Clinical Pharmacology for Vabomere
Mechanism Of Action
VABOMERE is an antibacterial drug [see Microbiology].
Pharmacodynamics
Similar to other beta-lactam antibacterial drugs, the percentage of time of a dosing interval that unbound plasma concentration of meropenem exceeds the meropenem-vaborbactam minimum inhibitory concentration (MIC) against the infecting organism has been shown to best correlate with efficacy in animal and in vitro models of infection. The ratio of the 24-hour unbound plasma vaborbactam AUC to meropenem-vaborbactam MIC is the index that best predicts efficacy of vaborbactam in combination with meropenem in animal and in vitro models of infection.
Cardiac Electrophysiology
At a dose of 1 and 3 times the maximum approved recommended dose, Vabomere (meropenem and vaborbactam) does not prolong the QT interval to any clinically relevant extent.
Pharmacokinetics
Pharmacokinetic (PK) Parameters
The mean PK parameters of meropenem and vaborbactam in healthy adults with normal renal function after single and multiple 3-hour infusions of VABOMERE 4 grams (meropenem 2 grams and vaborbactam 2 grams) administered every 8 hours are summarized in Table 4.
The PK parameters of meropenem and vaborbactam were similar for single and multiple dose administration of VABOMERE.
Table 4: Pharmacokinetic Parameters (Mean [SD]) of Meropenem and Vaborbactam Following Administration of VABOMERE 4 grams (meropenem 2 grams and vaborbactam 2 grams) by 3-hour Infusion in Healthy Adult Subjects
| Parameter |
Meropenem |
Vaborbactam |
Single VABOMERE 4 grama Dose
(N=8) |
Multiple VABOMERE 4 grama Doses Administered Every 8 hours for 7 Days
(N=8) |
Single VABOMERE 4 grama Dose
(N=8) |
Multiple VABOMERE 4 grama Doses Administered Every 8 hours for 7 Days
(N=8) |
| Cmax (mg/L) |
46.0 (5.7) |
43.4 (8.8) |
50.7 (8.4) |
55.6 (11.0) |
| CL (L/h) |
14.6 (2.7) |
15.1 (2.8) |
12.3 (2.2) |
10.9 (1.8) |
| AUC (mg•h/L)b |
142.0 (28.0) |
138.0 (27.7) |
168.0 (32.2) |
196.0 (36.7) |
| T½ (h) |
1.50 (1.0) |
1.22 (0.3) |
1.99 (0.8) |
1.68 (0.4) |
Cmax = maximum observed concentration; CL = plasma clearance; AUC = area under the concentration time curve; T½ = half-life.
a Meropenem 2 grams and vaborbactam 2 grams administered as a 3-hour infusion
b AUC0-inf reported for single-dose administration; AUC0-8 reported for multiple-dose administration; AUC0 – 24 is 414 mg•h/L for meropenem and 588 mg•h/L for vaborbactam. |
The maximum plasma concentration (Cmax) and area under the plasma drug concentration time curve (AUC) of meropenem and vaborbactam proportionally increased with dose across the dose range studied (1 gram to 2 grams for meropenem and 0.25 grams to 2 grams for vaborbactam) when administered as a single 3-hour intravenous infusion. There is no accumulation of meropenem or vaborbactam following multiple intravenous infusions administered every 8 hours for 7 days in subjects with normal renal function.
The mean population PK parameters of meropenem and vaborbactam in 295 patients (including 35 patients with reduced renal function) after 3-hour infusions of VABOMERE 4 grams (meropenem 2 grams and vaborbactam 2 grams) administered every 8 hours (or dose adjusted based on renal function) are summarized in Table 5.
Table 5: Population Pharmacokinetic Parameters (Mean [SD]) of Meropenem and Vaborbactam Following Administration of VABOMERE 4 grams (meropenem 2 grams and vaborbactam 2 grams) by 3-hour Infusion in Patientsa
| Parameter |
Meropenem |
Vaborbactam |
| Cmax (mg/L) |
57.3 (23.0) |
71.3 (28.6) |
| AUC0-24, Day 1 (mg•h/L) |
637 (295) |
821 (369) |
| AUC0-24, steady-state (mg•h/L) |
650 (364) |
835 (508) |
| CL (L/h) |
10.5 (6.4) |
7.95 (4.3) |
| T½ (h) |
2.30 (2.5) |
2.25 (2.1) |
| a Meropenem 2 grams and vaborbactam 2 grams administered as a 3-hour infusion. |
Distribution
The plasma protein binding of meropenem is approximately 2%. The plasma protein binding of vaborbactam is approximately 33%.
The steady-state volumes of distribution of meropenem and vaborbactam in patients were 20.2 L and 18.6 L, respectively.
Elimination
The clearance of meropenem in healthy subjects following multiple doses is 15.1 L/h and for vaborbactam is 10.9 L/h. The t½ is 1.22 hours and 1.68 hours for meropenem and vaborbactam, respectively.
Metabolism
A minor pathway of meropenem elimination is hydrolysis of the beta-lactam ring (meropenem open lactam), which accounts for 22% of a dose eliminated via the urine.
Vaborbactam does not undergo metabolism.
Excretion
Both meropenem and vaborbactam are primarily excreted via the kidneys.
Approximately 40–60% of a meropenem dose is excreted unchanged within 24-48 hours with a further 22% recovered as the microbiologically inactive hydrolysis product. The mean renal clearance for meropenem was 7.8 L/h. The mean non-renal clearance for meropenem was 7.3 L/h which comprises both fecal elimination (~2% of dose) and degradation due to hydrolysis.
For vaborbactam, 75 to 95% of the dose was excreted unchanged in the urine over a 24 to 48 hour period. The mean renal clearance for vaborbactam was 8.9 L/h. The mean non-renal clearance for vaborbactam was 2.0 L/h indicating nearly complete elimination of vaborbactam by the renal route.
Specific Populations
Patients With Renal Impairment
Following a single dose of VABOMERE, pharmacokinetic studies with meropenem and vaborbactam in subjects with renal impairment have shown that meropenem AUC0-inf ratios to subjects with normal renal function are 1.28, 2.07, and 4.63 for subjects with mild (eGFR of 60 to 89 mL/min/1.73m²), moderate (eGFR of 30 to 59 mL/min/1.73m²), and severe (eGFR <30 mL/min/1.73m²) renal impairment, respectively; vaborbactam AUC0-inf ratios to subjects with normal renal function are 1.18, 2.31, and 7.8 for subjects with mild, moderate, and severe renal impairment, respectively [see DOSING AND ADMINISTRATION]. Hemodialysis removed 38% of the meropenem dose and 53% of the vaborbactam dose. Vaborbactam exposure was high in subjects with ESRD (eGFR <15 ml/min/1.73 m²). Vaborbactam exposure was higher when VABOMERE was administered after hemodialysis (AUC0-inf ratio to subjects with normal renal function of 37.5) than when VABOMERE was administered before hemodialysis (AUC0-inf ratio to subjects with normal renal function of 10.2) [see Use In Specific Populations  and DOSING AND ADMINISTRATION].
Patients With Hepatic Impairment
A pharmacokinetic study conducted with an intravenous formulation of meropenem in patients with hepatic impairment has shown no effects of liver disease on the pharmacokinetics of meropenem.
Vaborbactam does not undergo hepatic metabolism. Therefore, the systemic clearance of meropenem and vaborbactam is not expected to be affected by hepatic impairment.
Geriatric Patients
In elderly patients with renal impairment, plasma clearances of meropenem and vaborbactam were reduced, correlating with age-associated reduction in renal function [see DOSAGE AND ADMINISTRATION and Use In Specific Populations].
Male And Female Patients
Meropenem and vaborbactam Cmax and AUC were similar between males and females using a population pharmacokinetic analysis.
Racial Or Ethnic Groups
No significant difference in mean meropenem or vaborbactam clearance was observed across race groups using a population pharmacokinetic analysis.
Drug Interaction Studies
No drug-drug interaction was observed between meropenem and vaborbactam in clinical studies with healthy subjects.
No clinical studies have been conducted to evaluate the potential for VABOMERE to affect other drugs. Meropenem and vaborbactam do not inhibit the following cytochrome P450 isoforms in vitro at clinically relevant concentrations: CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 in human liver microsomes. In vitro data suggest a potential for weak induction of CYP1A2 (meropenem), CYP3A4 (meropenem and vaborbactam) and potentially other pregnane X receptor(PXR)-regulated enzymes and transporters [see DRUG INTERACTIONS].
In vitro data suggest a potential of meropenem and vaborbactam to inhibit OAT3 at the clinically relevant concentrations. Meropenem and vaborbactam do not inhibit the following hepatic and renal transporters in vitro at clinically relevant concentrations: P-gp, BCRP, OAT1, OCT1, OCT2, OATP1B1, OATP1B3 or BSEP. Meropenem and vaborbactam were not substrates of OAT1, OCT2, P-gp, BCRP, MATE1, and MATE2-K.
Meropenem and vaborbactam are substrates of OAT3 and as such, probenecid competes with meropenem for active tubular secretion and thus inhibits the renal excretion of meropenem and the same mechanism could apply for vaborbactam. Following administration of probenecid with meropenem, the mean systemic exposure increased 56% and the mean elimination half-life increased 38% [see DRUG INTERACTIONS].
Concomitant administration of meropenem and valproic acid has been associated with reductions in valproic acid concentrations with subsequent loss in seizure control [see DRUG INTERACTIONS ].
Microbiology
Mechanism Of Action
The meropenem component of VABOMERE is a penem antibacterial drug. The bactericidal action of meropenem results from the inhibition of cell wall synthesis. Meropenem penetrates the cell wall of most gram-positive and gram-negative bacteria to bind penicillin-binding protein (PBP) targets. Meropenem is stable to hydrolysis by most beta-lactamases, including penicillinases and cephalosporinases produced by gram-negative and gram-positive bacteria, with the exception of carbapenem hydrolyzing beta-lactamases.
The vaborbactam component of VABOMERE is a non-suicidal beta-lactamase inhibitor that protects meropenem from degradation by certain serine beta-lactamases such as Klebsiella pneumoniae carbapenemase (KPC). Vaborbactam does not have any antibacterial activity. Vaborbactam does not decrease the activity of meropenem against meropenem-susceptible organisms.
Resistance
Mechanisms of beta-lactam resistance may include the production of beta-lactamases, modification of PBPs by gene acquisition or target alteration, up-regulation of efflux pumps, and loss of outer membrane porin. VABOMERE may not have activity against gram-negative bacteria that have porin mutations combined with overexpression of efflux pumps.
Clinical isolates may produce multiple beta-lactamases, express varying levels of beta-lactamases, or have amino acid sequence variations, and other resistance mechanisms that have not been identified.
Culture and susceptibility information and local epidemiology should be considered in selecting or modifying antibacterial therapy.
VABOMERE demonstrated in vitro activity against Enterobacteriaceae in the presence of some beta-lactamases and extended-spectrum beta-lactamases (ESBLs) of the following groups: KPC, SME, TEM, SHV, CTX-M, CMY, and ACT. VABOMERE is not active against bacteria that produce metallo-beta lactamases or oxacillinases with carbapenemase activity.
In the Phase 3 cUTI trial with VABOMERE, some isolates of E. coli, K. pneumoniae, E. cloacae, C. freundii, P. mirabilis, P. stuartii that produced beta-lactamases, were susceptible to VABOMERE (minimum inhibitory concentration ≤4 mcg /mL). These isolates produced one or more beta-lactamases of the following enzyme groups: OXA (non-carbapenemases), KPC, CTX-M, TEM, SHV, CMY, and ACT.
Some beta-lactamases were also produced by an isolate of K. pneumoniae that was not susceptible to VABOMERE (minimum inhibitory concentration ≥32 mcg/mL). This isolate produced beta-lactamases of the following enzyme groups: CTX-M, TEM, SHV, and OXA.
No cross-resistance with other classes of antimicrobials has been identified. Some isolates resistant to carbapenems (including meropenem) and to cephalosporins may be susceptible to VABOMERE.
Interaction With Other Antimicrobials
In vitro synergy studies have not demonstrated antagonism between VABOMERE and levofloxacin, tigecycline, polymyxin, amikacin, vancomycin, azithromycin, daptomycin, or linezolid.
Activity Against Meropenem Non-susceptible Bacteria In Animal Infection Models
Vaborbactam restored activity of meropenem in animal models of infection (e.g., mouse thigh infection, urinary tract infection and pulmonary infection) caused by some meropenem nonsusceptible KPC-producing Enterobacteriaceae.
Antimicrobial Activity
VABOMERE has been shown to be active against most isolates of the following bacteria, both in vitro and in clinical infections [see INDICATIONS AND USAGE].
Gram-negative bacteria:
- Enterobacter cloacae species complex
- Escherichia coli
- Klebsiella pneumoniae
The following in vitro data are available, but their clinical significance is unknown. At least 90 percent of the following bacteria exhibit an in vitro MIC less than or equal to the susceptible breakpoint for VABOMERE against isolates of a similar genus or organism group. However, the efficacy of VABOMERE in treating clinical infections due to these bacteria has not been established in adequate and well-controlled clinical trials.
Gram-negative bacteria:
- Citrobacter freundii
- Citrobacter koseri
- Enterobacter aerogenes
- Klebsiella oxytoca
- Morganella morganii
- Proteus mirabilis
- Providencia spp.
- Pseudomonas aeruginosa
- Serratia marcescens
Susceptibility Test Methods
For specific information regarding susceptibility test interpretive criteria and associated test methods and quality control standards recognized by FDA for this drug, please see: https://www.fda.gov/STIC.
Clinical Studies
Complicated Urinary Tract Infections (cUTI), Including Pyelonephritis
A total of 545 adults with cUTI, including pyelonephritis were randomized into a double-blind, double dummy, multi-center trial comparing VABOMERE (meropenem 2 grams and vaborbactam 2 grams) to piperacillin/tazobactam (piperacillin 4 grams/tazobactam 0.5 grams) intravenously every 8 hours. Switch to an oral antibacterial drug, such as levofloxacin was allowed after a minimum of 15 doses of IV therapy.
The microbiologically modified intent to treat population (m-MITT) included all randomized patients who received any study drug and had at least 1 baseline uropathogen. Clinical and microbiological response at the end of IV treatment (EOIVT) required both a clinical outcome of cure or improvement and a microbiologic outcome of eradication (all baseline uropathogens at >105 CFU/mL are to be reduced to <104 CFU/mL). Clinical and microbiological response was also assessed at the Test of Cure (TOC) visit (approximately 7 days after completion of treatment) in the m-MITT population and required both a clinical outcome of cure and a microbiological outcome of eradication.
Patient demographic and baseline characteristics were balanced between treatment groups in the m-MITT population. Approximately 93% of patients were Caucasian and 66% were females in both treatment groups. The mean age was 54 years with 32% and 42% patients greater than 65 years of age in VABOMERE and piperacillin/tazobactam treatment groups, respectively. Mean body mass index was approximately 26.5 kg/m² in both treatment groups. Concomitant bacteremia was identified in 12 (6%) and 15 (8%) patients at baseline in VABOMERE and piperacillin/tazobactam treatment groups respectively. The proportion of patients with diabetes mellitus at baseline was 17% and 19% in VABOMERE and piperacillin/tazobactam treatment groups, respectively. The majority of patients (approximately 90%) were enrolled from Europe, and approximately 2% of patients were enrolled from North America. Overall, in both treatment groups, 59% of patients had pyelonephritis and 40% had cUTI, with 21% and 19% of patients having a non-removable and removable source of infection, respectively.
Mean duration of IV treatment in both treatment groups was 8 days and mean total treatment duration (IV and oral) was 10 days; patients with baseline bacteremia could receive up to 14 days of therapy. Approximately 10% of patients in each treatment group in the m-MITT population had a levofloxacin-resistant pathogen at baseline and received levofloxacin as the oral switch therapy. This protocol violation may have impacted the assessment of the outcomes at the TOC visit. These patients were not excluded from the analysis presented in Table 6, as the decision to switch to oral levofloxacin was based on post-randomization factors.
VABOMERE demonstrated efficacy with regard to clinical and microbiological response at the EOIVT visit and TOC visits in the m-MITT population as shown in Table 6.
Table 6: Clinical and Microbiological Response Rates in a Phase 3 Trial of Cuti Including Pyelonephritis (m-MITT Population)
|
VABOMERE n/N (%) |
Piperacillin/ Tazobactam n/N (%) |
Difference (95% CI) |
| Clinical cure or improvement AND microbiological eradication at the End of IV Treatment Visit* |
183/186 (98.4) |
165/175 (94.3) |
4.1%
(0.3%, 8.8%) |
| Clinical cure AND microbiological eradication at the Test of Cure visit approximately 7 days after completion of treatment** |
124/162 (76.5) |
112/153 (73.2) |
3.3%
(-6.2%, 13.0%) |
CI = confidence interval; EOIVT = End of Intravenous Treatment; TOC = Test of Cure
*End of IV Treatment visit includes patients with organisms resistant to piperacillin/tazobactam at baseline
**Test of Cure visit excludes patients with organisms resistant to piperacillin/tazobactam at baseline |
In the m-MITT population, the rate of clinical and microbiological response in VABOMEREtreated patients with concurrent bacteremia at baseline was 10/12 (83.3%).
In a subset of the E. coli and K. pneumoniae isolates, genotypic testing identified certain ESBL groups (e.g., TEM, CTX-M, SHV and OXA) in both treatment groups of the Phase 3 cUTI trial. The rates of clinical and microbiological response were similar in the ESBL-positive and ESBLnegative subset at EOIVT; at TOC, clinical and microbiological response was lower in the ESBL-positive as compared to ESBL-negative subset in both treatment groups.
REFERENCES
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