RECARBRIO Powder for solution for injection Ref.[90474] Active ingredients: Cilastatin Imipemide Imipenem, Cilastatin and Relebactam

For imipenem, the % time of dosing interval that unbound plasma concentrations of imipenem exceed the imipenem/relebactam minimum inhibitory concentration (MIC) (%fT>MIC) against the infecting organism best correlates with antibacterial activity in animal and in vitro models of infection. For relebactam the ratio of the 24-hour unbound plasma relebactam AUC to imipenem/relebactam MIC (fAUC_0–24hr/MIC) best predicts the activity of relebactam in animal and in vitro models of infection.

Cardiac Electrophysiology

At a dose 4.6 times the recommended dose, relebactam does not prolong the QTc interval to a clinically relevant extent.

The steady-state pharmacokinetic parameters of imipenem and relebactam in patients with active bacterial infection with CLcr 90 mL/min or greater following administration of the recommended dosage are summarized in Table 5.

Table 5. Population Pharmacokinetic Model-Based Steady State Mean (±SD) Plasma Pharmacokinetic Parameters of Imipenem and Relebactam After Multiple 30 Minute Intravenous Infusions?footnote? of Imipenem 500 mg/Cilastatin 500 mg and Relebactam 250 mg Every 6 Hours in Patients with CLcr 90 mL/min or Greater:

AUC_0-24hr=area under the concentration time curve from 0 to 24 hours
C_max=maximum concentration
CL=plasma clearance
^* Imipenem/cilastatin and relebactam were administered either as separate infusions given concurrently or as the fixed dose combination (RECARBRIO).

Distribution

The binding of imipenem and cilastatin to human plasma proteins is approximately 20% and 40%, respectively. The binding of relebactam to human plasma proteins is approximately 22% and is independent of concentration at a range of 5 to 50 µM.

The penetration of imipenem and relebactam into pulmonary epithelial lining fluid is similar, with concentrations around 55% and 54% of unbound plasma concentrations of imipenem and relebactam, respectively.

The steady-state volume of distribution of imipenem, cilastatin, and relebactam is 24.3 L, 13.8 L, and 19.0 L, respectively, in subjects following multiple doses infused over 30 minutes every 6 hours.

Elimination

Imipenem and relebactam are eliminated from the body by the kidneys with a mean (±SD) half-life of 1 (±0.5) hour and 1.2 (±0.7) hours, respectively.

Metabolism

Imipenem, when administered alone, is metabolized in the kidneys by dehydropeptidase, resulting in low levels of imipenem recovered in human urine. Cilastatin, an inhibitor of this enzyme, effectively prevents renal metabolism so that when imipenem and cilastatin are given concomitantly, adequate concentrations of imipenem are achieved in the urine to enable antibacterial activity.

Relebactam is minimally metabolized. Unchanged relebactam was the only drug-related component detected in human plasma.

Excretion

Imipenem, cilastatin, and relebactam are mainly excreted by the kidneys.

Following multiple-dose administration of imipenem 500 mg, cilastatin 500 mg, and relebactam 250 mg to healthy male subjects, approximately 63% of the administered imipenem dose, and 77% of the administered cilastatin dose are recovered as unchanged parent drugs in the urine. The renal excretion of imipenem and cilastatin involves both glomerular filtration and active tubular secretion. Greater than 90% of the administered relebactam dose was excreted unchanged in human urine. The unbound renal clearance of relebactam is greater than the glomerular filtration rate, suggesting that in addition to glomerular filtration, active tubular secretion is involved in the renal elimination, accounting for ~30% of the total clearance.

Specific Populations

No clinically significant differences in the pharmacokinetics of imipenem, cilastatin, or relebactam were observed based on age, gender, or race/ethnicity.

Patients with Renal Impairment

In a single-dose trial evaluating the effect of renal impairment on the PK of relebactam 125 mg co-infused with imipenem/cilastatin 250 mg (half the recommended dose in patients with normal renal function), mean AUC was higher in subjects with CLcr 60-89, 30-59, and 15-29 mL/min, respectively, compared to healthy subjects with CLcr 90 mL/min or greater (Table 6). In subjects with end stage renal disease (ESRD) on hemodialysis, imipenem, cilastatin, and relebactam are removed by hemodialysis, with extraction coefficients of 66% to 87% for imipenem, 46% to 56% for cilastatin, and 67% to 87% for relebactam.

Table 6. Mean AUC Increase in Subjects with Renal Impairment Compared to Subjects with CLcr 90 mL/min or Greater:

To maintain systemic exposures similar to patients with normal renal function, dose adjustment is recommended for patients with renal impairment [see Dosage and Administration (2.2)]. ESRD patients on hemodialysis should receive RECARBRIO after hemodialysis session [see Dosage and Administration (2.2)].

Patients with Hepatic Impairment

Imipenem, cilastatin, and relebactam are primarily cleared renally; therefore, hepatic impairment is not likely to have any effect on RECARBRIO exposures.

Drug Interaction Studies

Clinical Studies

No drug-drug interaction was observed among imipenem, cilastatin, and relebactam in a clinical study in healthy subjects.

No clinically significant differences in the pharmacokinetics of imipenem or relebactam were observed when RECARBRIO was used concomitantly with probenecid (Organic Anion Transporter 3 (OAT3) inhibitor).

In Vitro Studies

CYP Enzymes:

Relebactam does not inhibit CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, or CYP3A4 or induce CYP1A2, CYP2B6, or CYP3A4 in human hepatocytes.

Transporter Systems:

Relebactam does not inhibit OATP1B1, OATP1B3, OAT1, OAT3, OCT2, P-gp, BCRP, MATE1, MATE2K, or BSEP.

Relebactam is not a substrate of OAT1, OCT2, P-gp, BCRP, MRP2, or MRP4 transporters, but is a substrate of OAT3, OAT4, MATE1, and MATE2K transporters.

The following antibacterial and antifungal drugs (piperacillin/tazobactam, ciprofloxacin, fluconazole, ampicillin, levofloxacin, metronidazole, vancomycin, linezolid, daptomycin, and cefazolin) did not significantly inhibit OAT3-mediated relebactam uptake.

Mechanism of Action

RECARBRIO is a combination of imipenem/cilastatin and relebactam. Imipenem is a penem antibacterial drug, cilastatin sodium is a renal dehydropeptidase inhibitor, and relebactam is a beta-lactamase inhibitor. Cilastatin limits the renal metabolism of imipenem and does not have antibacterial activity. The bactericidal activity of imipenem results from binding to PBP 2 and PBP 1B in Enterobacteriaceae and Pseudomonas aeruginosa and the subsequent inhibition of penicillin binding proteins (PBPs). Inhibition of PBPs leads to the disruption of bacterial cell wall synthesis. Imipenem is stable in the presence of some beta-lactamases. Relebactam has no intrinsic antibacterial activity. Relebactam protects imipenem from degradation by certain serine beta-lactamases such as Sulfhydryl Variable (SHV), Temoneira (TEM), Cefotaximase-Munich (CTX-M), Enterobacter cloacae P99 (P99), Pseudomonas-derived cephalosporinase (PDC, AmpC-type), and Klebsiella-pneumoniae carbapenemase (KPC).

Resistance

Clinical isolates may produce multiple beta-lactamases, express varying levels of beta-lactamases, have amino acid sequence variations, or have other resistance mechanisms that have not yet been identified. Culture and susceptibility information and local epidemiology should be considered in selecting or modifying antibacterial therapy.

Mechanisms of beta lactam resistance in gram-negative organisms include the production of beta-lactamases, up-regulation of efflux pumps, and loss of outer membrane porins. Imipenem/relebactam retains activity in the presence of the tested efflux pumps. Imipenem/relebactam has shown activity against some isolates of P. aeruginosa and Enterobacteriaceae that produce relebactam-susceptible beta-lactamases concomitant with loss of entry porins. Imipenem/relebactam is not active against most isolates containing metallo-beta-lactamases (MBLs), some oxacillinases with carbapenemase activity, as well as certain alleles of GES.

Imipenem/relebactam demonstrated in vitro activity against some Enterobacteriaceae isolates genotypically characterized for some beta-lactamases and extended-spectrum beta-lactamases (ESBLs) of the following groups: KPC, TEM, SHV, CTX-M, CMY, DHA, and ACT/MIR. Many of the Enterobacteriaceae isolates that were not susceptible to imipenem-relebactam were genotypically characterized and the genes encoding MBLs or certain oxacillinases were present.

Imipenem/relebactam demonstrated in vitro activity against genotypically characterized P. aeruginosa isolates containing certain known resistance factors: some chromosomal PDC alleles with ESBLs, and some with loss of outer membrane porin (OprD) with or without co-expression of up-regulated efflux pumps (MexAB, MexCD, MexJK, and MexXY). Genotypically characterized P. aeruginosa isolates that were not susceptible to imipenem/relebactam encoded some MBL, KPC, PER, GES, VEB, and PDC alleles.

Methicillin-resistant staphylococci should be considered resistant to imipenem. Imipenem is inactive in vitro against Enterococcus faecium, Stenotrophomonas maltophilia, and some isolates of Burkholderia cepacia.

No cross-resistance with other classes of antimicrobials has been identified. Some isolates resistant to carbapenems (including imipenem) and to cephalosporins may be susceptible to RECARBRIO.

Interaction with Other Antimicrobials

In vitro studies have demonstrated no antagonism between imipenem/relebactam and amikacin, azithromycin, aztreonam, colistin, gentamicin, levofloxacin, linezolid, tigecycline, tobramycin, or vancomycin.

Activity against Imipenem-Nonsusceptible Bacteria in Animal Infection Models

Relebactam restored activity of imipenem/cilastatin in animal models of infection (e.g., mouse disseminated infection, mouse thigh infection, and mouse pulmonary infection) caused by imipenem-nonsusceptible KPC-producing Enterobacteriaceae and imipenem-nonsusceptible P. aeruginosa (imipenem-nonsusceptible due to production of chromosomal PDC and loss of OprD porin).

Antimicrobial Activity

RECARBRIO has been shown to be active against most isolates of the following bacteria, both in vitro and in clinical infections [see Indications and Usage (1.1) and (1.2)].

Hospital-acquired Bacterial Pneumonia and Ventilator-associated Bacterial Pneumonia (HABP/VABP)

Aerobic Bacteria:

Gram-negative Bacteria:

Acinetobacter calcoaceticus-baumannii complex
Enterobacter cloacae
Escherichia coli
Haemophilus influenzae
Klebsiella aerogenes
Klebsiella oxytoca
Klebsiella pneumoniae
Pseudomonas aeruginosa
Serratia marcescens

Complicated Urinary Tract Infections (cUTI)

Aerobic Bacteria:

Gram-negative Bacteria:

Klebsiella aerogenes
Enterobacter cloacae
Escherichia coli
Klebsiella pneumoniae
Pseudomonas aeruginosa

Complicated Intra-abdominal Infections (cIAI)

Aerobic Bacteria:

Gram-negative Bacteria:

Citrobacter freundii
Klebsiella aerogenes
Enterobacter cloacae
Escherichia coli
Klebsiella oxytoca
Klebsiella pneumoniae
Pseudomonas aeruginosa

Anaerobic Bacteria:

Gram-negative Bacteria:

Bacteroides caccae
Bacteroides fragilis
Bacteroides ovatus
Bacteroides stercoris
Bacteroides thetaiotaomicron
Bacteroides uniformis
Bacteroides vulgatus
Fusobacterium nucleatum
Parabacteroides distasonis

The following in vitro data are available, but their clinical significance is unknown. At least 90% of the following bacteria exhibit an in vitro MIC less than or equal to the susceptible breakpoint for RECARBRIO against isolates of similar genus or organism group. However, the efficacy of RECARBRIO in treating clinical infections due to these bacteria has not been established in adequate and well-controlled clinical trials.

Aerobic Bacteria:

Gram-positive Bacteria:

Enterococcus faecalis
Methicillin-susceptible Staphylococcus aureus
Streptococcus anginosus
Streptococcus constellatus
Streptococcus pneumoniae

Gram-negative Bacteria:

Citrobacter koseri
Enterobacter asburiae

Anaerobic Bacteria:

Gram-positive Bacteria:

Eggerthella lenta
Parvimonas micra
Peptoniphilus harei
Peptostreptococcus anaerobius

Gram-negative Bacteria:

Fusobacterium necrophorum
Fusobacterium varium
Parabacteroides goldsteinii
Parabacteroides merdae
Prevotella bivia
Veillonella parvula

Susceptibility Test Methods

For specific information regarding susceptibility testing methods, interpretive criteria, and associated test methods and quality control standards recognized by FDA for RECARBRIO, please see: https://www.fda.gov/STIC.

Carcinogenesis

Carcinogenicity studies with imipenem/cilastatin or relebactam have not been conducted.

Mutagenesis

Genotoxicity studies were performed in a variety of bacterial and mammalian tests in vivo and in vitro. None of these tests showed any evidence of genetic damage.

The tests conducted with imipenem, cilastatin, or imipenem/cilastatin included: V79 mammalian cell mutagenesis assay (imipenem, cilastatin), Ames test (imipenem, cilastatin), unscheduled DNA synthesis assay (imipenem/cilastatin), and in vivo mouse cytogenetics test (imipenem/cilastatin).

The tests conducted with relebactam included: Ames test, in vitro chromosomal aberration in Chinese Hamsters Ovary (CHO) cells, and in vivo rat micronucleus test.

Impairment of Fertility

No adverse effects on fertility, reproductive performance, fetal viability, growth or postnatal development were observed in male and female rats given imipenem/cilastatin at intravenous doses up to 80 mg/kg/day and at a subcutaneous dose of 320 mg/kg/day. In rats, a dose of 320 mg/kg was approximately double the MRHD based on body surface area. Slight decreases in live fetal body weight were restricted to the highest dosage level.

In fertility studies, relebactam was administered in intravenous doses of 50, 150, and 450 mg/kg/day to male rats beginning 15 days before mating, through mating, and for an additional 3 weeks and to female rats beginning 15 days before mating, through mating, and until gestation day (GD) 7. Relebactam did not impair fertility, reproductive performance or spermatogenesis in males or fertility, reproductive performance, or early embryonic development in females at doses up to 450 mg/kg/day corresponding to plasma AUC exposures of approximately 8 times in males and 7 times in females the plasma AUC exposure in humans at the MRHD.

Relebactam given as a single entity caused renal tubular degeneration in monkeys at AUC exposure 7-fold the human AUC exposure at the MRHD. Renal tubular degeneration was shown to be reversible after dose discontinuation. There was no evidence of nephrotoxicity at AUC exposures less than or equal to 3-fold the human AUC exposure at the MRHD.

14.1 Hospital-acquired Bacterial Pneumonia and Ventilator-associated Bacterial Pneumonia

A total of 535 hospitalized adults with HABP/VABP were randomized and received trial medications in a multinational, double-blind trial (Trial 1, NCT02493764) comparing RECARBRIO 1.25 grams (imipenem 500 mg/cilastatin 500 mg/relebactam 250 mg) intravenously every 6 hours to piperacillin and tazobactam (4.5 grams) for 7 to 14 days of therapy.

The modified intent-to-treat (MITT) population, which included all randomized patients who received at least one dose of trial treatment and did not have only gram-positive cocci on Gram stain of the baseline lower respiratory tract (LRT) specimen included 531 patients; the mean age was 60 and 43% were 65 years of age or older. The majority of patients were men (69%), white (78%), and from Europe (61%). The mean APACHE II score was 15 and 47% of the population had an APACHE II score of ≥15. At randomization, 66% of patients were admitted to the ICU, 77% had been in the hospital for ≥5 days, and 48% had a creatinine clearance of <90 mL/min. Concurrent bacteremia was present at baseline in 5.8% of patients.

Table 7 presents the incidence of all-cause mortality through Day 28 and clinical response at the early follow-up (EFU) visit (7 to 14 days after the end of therapy) in the MITT population. Overall results are presented along with subgroup results by pneumonia diagnosis.

Table 7. Day 28 All-Cause Mortality and Clinical Response Rates at EFU from Trial 1 of Hospital-acquired Bacterial Pneumonia and Ventilator-associated Bacterial Pneumonia (HABP/VABP) (MITT Population):

EFU = early follow up
^* Treatment differences and 95% confidence intervals are based on Miettinen & Nurminen method.
^† n/m = number of subjects with survival status of death or unknown / number of modified intentto-treat subjects.
^‡ One subject in the RECARBRIO arm had unknown mortality status at Day 28 which was counted as a death.
^§ n/m = number of subjects with a favorable clinical response / number of modified intent-to-treat subjects.

In the MITT population, in patients with an APACHE II score <15, Day 28 all-cause mortality rates were 17/139 (12.2%) for RECARBRIO-treated patients and 12/140 (8.6%) for piperacillin/tazobactam-treated patients, clinical cure rates were 90/139 (64.7%) and 98/140 (70%), respectively. In patients with an APACHE II score ≥15, Day 28 all-cause mortality rates were 25/125 (20%) for RECARBRIO-treated patients and 45/127 (35.4%) for piperacillin/tazobactam-treated patients, clinical cure rates were 71/125 (56.8%) and 51/127 (40.2%), respectively.

Per pathogen favorable clinical response at EFU and Day 28 all-cause mortality were assessed in a microbiological modified intention to treat (mMITT) population, which consisted of all randomized MITT subjects who had at least one baseline LRT pathogen that was susceptible to both study treatments (Table 8).

Table 8. Day 28 All-Cause Mortality and Favorable Clinical Response at EFU by Baseline LRT Pathogen from Trial 1 of Hospital-acquired Bacterial Pneumonia and Ventilator-associated Bacterial Pneumonia (HABP/VABP) (mMITT Population):

LRT = lower respiratory tract
EFU = early follow-up
^* n/m = the number of subjects with survival status of death or unknown within each category / the number of microbiological modified intent-to-treat subjects who have the corresponding baseline pathogen from LRT culture.
^† n/m = the number of subjects with a favorable clinical response within each category / the number of microbiological modified intent-to-treat subjects who have the corresponding baseline pathogen from LRT culture
^‡ Supportive evidence was derived from the imipenem and cilastatin prescribing information.
^§ All H. influenzae isolates were susceptible to imipenem. The susceptible MIC breakpoint for PIP/TAZ is ≤1/4 mcg/mL. At the lowest concentration of PIP/TAZ tested (2/4 mcg/mL) there was no visible growth.
^¶ Includes Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae.

14.2 Complicated Urinary Tract Infections, including Pyelonephritis and Complicated Intra-abdominal Infections

The determination of efficacy and safety of RECARBRIO was supported in part by the previous findings of the efficacy and safety of imipenem/cilastatin for the treatment of cUTI and cIAI. The contribution of relebactam to RECARBRIO was primarily established in vitro and in animal models of infection [see Microbiology (12.4)]. Imipenem/cilastatin plus relebactam was studied in cUTI including pyelonephritis (Trial 2, NCT01505634) and cIAI (Trial 3, NCT01506271) in randomized, blinded, active-controlled, multicenter trials. These trials provided only limited efficacy and safety information.