Plasma concentrations
The mean pharmacokinetic parameters of ceftobiprole in healthy adults for a single 500 mg dose administered as a 2-hour infusion and multiple 500 mg doses administered every 8 hours as 2-hour infusions (see section 4.2) are summarised in Table 4. Pharmacokinetic characteristics were similar with single and multiple dose administration.
Table 4 Mean (standard deviation) pharmacokinetic parameters of ceftobiprole in healthy adults
| Parameter | Single 500 mg dose administered as a 120-minute infusion | Multiple 500 mg doses administered every 8 hours as 120 minute infusions |
| Cmax (μg/mL) | 29.2 (5.52) | 33.0 (4.83) |
| AUC a (μg• h/mL) | 90.0 (12.4) | 102 (11.9) |
| t 1/2 (hours) | 3.1 (0.3) | 3.3 (0.3) |
| CL (L/h) | 4.89 (0.69) | 4.98 (0.58) |
a AUC is given as AUClast and AUC0-8h for single dose and multiple dose, respectively.
Rich and/or sparse plasma samples were collected in all Phase 3 studies. Based on the rich plasma concentration-time profiles in patients with HAP and CAP, the PK properties of ceftobiprole in these populations was similar to that observed in healthy subjects.
PK/PD studies in the neutropenic mouse thigh infection model indicated that unbound, %fT>MIC was the PK/PD index and a target of approximately 30% and 60% would provide efficacious dosing for ceftobiprole for treatment of infections caused by Gram-positive and Gram-negative pathogens, respectively. Population PK analysis and PK/PD target attainment analysis were used to support the dosing regimen for ceftobiprole in adult and paediatric subjects.
Distribution
Ceftobiprole binds minimally (16%) to plasma proteins and binding is independent of concentration. Ceftobiprole steady-state volume of distribution (18 litres) approximates extracellular fluid volume in healthy adults.
Biodistribution
The active substance of Zevtera is ceftobiprole medocaril sodium, which is the prodrug of the active moiety ceftobiprole. Conversion from the prodrug ceftobiprole medocaril sodium, to the active moiety ceftobiprole, occurs rapidly and is mediated by non-specific plasma esterases. Prodrug concentrations are negligible and are measurable in plasma and urine only during infusion. The metabolite resulting from the cleavage of the prodrug is diacetyl which is an endogenous human compound.
Ceftobiprole undergoes minimal metabolism to the open-ring metabolite, which is microbiologically inactive. Systemic exposure of the open-ring metabolite was considerably lower than for ceftobiprole, accounting for approximately 4% of the parent exposure in subject with a normal renal function.
In vitro studies demonstrated that ceftobiprole is an inhibitor of the hepatocyte uptake transporters OATP1B1 and OATP1B3, but is not an inhibitor of PgP, BCRP, MDR1, MRP2, OAT1, OAT3, OCT1 or OCT2. Ceftobiprole is potentially a weak substrate of the renal tubule cells uptake transporters OAT1 and OCT2.
Ceftobiprole protein binding is low (16%) and is not a PgP inhibitor or substrate. The potential for other drugs to interact with ceftobiprole is minimal, since only a small fraction of ceftobiprole is metabolised. Therefore, no relevant drug‑drug interactions are anticipated (see section 4.5).
Since ceftobiprole does not undergo tubular secretion and only a fraction is reabsorbed, renal drug‑drug interactions are not expected.
Elimination
Ceftobiprole is eliminated primarily unchanged by renal excretion, with a half-life of approximately 3 hours. The predominant mechanism responsible for elimination is glomerular filtration, with some active reabsorption. Following single dose administration in healthy adults, approximately 89% of the administered dose is recovered in the urine as active ceftobiprole (83%), the open-ring metabolite (5%) and ceftobiprole medocaril (<1%).
Linearity/non-linearity
Ceftobiprole exhibits linear and time-independent pharmacokinetics. The Cmax and AUC of ceftobiprole increase in proportion to dose over a range of 125 mg to 1 g. Steady-state active substance concentrations are attained on the first day of dosing; no appreciable accumulation occurs with every-8-hour dosing in subjects with normal renal function.
Special populations
Renal impairment
The estimation of creatinine clearance should be based on the Cockcroft-Gault formula using actual body weight in adult patients and the Schwartz formula in paediatric patients. During treatment with ceftobiprole it is recommended that an enzymatic method of measuring serum creatinine be used (see section 4.4).
The pharmacokinetics of ceftobiprole are similar in healthy adults and subjects with mild renal impairment (CLCR 50 to 80 mL/min). Ceftobiprole AUC was 2.5- and 3.3-fold higher in subjects with moderate (CLCR 30 to < 50 mL/min) and severe (CLCR < 30 mL/min) renal impairment, respectively, than in healthy adults with normal renal function.
Dosage adjustment is recommended in patients with moderate to severe renal impairment (see section 4.2). Dose recommendations for paediatric patients are based on pharmacokinetic modelling.
AUCs of ceftobiprole and of the microbiologically inactive ring-opened metabolite are substantially increased in adult patients with end-stage renal disease who require haemodialysis compared with healthy adults. In a study where six adult subjects with end-stage renal disease on haemodialysis received a single dose of 250 mg ceftobiprole by intravenous infusion, ceftobiprole was demonstrated to be haemodialysable with an extraction ratio of 0.7 (see section 4.2).
There is insufficient information to recommend dosage adjustment in paediatric patients with CLCR < 10 mL/min/1.73 m2 or end-stage renal disease requiring dialysis.
Patients with creatinine clearance > 150mL/min
Ceftobiprole systemic clearance (CLSS) was 40% greater in adult subjects with a CLCR > 150 mL/min compared to subjects with a normal renal function (CLCR = 80-150 mL/min). Volume of distribution was 30% larger. In this population, based on pharmacokinetic/pharmacodynamic considerations, prolongation of duration of infusion is recommended (see section 4.2).
Hepatic impairment
The pharmacokinetics of ceftobiprole in patients with hepatic impairment have not been established. As ceftobiprole undergoes minimal hepatic metabolism and is predominantly excreted unchanged in the urine, the clearance of ceftobiprole is not expected to be affected by hepatic impairment (see section 4.2).
Elderly
Population pharmacokinetic data showed that age as an independent parameter has no effect on the pharmacokinetics of ceftobiprole. Dosage adjustment is not considered necessary in elderly patients with normal renal function (see section 4.2).
Paediatric population
Population pharmacokinetic data showed that glomerular filtration rate maturation has an effect on the pharmacokinetics of ceftobiprole in paediatric patients aged 1 year and younger. Weight-based dose adjustments are required for paediatric patients weighing less than 50 kg (see section 4.2).
The mean exposures to ceftobiprole in paediatric subjects with normal renal function based on population PK modelling are summarised in Table 5 for the proposed paediatric doses (see section 4.2) and are similar to the mean exposures observed in adults.
Table 5 Mean (standard deviation) pharmacokinetic parameters of ceftobiprole in paediatric subjects predicted from population PK modelling
| Age group | Dosing regimen | Cmax (µg/mL) | AUC0-24h (h.µg/mL) |
| Birth to <3 months | 15 mg/kg q12ha | 31.1 (7.05) | 298 (66.4) |
| 3 month to <2 years | 15 mg/kg q8h | 30.3 (5.32) | 278 (69.9) |
| 2 to <6 years | 15 mg/kg q8h | 30.8 (4.98) | 266 (55.3) |
| 6 to <12 years | 15 mg/kg q8h | 35.2 (5.94) | 312 (68.7) |
| 12 to <18 years | 10 mg/kg q8h | 26.6 (4.92) | 245 (56.9) |
| Adults | 500 mg q8h | 33.0 (4.83) | 306 (35.7) |
a - Patients with a body weight < 4 kg given 10 mg/kg q12h as a 2-h infusion.
Sex
Systemic exposure to ceftobiprole was higher in adult females than adult males (21% for Cmax and 15% for AUC), however the %T>MIC was similar in both males and females. Therefore, dosage adjustments based on gender are not considered necessary.
Race
Population pharmacokinetic analyses (including Caucasians, Black and Other groups) and a dedicated pharmacokinetic study in healthy Japanese adults showed no effect of race on the pharmacokinetics of ceftobiprole. Therefore, dosage adjustments based on race are not considered necessary.
Body weight
A study was performed in morbidly obese subjects. No dose adjustments based on body weight are required in adult populations but the dose should be adjusted by body weight in paediatric subjects weighing less than 50 kg.