Pharmacokinetic parameters for cefepime in healthy adult male volunteers (n=9) following single 30‑minute infusions (IV) of cefepime 500 mg, 1 g, and 2 g are summarized in Table 7. Elimination of cefepime is principally via renal excretion with an average (±SD) half-life of 2 (±0.3) hours and total body clearance of 120 (±8) mL/min in healthy volunteers. Cefepime pharmacokinetics are linear over the range 250 mg to 2 g. There is no evidence of accumulation in healthy adult male volunteers (n=7) receiving clinically relevant doses for a period of 9 days.
Table 7: Mean Pharmacokinetic Parameters for Cefepime (±SD), Intravenous Administration
Cefepime for Injection
|
Parameter
| 500 mg IV
| 1 g IV
| 2 g IV
|
Cmax, mcg/mL
| 39.1 (3.5)
| 81.7 (5.1)
| 163.9 (25.3)
|
AUC, h•mcg/mL
| 70.8 (6.7)
| 148.5 (15.1)
| 248.8 (30.6)
|
Number of subjects (male)
| 9
| 9
| 9
|
Pharmacokinetic parameters for cefepime following a single intramuscular injection are summarized in Table 8. The pharmacokinetics of cefepime are linear over the range of 500 mg to 2 g intramuscularly and do not vary with respect to treatment duration.
Table 8: Mean Pharmacokinetic Parameters for Cefepime (±SD), Intramuscular Administration
Cefepime for Injection |
Parameter
| 500 mg IM
| 1 g IM
| 2 g IM
|
Cmax, mcg/mL
| 13.9 (3.4)
| 29.6 (4.4)
| 57.5 (9.5)
|
Tmax, h
| 1.4 (0.9)
| 1.6 (0.4)
| 1.5 (0.4)
|
AUC, h•mcg/mL
| 60 (8)
| 137 (11)
| 262 (23)
|
Number of subjects (male)
| 6
| 6
| 12
|
Absorption
Following intramuscular (IM) administration, cefepime is completely absorbed.
Distribution
The average steady-state volume of distribution of cefepime is 18 (±2) L. The serum protein binding of cefepime is approximately 20% and is independent of its concentration in serum.
Cefepime is excreted in human milk at a concentration of 0.5 mcg/mL. A nursing infant consuming approximately 1,000 mL of human milk per day would receive approximately 0.5 mg of cefepime per day [see Use in Specific Populations (8.3)].
Concentrations of cefepime achieved in specific tissues and body fluids are listed in Table 9.
Table 9: Mean Concentrations of Cefepime in Specific Body Fluids (mcg/mL) or Tissues (mcg/g)
Tissue or Fluid
| Dose/ Route | # of Patients
| Mean Time of Sample Post-dose (h)
| Mean Concentration
|
Blister Fluid
| 2 g IV
| 6
| 1.5
| 81.4 mcg/mL
|
Bronchial Mucosa
| 2 g IV
| 20
| 4.8
| 24.1 mcg/g
|
Sputum
| 2 g IV
| 5
| 4
| 7.4 mcg/mL
|
Urine
| 500 mg IV 1 g IV 2 g IV
| 8 12 12
| 0 to 4 0 to 4 0 to 4
| 292 mcg/mL 926 mcg/mL 3,120 mcg/mL
|
Bile
| 2 g IV
| 26
| 9.4
| 17.8 mcg/mL
|
Peritoneal Fluid
| 2 g IV
| 19
| 4.4
| 18.3 mcg/mL
|
Appendix
| 2 g IV
| 31
| 5.7
| 5.2 mcg/g
|
Gallbladder
| 2 g IV
| 38
| 8.9
| 11.9 mcg/g
|
Prostate
| 2 g IV
| 5
| 1
| 31.5 mcg/g
|
Data suggest that cefepime does cross the inflamed blood-brain barrier. The clinical relevance of these data is uncertain at this time.
Metabolism and Excretion
Cefepime is metabolized to N-methylpyrrolidine (NMP) which is rapidly converted to the N-oxide (NMP-N-oxide). Urinary recovery of unchanged cefepime accounts for approximately 85% of the administered dose. Less than 1% of the administered dose is recovered from urine as NMP, 6.8% as NMP-N-oxide, and 2.5% as an epimer of cefepime. Because renal excretion is a significant pathway of elimination, patients with renal dysfunction and patients undergoing hemodialysis require dosage adjustment [see Dosage and Administration (2.3)].
Specific Populations
Patients with Renal impairment
Cefepime pharmacokinetics have been investigated in patients with various degrees of renal impairment (n=30). The average half-life in patients requiring hemodialysis was 13.5 (±2.7) hours and in patients requiring continuous peritoneal dialysis was 19 (±2) hours. Cefepime total body clearance decreased proportionally with creatinine clearance in patients with abnormal renal function, which serves as the basis for dosage adjustment recommendations in this group of patients [see Dosage and Administration (2.3)].
Patients with Hepatic impairment
The pharmacokinetics of cefepime were unaltered in patients with hepatic impairment who received a single 1 g dose (n=11).
Geriatric patients
Cefepime pharmacokinetics have been investigated in elderly (65 years of age and older) men (n=12) and women (n=12) whose mean (SD) creatinine clearance was 74 (±15) mL/min. There appeared to be a decrease in cefepime total body clearance as a function of creatinine clearance. Therefore, dosage administration of cefepime in the elderly should be adjusted as appropriate if the patient’s creatinine clearance is 60 mL/min or less [see Dosage and Administration (2.3)].
Pediatric patients
Cefepime pharmacokinetics have been evaluated in pediatric patients from 2 months to 11 years of age following single and multiple doses on every 8 hours (n=29) and every 12 hours (n=13) schedules. Following a single intravenous dose, total body clearance and the steady-state volume of distribution averaged 3.3 (±1) mL/min/kg and 0.3 (±0.1) L/kg, respectively. The urinary recovery of unchanged cefepime was 60.4 (±30.4)% of the administered dose, and the average renal clearance was 2 (±1.1) mL/min/kg. There were no significant effects of age or gender (25 male vs. 17 female) on total body clearance or volume of distribution, corrected for body weight. No accumulation was seen when cefepime was given at 50 mg per kg every 12 hours (n=13), while Cmax, AUC, and t½ were increased about 15% at steady state after 50 mg per kg every 8 hours. The exposure to cefepime following a 50 mg per kg intravenous dose in a pediatric patient is comparable to that in an adult treated with a 2 g intravenous dose. The absolute bioavailability of cefepime after an intramuscular dose of 50 mg per kg was 82.3 (±15)% in eight patients.