Safety, Pharmacokinetics, and Food Effect of Tebipenem Pivoxil Hydrobromide after Single and Multiple Ascending Oral Doses in Healthy Adult Subjects

Current state and novel outlook on prevention and treatment of rising antibiotic resistance in urinary tract infections

Antibiotic-resistant bacteria are currently an important public health concern posing a serious threat due to their resistance to the current arsenal of antibiotics. Uropathogens Escherichia coli (UPEC), Proteus mirabilis, Klebsiella pneumoniae and Enterococcus faecalis, antibiotic-resistant gram-negative bacteria, cause serious cases of prolonged UTIs, increasing healthcare costs and potentially even leading to the death of an affected patient. This review discusses current knowledge about the increasing resistance to currently recommended antibiotics for UTI therapy, as well as novel therapeutic options. Traditional antibiotics are still a part of the therapy guidelines for UTIs, although they are often not effective and have serious side effects. Hence, novel drugs are being developed, such as combinations of β-lactam antibiotics with cephalosporins and carbapenems. Siderophoric cephalosporins, such as cefiderocol, have shown potential in the treatment of individuals with significant gram-negative bacterial infections, as well as aminoglycosides, fluoroquinolones and tetracyclines that are also undergoing clinical trials. The use of cranberry and probiotics is another potential curative and preventive method that has shown antimicrobial and anti-inflammatory effects. However, further studies are needed to assess the efficacy and safety of probiotics containing cranberry extract for UTI prevention and treatment. An emerging novel approach for UTI treatment is the use of immuno-prophylactic vaccines, as well as different nanotechnology solutions such as nanoparticles (NP). NP have the potential to be used as delivery systems for drugs to specific targets. Furthermore, nanotechnology could enable the development of nano antibiotics with improved features by the application of different NPs in their structure, such as gold and copper NPs. However, further high-quality research is required for the synthesis and testing of these novel molecules, such as safety evaluation and pharmacovigilance.

Oral β-Lactam Pairs for the Treatment of Mycobacterium avium Complex Pulmonary Disease

Cure rates for pulmonary disease caused by the Mycobacterium avium complex (MAC) are poor. While β-lactam are front line antibiotics against Mycobacterium abscessus pulmonary disease, they have not been used or recommended to treat MAC lung infections. Through a comprehensive screen of oral β-lactams, we have discovered that selected pairs combining either a penem/carbapenem or penicillin with a cephalosporin are strongly bactericidal at clinically achieved concentrations. These dual β-lactam combinations include tebipenem and sulopenem, both in phase 3, and Food and Drug Administration-approved amoxicillin and cefuroxime. They could therefore immediately enter clinical trials or clinical practice.

Upholding or Breaking the Law of Superposition in Pharmacokinetics

The law of superposition underpins first-order linear pharmacokinetic relationships. Most drugs, therefore, after a single dose can be described by first-order or linear processes, which can be superposed to understand multiple-dose regimen behavior. However, there are a number of situations where drugs could display behaviors after multiple dosing that leads to capacity-limited or saturation non-linear kinetics and the law of superposition is overruled. This review presents a practical guide to understand the equations and calculations for single and multiple-dosing regimens after intravenous and oral administration. It also provides the pharmaceutical basis for saturation in ADME processes and the consequent changes in the area under the concentration-time curve, which represents drug exposure that can lead to the modulation of efficacy and/or toxic effects. The pharmacokineticist must implicitly understand the principles of superposition, which are a central tenet of drug behavior and disposition during drug development.

A pairwise approach to revitalize β-lactams for the treatment of TB

The dual β-lactam approach has been successfully applied to overcome target redundancy in nontuberculous mycobacteria. Surprisingly, this approach has not been leveraged for Mycobacterium tuberculosis, despite the high conservation of peptidoglycan synthesis. Through a comprehensive screen of oral β-lactam pairs, we have discovered that cefuroxime strongly potentiates the bactericidal activity of tebipenem and sulopenem-advanced clinical candidates-and amoxicillin, at concentrations achieved clinically. β-lactam pairs thus have the potential to reduce TB treatment duration.

Do dietary interventions exert clinically important effects on the bioavailability of β-lactam antibiotics? A systematic review with meta-analyses

BACKGROUND

Managing drug-food interactions may help to achieve the optimal action and safety profile of β-lactam antibiotics.

METHODS

We conducted a systematic review with meta-analyses in adherence to PRISMA guidelines for 32 β-lactams. We included 166 studies assessing the impact of food, beverages, antacids or mineral supplements on the pharmacokinetic (PK) parameters or PK/pharmacodynamic (PK/PD) indices.

RESULTS

Eighteen of 25 β-lactams for which data on food impact were available had clinically important interactions. We observed the highest negative influence of food (AUC or Cmax decreased by >40%) for ampicillin, cefaclor (immediate-release formulations), cefroxadine, cefradine, cloxacillin, oxacillin, penicillin V (liquid formulations and tablets) and sultamicillin, whereas the highest positive influence (AUC or Cmax increased by >45%) for cefditoren pivoxil, cefuroxime and tebipenem pivoxil (extended-release tablets). Significantly lower bioavailability in the presence of antacids or mineral supplements occurred for 4 of 13 analysed β-lactams, with the highest negative impact for cefdinir (with iron salts) and moderate for cefpodoxime proxetil (with antacids). Data on beverage impact were limited to 11 antibiotics. With milk, the extent of absorption was decreased by >40% for cefalexin, cefradine, penicillin G and penicillin V, whereas it was moderately increased for cefuroxime. No significant interaction occurred with cranberry juice for two tested drugs (amoxicillin and cefaclor).

CONCLUSIONS

Factors such as physicochemical features of antibiotics, drug formulation, type of intervention, and patient's health state may influence interactions. Due to the poor actuality and diverse methodology of included studies and unproportionate data availability for individual drugs, we judged the quality of evidence as low.

Impact of antibiotic pharmacokinetics in urine on recurrent bacteriuria following treatment of complicated urinary tract infections

The clinical relevance of bacteriuria following antibiotic treatment of complicated urinary tract infections in clinical trials remains controversial. We evaluated the impact of urine pharmacokinetics on the timing of recurrent bacteriuria in a recently completed trial that compared oral tebipenem pivoxil hydrobromide to intravenous ertapenem. The urinary clearance and urine dwell time of ertapenem were prolonged relative to tebipenem and were associated with a temporal difference in the repopulation of bladder urine with bacteria following treatment, potentially confounding the assessment of efficacy.

Population Pharmacokinetic Analyses for Tebipenem after Oral Administration of Pro-Drug Tebipenem Pivoxil Hydrobromide

Tebipenem pivoxil hydrobromide (TBP-PI-HBr) is an oral (PO) carbapenem pro-drug that is converted to the active moiety tebipenem in the enterocytes. Tebipenem has activity against multidrug-resistant Gram-negative pathogens, including extended-spectrum beta lactamase-producing Enterobacterales, and is being developed for the treatment of patients with complicated urinary tract infections (cUTI) and acute pyelonephritis (AP). The objectives of these analyses were to develop a population pharmacokinetic (PK) model for tebipenem using data from three phase 1 studies and one phase 3 study and to identify covariates that described the variability in tebipenem PK. Following construction of the base model, a covariate analysis was conducted. The model was then qualified by performing a prediction-corrected visual predictive check and evaluated by using a sampling-importance-resampling procedure. The final population PK data set was composed of data from 746 subjects who provided 3,448 plasma concentrations, including 650 patients (1,985 concentrations) with cUTI/AP. The final population PK model that best described tebipenem PK was found to be a two-compartment model with linear, first-order elimination and two transit compartments to describe the rate of drug absorption after PO administration of TBP-PI-HBr. The relationship between renal clearance (CLR) and creatinine clearance (CLcr), the most clinically significant covariate, was described using a sigmoidal Hill-type function. No dose adjustments are warranted on the basis of age, body size, or sex as none of these covariates were associated with substantial differences in tebipenem exposure in patients with cUTI/AP. The resultant population PK model is expected to be appropriate for model-based simulations and assessment of pharmacokinetic-pharmacodynamic relationships for tebipenem.

Absorption, Metabolism, and Excretion of [14C]-Tebipenem Pivoxil Hydrobromide (TBP-PI-HBr) in Healthy Male Subjects

Tebipenem pivoxil hydrobromide (TBP-PI-HBr) is an oral prodrug of pharmacologically active moiety tebipenem (TBP), which is a carbapenem with activity against multidrug-resistant Gram-negative pathogens. Conversion from the prodrug to the active moiety, namely, TBP, occurs in the enterocytes of the gastrointestinal tract via intestinal esterases. The absorption, metabolism, and excretion in humans were evaluated, following the administration of a single oral dose of [14C]-TBP-PI-HBr. Healthy male subjects (n = 8) received a single 600 mg oral dose of TBP-PI-HBr containing approximately 150 μCi of [14C]-TBP-PI-HBr. Blood, urine, and fecal samples were collected to determine the total radioactivity, concentrations of TBP (plasma only), and metabolite profiling and identification. The overall mean recovery of the total radioactivity in urine (38.7%) and feces (44.6%) combined was approximately 83.3% of the administered dose, with individual recoveries ranging from 80.1% to 85.0%. Plasma TBP LC-MS/MS and metabolite profiling data suggest that TBP was the main circulating component in plasma and that it accounts for approximately 54% of the total plasma radioactivity, based on the plasma AUC ratio of TBP/total radioactivity. The ring-open metabolite LJC 11562 was another major component in plasma (>10%). TBP (M12), LJC 11562, and four trace to minor metabolites were identified/characterized in the urine. TBP-PI, TBP (M12), and 11 trace to minor metabolites were identified/characterized in the feces. The renal and fecal routes are major clearance pathways in the elimination of [14C]-TBP-PI-HBr, with a mean combined recovery of 83.3%. TBP and its inactive ring-open metabolite LJC 11562 were the major circulating metabolites in the plasma.

Effect of an Antacid (Aluminum Hydroxide/Magnesium Hydroxide/Simethicone) or a Proton Pump Inhibitor (Omeprazole) on the Pharmacokinetics of Tebipenem Pivoxil Hydrobromide (TBP-PI-HBr) in Healthy Adult Subjects

Tebipenem pivoxil hydrobromide (TBP-PI-HBr) is a novel oral carbapenem prodrug being developed for the treatment of serious bacterial infections. This open-label, 3-period, fixed sequence study evaluated the effect of gastric acid-reducing agents, aluminum hydroxide/magnesium hydroxide/simethicone, and omeprazole on the pharmacokinetics (PK) of tebipenem (TBP), the active moiety, following coadministration with immediate release TBP-PI-HBr during fasting. In Period 1, subjects received a single oral dose of TBP-PI-HBr 600 mg (2 × 300 mg tablets). In Period 2, subjects received a single oral dose of aluminum hydroxide 800 mg/magnesium hydroxide 800 mg/simethicone 80 mg suspension co-administered with a single dose of TBP-PI-HBr 600 mg. In Period 3, subjects received a single oral dose of omeprazole 40 mg once daily over 5 days, followed by single dose administration of TBP-PI-HBr 600 mg on day 5. In each period, whole blood samples were obtained prior to, and up to 24 h, following TBP-PI-HBr dose administration in order to characterize TBP PK. A 7-day washout was required between periods. Twenty subjects were enrolled and completed the study. Following co-administration of TBP-PI-HBr with either aluminum hydroxide/magnesium hydroxide/simethicone or omeprazole, total TBP exposure (area under the curve [AUC]) was approximately 11% (geometric mean ratio 89.2, 90% confidence interval: 83,2, 95.7) lower, and Cmax was 22% (geometric mean ratio 78.4, 90% confidence interval: 67.9, 90.6) and 43% (geometric mean ratio 56.9, 90% confidence interval: 49.2, 65.8) lower, respectively, compared to administration of TBP-PI-HBr alone. Mean TBP elimination half-life (t_1/2) was generally comparable across treatments (range: 1.0 to 1.5 h). Concomitant administration of TBP-PI-HBr with omeprazole or aluminum hydroxide/magnesium hydroxide/simethicone is not expected to impact the efficacy of TBP-PI-HBr, as there is minimal impact on TBP plasma AUC, which is the pharmacodynamic driver of efficacy. Co-administration was generally safe and well tolerated.

Evaluation of Oral Tebipenem as a Step-Down Therapy following Intravenous Ertapenem against Extended-Spectrum β-Lactamase-Producing Escherichia coli in a Hollow-Fiber In Vitro Infection Model

Tebipenem is an orally bioavailable carbapenem in development for the treatment of patients with complicated urinary tract infections. Herein, we describe the results of studies designed to evaluate tebipenem's potential as an oral (p.o.) transition therapy from intravenous (i.v.) ertapenem therapy for the most common uropathogen, Escherichia coli. These studies utilized a 7-day hollow-fiber in vitro infection model and 5 extended-spectrum β-lactamase-producing E. coli challenge isolates. Human free-drug serum concentration-time profiles for tebipenem 600 mg p.o. every 8 h and ertapenem 1 g i.v. every 24 h were simulated in the hollow-fiber in vitro infection model. Samples were collected for bacterial density and drug concentration determination over the 7-day study period. Generally, ertapenem monotherapy resulted in a greater reduction in bacterial density than did tebipenem monotherapy. In the treatment arms in which ertapenem dosing was stopped following dosing for 1 or 3 days, immediate bacterial regrowth occurred and matched that of the growth control. Finally, in the treatment arms in which ertapenem dosing was stopped following dosing for 1 or 3 days and tebipenem dosing was initiated for the remainder of the 7-day study, the intravenous-to-oral transition regimen reduced bacterial burdens and prevented regrowth. Given that transition from intravenous to oral antibiotic therapy has been shown to reduce hospital length of stay, nosocomial infection risk, and cost, and improve patient satisfaction, these data demonstrate tebipenem's potential role as an oral transition agent from intravenous antibiotic regimens within the antibiotic stewardship paradigm.

Pharmacokinetics and soft-tissue distribution of tebipenem pivoxil hydrobromide using microdialysis: a study in healthy subjects and patients with diabetic foot infections

OBJECTIVE

Tebipenem pivoxil hydrobromide is a novel oral carbapenem prodrug of tebipenem, the active moiety. We assessed tebipenem steady-state pharmacokinetics in the skin and soft tissue in healthy subjects and infected patients with diabetes using in vivo microdialysis.

METHODS

Six healthy subjects and six patients with an ongoing diabetic foot infection (DFI) received tebipenem pivoxil hydrobromide 600 mg orally every 8 h for three doses. A microdialysis probe was inserted in the thigh of healthy subjects or by the wound margin in patients. Plasma and dialysate samples were obtained immediately prior to the third dose and sampled over 8 h.

RESULTS

Tebipenem plasma protein binding (mean ± SD) was 50.2% ± 2.4% in healthy subjects and 53.5% ± 5.6% in infected patients. Mean ± SD tebipenem pharmacokinetic parameters in plasma for healthy subjects and infected patients were: maximum free concentration (fCmax), 3.74 ± 2.35 and 3.40 ± 2.86 mg/L, respectively; half-life, 0.88 ± 0.11 and 2.02 ± 1.32 h; fAUC0-8, 5.61 ± 1.64 and 10.01 ± 4.81 mg·h/L. Tebipenem tissue AUC0-8 was 5.99 ± 3.07 and 8.60 ± 2.88 mg·h/L for healthy subjects and patients, respectively. The interstitial concentration-time profile largely mirrored the free plasma profile within both populations, resulting in a penetration ratio of 107% in healthy subjects and 90% in infected patients.

CONCLUSIONS

Tebipenem demonstrated excellent distribution into skin and soft tissue of healthy subjects and patients with DFI following oral administration of 600 mg of tebipenem pivoxil hydrobromide.

Relative bioavailability of crushed tebipenem administered through a nasogastric tube with and without enteral feeding

OBJECTIVE

Tebipenem pivoxil hydrobromide is an orally bioavailable carbapenem prodrug of the active agent tebipenem with broad-spectrum activity against drug-resistant Enterobacterales. This study aimed to evaluate the relative bioavailability of crushed tebipenem tablets administered via nasogastric tube (NGT) with or without concomitant enteral feeds.

METHODS

This Phase 1, open label study randomized 12 healthy subjects to receive a crushed tebipenem tablet via NGT (n = 6) or via NGT with concomitant Osmolite® enteral feeds (n = 6) on Study Day 1, followed by oral administration of tebipenem whole tablet (reference formulation) on Study Day 2. Tebipenem plasma concentrations were measured by LC with mass spectrometry. Bioequivalence was determined using pharmacokinetic parameters derived through non-compartmental analyses.

RESULTS

Mean ± SD tebipenem pharmacokinetic parameters in plasma for subjects who received a crushed tablet via NGT (relative to whole tablet) and a crushed tablet with enteral feeds (relative to whole tablet) were as follows: maximum total plasma concentration (Cmax), 11.1 ± 3.9 (12 ± 3.4) and 10.2 ± 1.9 (10 ± 4) mg/L; area under the curve (AUC0-8), 17.5 ± 3.5 (17.9 ± 2.3) and 15 ± 4.3 (13.4 ± 5.3) mg•h/L. Using the 90% CI criteria, Cmaxand AUC0-8 values for tebipenem were found to be bioequivalent following alternative methods of administration compared with oral dosing of the whole tablet. The three methods of administration were well tolerated.

CONCLUSION

Results demonstrate that tebipenem maintained bioequivalence when crushed and administered via NGT with and without accompanying enteral feeds in healthy subjects, relative to whole tablet oral administration. Data therefore support alternative methods of tebipenem administration depending on patient condition.

Novel agents in development for multidrug-resistant Gram-negative infections: potential new options facing multiple challenges

PURPOSE OF REVIEW

To review novel antiinfective agents in development for multidrug-resistant (MDR) Gram-negative bacterial infections.

RECENT FINDINGS

Four novel agents are in various phases of development (tebipenem, durlobactam-sulbactam, cefepime-taniborbactam, and xeruborbactam). Tebpipenem is an oral carbapenem with a recently completed phase III trial for complicated urinary tract infections while durlobactam-sulbactam represents a potential alternative for drug-resistant Acinetobacter baumannii . Cefepime-taniborbactam possesses in-vitro potency against a range of troubling pathogens and we await further information on a recently completed study on complicated urinary tract infection. Finally, xeruborbactam is an ultrabroad beta-lactamase inhibitor that can be paired with a range of intravenous and oral agents. It exhibits enhanced in-vitro activity against many MDR pathogens, including those resistant to newer, broader spectrum options. Data in humans with xeruborbactam are limited.

SUMMARY

Each of the newer options reviewed possesses a unique range of in-vitro activity against select, challenging pathogens with some narrowly tailored and other broader in activity. Several have both oral and intravenous formulations. Two agents have presented data from recent phase III trials, whereas two are not as advanced in their clinical programs.

Plasma and Intrapulmonary Concentrations of Tebipenem following Oral Administration of Tebipenem Pivoxil Hydrobromide to Healthy Adult Subjects

Tebipenem pivoxil hydrobromide (TBP-PI-HBr) is an oral carbapenem prodrug being developed for the treatment of serious bacterial infections. The active moiety, tebipenem, has broad-spectrum activity against common Enterobacterales pathogens, including extended-spectrum-β-lactamase (ESBL)-producing multidrug-resistant strains. This study evaluated the intrapulmonary pharmacokinetics (PK) and epithelial lining fluid (ELF) and alveolar macrophage (AM) concentrations of tebipenem relative to plasma levels in nonsmoking, healthy adult subjects. Thirty subjects received oral TBP-PI-HBr at 600 mg every 8 h for five doses. Serial blood samples were collected following the last dose. Each subject underwent one standardized bronchoscopy with bronchoalveolar lavage (BAL) 1, 2, 4, 6, or 8 h after the fifth dose of TBP-PI-HBr. The tebipenem area under the concentration-time curve for the 8-h dosing interval (AUC_0-8) values in plasma, ELF, and AMs were calculated using the mean concentration at each BAL sampling time. Ratios of AUC_0-8 values for total ELF and AMs to those for unbound plasma were determined, using a plasma protein binding value of 42%. Mean values ± standard deviations (SD) of tebipenem maximum (C_max) and minimum (C_min) total plasma concentrations were 11.37 ± 3.87 mg/L and 0.043 ± 0.039 mg/L, respectively. Peak tebipenem concentrations in plasma, ELF, and AMs occurred at 1 h and then decreased over 8 h. Ratios of tebipenem AUC_0-8 values for ELF and AMs to those for unbound plasma were 0.191 and 0.047, respectively. Four (13.3%) subjects experienced adverse events (diarrhea, fatigue, papule, and coronavirus disease 2019 [COVID-19]); all resolved, and none were severe or serious. Tebipenem is distributed into the lungs of healthy adults, which supports the further evaluation of TBP-PI-HBr for the treatment of lower respiratory tract bacterial infections caused by susceptible pathogens. (This study has been registered at ClinicalTrials.gov under identifier NCT04710407.).

Evaluation of Tebipenem Hydrolysis by β-Lactamases Prevalent in Complicated Urinary Tract Infections

Tebipenem pivoxil is the first orally available carbapenem antibiotic and has been approved in Japan for treating ear, nose, and throat and respiratory infections in pediatric patients. Its active moiety, tebipenem, has shown potent antimicrobial activity in vitro against clinical isolates of Enterobacterales species from patients with urinary tract infections (UTIs), including those producing extended-spectrum β-lactamases (ESBLs) and/or AmpC β-lactamase. In the present study, tebipenem was tested for stability to hydrolysis by a set of clinically relevant β-lactamases, including TEM-1, AmpC, CTX-M, OXA-48, KPC, and NDM-1 enzymes. In addition, hydrolysis rates of other carbapenems, including imipenem, meropenem, and ertapenem, were determined for comparison. It was found that, similar to other carbapenems, tebipenem was resistant to hydrolysis by TEM-1, CTX-M, and AmpC β-lactamases but was susceptible to hydrolysis by KPC, OXA-48, and NDM-1 enzymes with catalytic efficiency values (k_cat/K_m) ranging from 0.1 to 2 × 10⁶ M^-1s^-1. This supports the reported results of antimicrobial activity of tebipenem against ESBL- and AmpC-producing but not carbapenemase-producing Enterobacterales isolates. Considering that CTX-M and AmpC β-lactamases represent the primary determinants of multidrug-resistant complicated UTIs (cUTIs), the stability of tebipenem to hydrolysis by these enzymes supports the utility of its prodrug tebipenem, tebipenem pivoxil hydrobromide (TBP-PI-HBr), as an oral therapy for adult cUTIs.

Pharmacokinetics of Oral Tebipenem Pivoxil Hydrobromide in Subjects with Various Degrees of Renal Impairment

Tebipenem pivoxil hydrobromide (TBP-PI-HBr) is an oral carbapenem prodrug antimicrobial agent with broad-spectrum activity that includes multidrug-resistant (MDR) Enterobacterales. This study evaluated the safety, tolerability, and pharmacokinetics of TBP-PI-HBr in healthy subjects with normal renal function (cohort 1) and subjects with various degrees of renal impairment (RI [cohorts 2 to 4]) or end-stage renal disease (ESRD) receiving hemodialysis (HD) (cohort 5). Subjects in cohorts 1 to 4 received a single oral dose of TBP-PI-HBr (600 mg). Subjects in cohort 5 received single-dose administration (600 mg) in 2 separate periods: pre-HD (period 2) and post-HD (period 1). Pharmacokinetic (PK) parameters for TBP, the active moiety, were determined using noncompartmental analysis. Compared with cohort 1, the TBP plasma area under the curve (AUC) increased 1.4- to 4.5-fold among cohorts 2 to 4, the maximum concentration of drug in plasma (C_max) increased up to 1.3-fold and renal clearance (CL_R) decreased from 13.4 L/h to 2.4 L/h as the severity of RI increased. Plasma TBP concentrations decreased over 8 to 12 h in cohorts 1 to 4, and apparent total body clearance (CL/F) correlated (R² = 0.585) with creatinine clearance (CL_CR). TBP urinary excretion ranged from 38% to 64% of the administered dose for cohorts 1 to 4. Subjects in cohort 5 had an approximately 7-fold increase in TBP AUC and elimination half-life (t_1/2) versus cohort 1. After 4 h of HD, mean TBP plasma exposure decreased by approximately 40%. Overall, TBP plasma exposure increased with increasing RI, highlighting the renal route importance in TBP elimination. A dose reduction of TBP-PI-HBr may be needed in patients with RI (CL_CR of ≤50 mL/min) and those with ESRD on HD. TBP-PI-HBr was well tolerated across all cohorts. (This study has been registered at ClinicalTrials.gov under registration no. NCT04178577.).

Bioequivalence of Two Oral Formulations of Tebipenem Pivoxil Hydrobromide in Healthy Subjects

Tebipenem pivoxil hydrobromide (TBP-PI-HBr) is a novel oral carbapenem prodrug of tebipenem (TBP), the active moiety, currently in development for treating serious bacterial infections. This study assessed the bioequivalence (BE) of the clinical trial and registration tablet formulations of TBP-PI-HBr and evaluated the effect of food on the pharmacokinetics (PK) of tebipenem. This was a single center, open-label, randomized, single-dose, 3-sequence, 4-period crossover, BE and food-effect study. Subjects received single 600 mg oral doses of TBP-PI-HBr as the reference clinical trial tablet (Treatment A) and test registration tablet (Treatment B) formulations in alternating sequence while fasting, and then the test formulation under fed conditions. Whole blood samples were collected predose and at specified intervals up to 24 hours postdose to evaluate TBP PK parameters. Safety and tolerability were monitored. Thirty-six healthy, adult subjects were enrolled and completed the study. The criteria for bioequivalence were met for the TBP-PI-HBr test (registration tablet) and reference (clinical trial tablet) formulations as the 90% confidence intervals (CIs) for the geometric mean ratios for TBP AUC_0-t , AUC_0-inf , and C_max fell within the established 80% to 125% BE limits. Dosing with food had no meaningful effect on TBP PK parameters. Five (14%) subjects reported adverse events of mild severity. No deaths, serious AEs or discontinuations due to AEs were reported, and no clinically relevant ECGs, vital signs or safety laboratory findings were observed. Results demonstrate the bioequivalence of oral TBP-PI-HBr registration and clinical trial tablet formulations and indicate that TBP-PI-HBr can be administered without regard to meals.

The repurposing of Tebipenem pivoxil as alternative therapy for severe gastrointestinal infections caused by extensively drug-resistant Shigella spp

Background

Diarrhoea remains one of the leading causes of childhood mortality globally. Recent epidemiological studies conducted in low-middle income countries (LMICs) identified Shigella spp. as the first and second most predominant agent of dysentery and moderate diarrhoea, respectively. Antimicrobial therapy is often necessary for Shigella infections; however, we are reaching a crisis point with efficacious antimicrobials. The rapid emergence of resistance against existing antimicrobials in Shigella spp. poses a serious global health problem.

Methods

Aiming to identify alternative antimicrobial chemicals with activity against antimicrobial resistant Shigella, we initiated a collaborative academia-industry drug discovery project, applying high-throughput phenotypic screening across broad chemical diversity and followed a lead compound through in vitro and in vivo characterisation.

Results

We identified several known antimicrobial compound classes with antibacterial activity against Shigella. These compounds included the oral carbapenem Tebipenem, which was found to be highly potent against broadly susceptible Shigella and contemporary MDR variants for which we perform detailed pre-clinical testing. Additional in vitro screening demonstrated that Tebipenem had activity against a wide range of other non-Shigella enteric bacteria. Cognisant of the risk for the development of resistance against monotherapy, we identified synergistic behaviour of two different drug combinations incorporating Tebipenem. We found the orally bioavailable prodrug (Tebipenem pivoxil) had ideal pharmacokinetic properties for treating enteric pathogens and was effective in clearing the gut of infecting organisms when administered to Shigella-infected mice and gnotobiotic piglets.

Conclusions

Our data highlight the emerging antimicrobial resistance crisis and shows that Tebipenem pivoxil (licenced for paediatric respiratory tract infections in Japan) should be accelerated into human trials and could be repurposed as an effective treatment for severe diarrhoea caused by MDR Shigella and other enteric pathogens in LMICs.

Funding

Tres Cantos Open Lab Foundation (projects TC239 and TC246), the Bill and Melinda Gates Foundation (grant OPP1172483) and Wellcome (215515/Z/19/Z).

Tebipenem pivoxil hydrobromide-No PICC, no problem!

Tebipenem pivoxil hydrobromide is a novel orally bioavailable prodrug of tebipenem, a carbapenem antimicrobial, that binds to penicillin-binding proteins, inhibiting the synthesis of the bacterial cell wall. This results in weakening of peptidoglycan, leading to lysis of bacterial cells. Tebipenem displays a broad spectrum of activity against anaerobic, gram-positive, and gram-negative pathogens, including extended-spectrum β-lactamase producing Enterobacterales. In a large phase 3 clinical trial (ADAPT-PO), oral tebipenem pivoxil hydrobromide 600 mg every 8 h was shown to be non-inferior to intravenous ertapenem 1 g every 24 h. Overall response at test of cure was 58.8% [264/449] in the tebipenem pivoxil hydrobromide group compared to 61.6% [258/419] in the ertapenem group for the treatment of complicated urinary tract infections, including acute pyelonephritis. At the test of cure, clinical cure rates were 93.1% and 93.6% and microbiological eradication was 59.5% and 63.5% with tebipenem pivoxil hydrobromide and ertapenem, respectively. The most common adverse reactions associated with tebipenem pivoxil hydrobromide are diarrhea, headache, and nausea. As with other carbapenems, tebipenem pivoxil hydrobromide is expected to have the potential to decrease the seizure threshold and will likely require renal dosage adjustment for patients with altered renal function due to high renal clearance. If approved in the United States, tebipenem pivoxil hydrobromide can serve as a potential oral antimicrobial option to decrease hospital length of stay and prevent hospital admissions due to resistant pathogens.

Oral Antibiotics in Clinical Development for Community-Acquired Urinary Tract Infections

The treatment of urinary tract infections (UTIs) has been complicated by the emergence of multidrug-resistant, β-lactamase-expressing pathogens. As a result of the limited treatment options, patients often require hospitalization and intravenous therapy. In essence, a strong unmet need for oral antibiotics, active against extended-spectrum β-lactamase (ESBL) uropathogens has emerged. Oral carbapenems (tebipenem and sulopenem) and oral cephalosporin/β-lactamase inhibitor combinations are in various stages of clinical development for the treatment of uncomplicated and complicated UTI. Tebipenem, if approved, will be the first oral treatment for complicated UTI while sulopenem will be for uncomplicated UTI. The β-lactamase inhibitors ETX0282, VNRX7145, ARX1796, and QPX7728 are combined with cefpodoxime proxetil or ceftibuten that achieve favorable exposures in urine compared to other uropathogen-active oral cephalosporins. The combination ceftibuten-QPX7728 has potential broad-spectrum coverage against carbapenemase producers including metallo β-lactamase producers. Other novel combinations, namely cefpodoxime/ETX0282, ceftibuten/VNRX-7145, and ceftibuten/ARX1796, have also demonstrated excellent activity against Klebsiella pneumoniae carbapanemase (KPC) and OXA-48-like producers. All these agents, upon their arrival for commercial use, would strengthen the outpatient therapy.

Pharmacokinetics, Urinary Excretion, and Pharmaco-Metabolomic Study of Tebipenem Pivoxil Granules After Single Escalating Oral Dose in Healthy Chinese Volunteers

Tebipenem pivoxil (TBPM-PI), an oral carbapenem antibiotic, has shown special advantages in pediatric infections and was in urgent need in China. Although pharmacokinetics, urinary excretion, and metabolite information of its active form tebipenem (TBPM) has been reported, ethnic differences may exist among the Chinese and Japanese population. By now, no systematic pharmacokinetics, urinary excretion, metabolites, or safety information has been revealed to the Chinese population. The purpose of the present work was to investigate abovementioned information of TBPM-PI granules after oral single ascending doses of 100, 200, and 400 mg in Chinese volunteers. Based on the pharmacokinetic study, the urine pharmaco-metabolomic analysis was conducted to reveal metabolomic interruptions and metabolite information. The study design was a single-center, open-label, randomized, single-dose pharmacokinetic study of 36 healthy volunteers (with half of them being male and the other half female). Time to maximum concentration (T max) was reached at 0.50, 0.50, or 0.67 h for 100, 200, or 400 mg, respectively. The linear pharmacokinetic characteristic of maximum plasma concentration (C max) was detected over 100-200 mg. The area under the concentration time curve (AUC) was proportional to the dose in the range of 100-400 mg. The maximum urinary excretion rate was detected at 0-1 or 1-2 h for dose of 100 or 200-400 mg. Cumulative amount of TBPM excreted in urine by 24 h accounted up to 90, 95, and 80% of dose administered for three groups, respectively. The pharmaco-metabolomic analysis revealed urine metabolic trajectory of deviation at 0-1 or 1-2 h and gradually regressing back to the pre-dose group at the following time periods. Urine metabolites from M1 to M4 were identified, indicating ethnic difference in metabolites among the Chinese or Japanese population. The current work proved safety and tolerance of single-dose administration of oral TBPM-PI in Chinese healthy volunteers over doses of 100-400 mg. All these results provide pharmacokinetics, urine excretion, urine metabolomics, urine metabolites, and safety information in healthy Chinese volunteers after oral single ascending doses of TBPM-PI, benefitting further development and clinical utilities.

Randomized, Double-Blind, Placebo- and Positive-Controlled Crossover Study of the Effects of Tebipenem Pivoxil Hydrobromide on QT/QTc Intervals in Healthy Subjects

Tebipenem pivoxil hydrobromide (TBP-PI-HBr) is an orally available prodrug of tebipenem (TBP), a carbapenem with in vitro activity against multidrug-resistant Gram-negative pathogens. This study evaluated the effects of single therapeutic and supratherapeutic doses of TBP-PI-HBr on the heart rate-corrected QT interval (QTc) by assessing the concentration-QT interval relationship using exposure-response modeling. This was a randomized, double-blind, placebo- and active-controlled, single-dose, four-way crossover study. Subjects received single oral doses of TBP-PI-HBr at 600 and 1,200 mg, placebo, and positive control (moxifloxacin at 400 mg). Cardiodynamic electrocardiograms (ECGs) and blood samples were collected in each period. Twenty-four subjects were enrolled. TBP-PI-HBr had no clinically significant adverse effects on heart rate or ECG parameters. The model-predicted slope suggests that the baseline-corrected difference in heart rate from placebo was not importantly affected by plasma TBP concentrations, supporting the use of the QT interval corrected by Fridericia's method as an appropriate correction. The model-predicted difference in QTc at the mean maximum concentration (Cmax) for TBP had negative predicted values for each dose, and no QTc prolongation was detected following TBP-PI-HBr at 600 mg or 1,200 mg. Assay sensitivity was established with moxifloxacin at 400 mg. Exposure to TBP increased in a dose-dependent manner with 600- and 1,200-mg doses. The TBP area under the concentration-time curve from time zero to infinity and Cmax with the 1,200-mg dose were 1.8- and 1.3-fold greater, respectively, than those with the 600-mg dose. TBP-PI-HBr was generally safe and well tolerated, with no effect in QT interval prolongation.

Resistance among urinary tract pathogens collected in Europe during 2018

OBJECTIVES

Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis are urinary tract infection (UTI) pathogens and extended spectrum β-lactamase (ESBL)-producing pathogens exhibit co-resistance to oral fluoroquinolones (FQ) and trimethoprim-sulphamethoxazole (TMP-SMX). This study assessed the prevalence of ESBL phenotypes and co-resistance to FQ and TMP-SMX.

METHODS

In total, 766 E. coli, 260 K. pneumoniae and 104 P. mirabilis from UTIs in 18 countries were evaluated for susceptibility in the SENTRY surveillance programme, and results interpreted using EUCAST criteria.

RESULTS

E. coli, K. pneumoniae and P. mirabilis accounted for 57.1%, 11.3% and 7.8%, respectively, of the isolates. Among E. coli, resistance to levofloxacin and TMP-SMX ranged from 21.8% to 32.7% for all isolates increasing to 66.5-67.0% among those with a ESBL phenotype (17.9% of all UTI E. coli from Europe were ESBL phenotypes). In contrast, all E. coli were susceptible to meropenem. For K. pneumoniae, resistance rates for levofloxacin and TMP-SMX were 32.2-40.0% increasing to 69.1-78.6% for ESBL phenotypes. Meropenem was the most active agent, with 7.7% resistance. Among P. mirabilis resistance to levofloxacin and TMP-SMX was 26-38.5% and increased to 100% for ESBL phenotypes. No meropenem-resistant P. mirabilis were reported.

CONCLUSIONS

High co-resistance rates were observed for oral antibiotics among ESBL phenotypes raising concerns regarding empiric use of FQ and TMP-SMX for treating resistant UTIs outside of the hospital. In contrast, intravenous carbapenems retain activity against resistant UTI pathogens. New oral options with the spectrum of the carbapenems would address an unmet need for managing resistant UTIs.