urinary Concentrations (mcg/mL) |
0 to 2 hour | 2 to 4 hour | 4 to 8 hour | 8 to 12 hour | 12 to 24 hour | 24 to 48 hour |
0.5 g IV | 526 | 366 | 142 | 87 | 70 | 15 |
0.5 g IM | 115 | 425 | 308 | 127 | 96 | 28 |
1 g IV | 995 | 855 | 293 | 147 | 132 | 32 |
1 g IM | 504 | 628 | 418 | 237 | ND | ND |
2 g IV | 2692 | 1976 | 757 | 274 | 198 | 40 |
ND = Not determined. |
Thirty-three percent to 67% of a ceftriaxone dose was excreted in the urine as unchanged drug and the remainder was secreted in the bile and ultimately found in the feces as microbiologically inactive compounds. After a 1 g IV dose, average concentrations of ceftriaxone, determined from 1 to 3 hours after dosing, were 581 mcg/mL in the gallbladder bile, 788 mcg/mL in the common duct bile, 898 mcg/mL in the cystic duct bile, 78.2 mcg/g in the gallbladder wall and 62.1 mcg/mL in the concurrent plasma.
Over a 0.15 to 3 g dose range in healthy adult subjects, the values of elimination half-life ranged from 5.8 to 8.7 hours; apparent volume of distribution from 5.78 to 13.5 L; plasma clearance from 0.58 to 1.45 L/hour; and renal clearance from 0.32 to 0.73 L/hour. Ceftriaxone is reversibly bound to human plasma proteins, and the binding decreased from a value of 95% bound at plasma concentrations of <25 mcg/mL to a value of 85% bound at 300 mcg/mL. Ceftriaxone crosses the blood placenta barrier.
The average values of maximum plasma concentration, elimination half-life, plasma clearance and volume of distribution after a 50 mg/kg IV dose and after a 75 mg/kg IV dose in pediatric patients suffering from bacterial meningitis are shown in Table 3. Ceftriaxone penetrated the inflamed meninges of infants and pediatric patients; CSF concentrations after a 50 mg/kg IV dose and after a 75 mg/kg IV dose are also shown in Table 3.
Table 3. Average Pharmacokinetic Parameters of Ceftriaxone in Pediatric Patients with Meningitis | 50 mg/kg IV | 75 mg/kg IV |
Maximum Plasma Concentrations (mcg/mL) | 216 | 275 |
Elimination Half-life (hour) | 4.6 | 4.3 |
Plasma Clearance (mL/hour/kg) | 49 | 60 |
Volume of Distribution (mL/kg) | 338 | 373 |
CSF Concentration – inflamed meninges (mcg/mL) | 5.6 | 6.4 |
Range (mcg/mL) | 1.3 to 18.5 | 1.3 to 44 |
Time after dose (hour) | 3.7 (± 1.6) | 3.3 (± 1.4) |
Compared to that in healthy adult subjects, the pharmacokinetics of ceftriaxone were only minimally altered in elderly subjects and in patients with renal impairment or hepatic dysfunction (Table 4); therefore, dosage adjustments are not necessary for these patients with ceftriaxone dosages up to 2 g per day. Ceftriaxone was not removed to any significant extent from the plasma by hemodialysis; in six of 26 dialysis patients, the elimination rate of ceftriaxone was markedly reduced.
Table 4. Average Pharmacokinetic Parameters of Ceftriaxone in Humans Subject Group | Elimination Half-Life (hour) | Plasma Clearance (L/hour) | Volume of Distribution (L) |
Healthy Subjects | 5.8 to 8.7 | 0.58 to 1.45 | 5.8 to 13.5 |
Elderly Subjects (mean age, 70.5 year) | 8.9 | 0.83 | 10.7 |
Patients With Renal Impairment | | | |
Hemodialysis Patients (0 to 5 mL/min)* | 14.7 | 0.65 | 13.7 |
Severe (5 to 15 mL/min) | 15.7 | 0.56 | 12.5 |
Moderate (16 to 30 mL/min) | 11.4 | 0.72 | 11.8 |
Mild (31 to 60 mL/min) | 12.4 | 0.70 | 13.3 |
Patients With Liver Disease | 8.8 | 1.1 | 13.6 |
* Creatinine clearance.
The elimination of ceftriaxone is not altered when ceftriaxone is co-administered with probenecid.