Pharmacokinetics and tolerability of lefamulin following intravenous and oral dosing

Safety and Pharmacokinetics Following Oral or Intravenous Lefamulin in Adults With Cystic Fibrosis

PURPOSE

Methicillin-resistant Staphylococcus aureus infections are increasing in prevalence in patients with cystic fibrosis (CF) and are associated with worsening lung function and increased mortality. Lefamulin is a pleuromutilin antimicrobial approved to treat community-acquired bacterial pneumonia based on potent in vitro activity and clinical efficacy. This Phase I, open-label, randomized crossover study assessed the safety and pharmacokinetic profile of oral and intravenous (IV) lefamulin in adults with CF.

METHODS

The study comprised 2 dosing periods in which adults with CF (N = 13) received a single dose of lefamulin via a 150-mg IV infusion or 600-mg immediate-release orally administered tablet, separated by a 4- to 7-day washout period. Pharmacokinetic and safety parameters were assessed after lefamulin treatment.

FINDINGS

Single doses of lefamulin administered via oral tablet or IV infusion resulted in comparable drug exposure, and sputum analysis suggested rapid penetration of lefamulin into the lung. Comparison of the present results with those obtained from prior single-dose studies of healthy volunteers indicate no meaningful difference in the pharmacokinetic properties of lefamulin in patients with CF. Treatment-emergent adverse events were consistent with previous reports, and the majority were mild in severity.

IMPLICATIONS

These results show similar lefamulin pharmacokinetic and safety profiles between patients with CF and healthy volunteers receiving the same oral and IV doses, suggesting no need for lefamulin dose adjustment in patients with CF and indicating the potential of lefamulin as therapy for lung infections in patients with CF.

CLINICALTRIALS

gov identifier: NCT05225805.

Design, synthesis, and evaluation of novel pleuromutilin aryl acrylate derivatives as promising broad-spectrum antibiotics especially for combatting multi-drug resistant gram-negative bacteria

The emergence of drug-resistant strains presents a grave challenge for traditional antibiotics, underscoring the exigency of exploring novel antibacterial drugs. To address this, the present study endeavors to design and synthesize a collection of pleuromutilin aromatic acrylate derivatives, guided by combination principles. The antibacterial activity and structure-activity relationship of these derivatives were evaluated, and most of the derivatives displayed moderate to excellent antibacterial activity against both Gram-positive bacteria and Gram-negative bacteria. Among these derivatives, 5g exhibited the strongest antibacterial activity, with MIC (minimum inhibitory concentration) values ranging from 1-32 μg/mL, and a MIC value against clinically isolated drug-resistant strains of 4-64 μg/mL. Additionally, 5g exhibited negligible cytotoxicity, superior anti-mycoplasma activity, and a greater propensity to perturb bacterial cell membranes. Notably, the administration of 5g resulted in an increased survival rate of MRSA (Methicillin-resistant Staphylococcus aureus)-infected mice, with an ED50 (median effective dose) value of 9.04 mg/kg. These results indicated the potential of 5g to be further developed as an antibacterial drug for the clinical treatment of drug-resistant bacterial infections.

Pharmacokinetic, Pharmacokinetic/Pharmacodynamic, and Safety Investigations of Lefamulin in Healthy Chinese Subjects

This study aimed to explore the pharmacokinetics (PK) and safety of oral (PO) and intravenous (IV) lefamulin in healthy Chinese subjects and to evaluate the efficacy of the intravenous administration regimen using pharmacokinetic/pharmacodynamic (PK/PD) analysis. This study was a randomized, open-label, single- and multiple-dose, intravenous and oral administration study. PK parameters were calculated, and the probability of target attainment (PTA) and the cumulative fraction of response (CFR) after IV administration of lefamulin 150 mg 1 h q12 h were analyzed with Monte Carlo simulations. Lefamulin exhibited extensive distribution. The mean steady-state AUC0-24 h of 150 mg lefamulin IV and 600 mg lefamulin PO were 10.03 and 13.96 μg·h/mL, respectively. For Streptococcus pneumoniae and Staphylococcus aureus, based on the free-drug AUC over MIC ratio (fAUC/MIC) target of 1-log10 cfu reduction, the PK/PD breakpoints were 0.25 and 0.125 mg/L, respectively. The CFR was over 90% for both types of strains with 95% protein binding rate, suggesting that the regimen was microbiologically effective. Lefamulin was safe and well-tolerated. The PK of lefamulin in healthy Chinese subjects were consistent with that in foreign countries. Lefamulin demonstrated the microbiological effectiveness against Streptococcus pneumoniae and Staphylococcus aureus.

Antibiotics with novel mode of action as new weapons to fight antimicrobial resistance

Antimicrobial resistance (AMR) is a major public health issue, causing 5 million deaths per year. Without any action plan, AMR will be in a near future the leading cause of death ahead of cancer. AMR comes from the ability of bacteria to rapidly develop and share resistance mechanisms towards current antibiotics, rendering them less effective. To circumvent this issue and avoid the phenomenon of cross-resistance, new antibiotics acting on novel targets or with new modes of action are required. Today, the pipeline of potential new treatments with these characteristics includes promising compounds such as gepotidacin, zoliflodacin, ibezapolstat, MGB-BP-3, CRS-3123, afabicin and TXA-709, which are currently in clinical trials, and lefamulin, which has been recently approved by FDA and EMA. In this review, we report the chemical synthesis, mode of action, structure-activity relationships, in vitro and in vivo activities as well as clinical data of these eight small molecules listed above.

Lefamulin

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Pharmacodynamic evaluation of lefamulin in the treatment of gonorrhea using a hollow fiber infection model simulating Neisseria gonorrhoeae infections

The emergence and spread of antimicrobial resistance in Neisseria gonorrhoeae is seriously threatening the treatment and control of gonorrhea globally. Novel treatment options are essential, coupled with appropriate methods to pharmacodynamically examine the efficacy and resistance emergence of these novel drugs. Herein, we used our dynamic in vitro hollow fiber infection model (HFIM) to evaluate protein-unbound lefamulin, a semisynthetic pleuromutilin, against N. gonorrhoeae. Dose-range and dose-fractionation experiments with N. gonorrhoeae reference strains: WHO F (susceptible to all relevant antimicrobials), WHO X (extensively drug-resistant, including ceftriaxone resistance), and WHO V (high-level azithromycin resistant, and highest gonococcal MIC of lefamulin (2 mg/l) reported), were performed to examine lefamulin gonococcal killing and resistance development during treatment. The dose-range experiments, simulating a single oral dose of lefamulin based on human plasma concentrations, indicated that ≥1.2 g, ≥2.8 g, and ≥9.6 g of lefamulin were required to eradicate WHO F, X, and V, respectively. Dose-fractionation experiments, based on human lefamulin plasma concentrations, showed that WHO X was eradicated with ≥2.8 g per day when administered as q12 h (1.4 g twice a day) and with ≥3.6 g per day when administered as q8 h (1.2 g thrice a day), both for 7 days. However, when simulating the treatment with 5-10 times higher concentrations of free lefamulin in relevant gonorrhea tissues (based on urogenital tissues in a rat model), 600 mg every 12 h for 5 days (approved oral treatment for community-acquired bacterial pneumonia) eradicated all strains, and no lefamulin resistance emerged in the successful treatment arms. In many arms failing single or multiple dose treatments for WHO X, lefamulin-resistant mutants (MIC = 2 mg/l), containing an A132V amino acid substitution in ribosomal protein L3, were selected. Nevertheless, these lefamulin-resistant mutants demonstrated an impaired biofitness. In conclusion, a clinical study is warranted to elucidate the clinical potential of lefamulin as a treatment option for uncomplicated gonorrhea (as well as several other bacterial STIs).

Design, synthesis, antibacterial activity evaluation and molecular docking study of pleuromutilin derivatives bearing amide side chains

A seize of pleuromutilin derivatives containing amide side chains were designed and synthesized as potential antibiotics against Methicillin-resistant Staphylococcus aureus (MRSA). Among all target compounds (compounds 11-30), compound 25 was found to have the strongest antibacterial activity against MRSA (minimum inhibitory concentration = 0.5 μg/ml). The result of the time-kill curves indicated that compound 25 could repress the growth of MRSA in vitro obviously (-3.72 log10 CFU/ml reduction). Furthermore, molecular docking studies demonstrated that compound 25 was localized in the binding pocket of 50S ribosomal subunit (ΔGb = -8.99 kcal/mol). Besides, compound 25 displayed low cytotoxicity to RAW 264.7 cells. The results suggested that compound 25 might be further developed into a novel antimicrobial agent against MRSA.

Clinical use of lefamulin: A first-in-class semisynthetic pleuromutilin antibiotic

Lefamulin is a novel antibiotic agent within the pleuromutilin derivative class approved for the treatment of community-acquired bacterial pneumonia (CABP) by the United States Food and Drug Administration and the European Commission in 2019 and 2020, respectively. The objective of this article is to provide a summary of clinically relevant data underlying lefamulin and to provide recommendations for its place in therapy. In vitro data establish lefamulin's activity against a number of Gram-positive, Gram-negative and atypical organisms relevant in the treatment of CABP, including Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Legionella pneumophila, Mycoplasma pneumoniae and Chlamydophila pneumoniae. Two phase-3 studies, the Lefamulin Evaluation Against Pneumonia trials, established non-inferiority of lefamulin against moxifloxacin in the treatment of CABP, including the sequential transition from intravenous to oral therapy and across a broad set of patient demographics and severities. Pooled and post hoc analyses have confirmed these effects for a variety of subgroups and secondary endpoints. Real-world study data post-approval have largely not yet emerged for lefamulin, and there is a need for further investigation into safety/efficacy for off-label indications such as acute bacterial skin and skin structure infections and sexually transmitted infections. Further data regarding tolerability, particularly with long-term use, as well as the emergence of resistance over time, are still undefined.

Retapamulin: Current Status and Future Perspectives

: Retapamulin is one of the antibiotics recently developed semi-synthetically to inhibit protein synthesis in a specific manner different from other antibiotics. This pleuromutilin derivative shows magnificent anti-bacterial activity in Gram-positive pathogens, especially Staphylococcus aureus and Streptococcus pyogenes, and now it is available in ointment formulations (1%) for clinical use with negligible side effects. Despite the low potential for resistance development, antimicrobial susceptibility rates are significantly high. This is especially important when the prevalence of mupirocin-resistant strains is increasing, and the need for new alternatives is urgent. Unfortunately, due to its oxidation by cytochrome p450, this drug cannot be used systemically. However, another pleuromutilin derivative with systemic use, lefamulin, was approved in August 2019 by the US Food and Drug Administration. In addition to pharmacokinetic features, financial issues are also barriers to consider in the progress of new antimicrobials. In this review, we attempt to take a brief look at the derivatives usable in humans and explore their structures, action mode, metabolism, possible ways of resistance, resistance rates, and their clinical use to explain and highlight the valuable points of these antibiotics.

Pooled Microbiological Findings and Efficacy Outcomes by Pathogen in Adults With Community-Acquired Bacterial Pneumonia from the Lefamulin Evaluation Against Pneumonia (LEAP) 1 and LEAP 2 Phase 3 Trials of Lefamulin Versus Moxifloxacin

BACKGROUND

Lefamulin, a pleuromutilin antibiotic approved for community-acquired bacterial pneumonia (CABP), was evaluated for microbiological efficacy in a prespecified pooled analysis of LEAP 1 and 2 phase 3 clinical trial data in patients with CABP.

METHODS

In LEAP 1, adults (Pneumonia Outcomes Research Team [PORT] risk class III‒V) received intravenous (IV) lefamulin 150 mg every 12 hours (q12h; 5‒7 days) or moxifloxacin 400 mg every 24 hours (q24h; 7 days), with optional IV-to-oral switch. In LEAP 2, adults (PORT II‒IV) received oral lefamulin 600 mg q12h (5 days) or moxifloxacin 400 mg q24h (7 days). Primary outcomes were early clinical response (ECR) 96±24 hours after treatment start and investigator assessment of clinical response (IACR) 5‒10 days after last dose. Secondary outcomes included ECR and IACR in patients with a baseline CABP pathogen (detected via culture, urinary antigen test, serology, and/or real-time PCR).

RESULTS

Baseline CABP pathogens were detected in 709/1289 patients (55.0% [microbiological intent-to-treat population]). The most frequently identified pathogens in this population were Streptococcus pneumoniae (61.9% of patients) and Haemophilus influenzae (29.9%); 25.1% had atypical pathogens and 33.1% had polymicrobial infections. Pathogens were identified most frequently by PCR from sputum, followed by culture from respiratory specimens. In patients with baseline CABP pathogens, ECR rates were 89.3% (lefamulin) and 93.0% (moxifloxacin); IACR success rates were 83.2% and 86.7%, respectively. Results were consistent across CABP pathogens, including drug-resistant isolates and polymicrobial infections.

CONCLUSIONS

Lefamulin is a valuable IV and oral monotherapy option for empiric and directed CABP treatment in adults.

Clinical Pharmacokinetics and Pharmacodynamics of Lefamulin

Lefamulin (Xenleta) has been approved by the US FDA for the treatment of community-acquired bacterial pneumonia (CABP). It may be taken intravenously or orally and has activity against a broad range of pulmonary pathogens, including Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Legionella pneumophila, and Chlamydophila pneumonia, as well as methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium. Lefamulin has an adverse effect profile that is similar to other antimicrobial agents commonly used to treat CABP. Despite these promising features, the use of lefamulin remains limited in clinical practice. However, given the rise of antibiotic-resistant organisms, this may soon change. This review examines what is known about the pharmacokinetics and pharmacodynamics of lefamulin and looks ahead to its potential applications in clinical practice, including the treatment of sexually transmitted infections such as multidrug-resistant Mycoplasma genitalium, as well as its role as a synergistic agent used in combination with other antimicrobials in the treatment of drug-resistant organisms.

Treatment of Community-Acquired Pneumonia: A Focus on Lefamulin

OBJECTIVE

The goal of this article is to review the clinical pharmacology, pharmacokinetics, efficacy, and safety of lemafulin.

DATA SOURCES

We performed a systematic literature review using the search terms of lefamulin and BC-3781 in the PubMed and EMBASE databases. We also cross-referenced the pertinent articles and searched ClinicalTrials.gov to identify ongoing and nonpublished studies.

STUDY SELECTION AND DATA EXTRACTION

Published data from 2005 to 2019 evaluating the clinical pharmacology, efficacy, and safety studies of lefamulin were analyzed.

DATA SYNTHESIS

In phase 3 clinical trials, two multicenter, randomized double-blinded studies-Lefamulin Evaluation Against Pneumonia 1 and 2 (LEAP 1 and 2)-compared the efficacy and safety of lemafulin with moxifloxacin in patients diagnosed with community-acquired bacterial pneumonia (CABP). Lemafulin given in doses of 600 mg orally or 150 mg intravenously were reported to have comparable efficacy to those of moxifloxacin with or without linezolid in patients with CABP. After the trial, the lefamulin group had an early clinical response (ECR) of 87.3% and the moxifloxacin group had an ECR of 90.2%. The difference of - 2.9% in the ECR was non-significant (CI - 8.5, 2.8).

RELEVANCE TO PATIENTS AND CLINICAL PRACTICE

Lemafulin exhibits a unique binding property; therefore, it possess a potentially lower predisposition for the development of bacterial resistance and cross-resistance to other antimicrobial classes. Lefamulin is active against gram-positive including methicillin-resistant strains and atypical organisms which are often implicated in CABP. Lefamulin may be a safe alternative for adult patients with CABP who may not be candidates for respiratory fluoroquinolones. Lefamulin demonstrates both bactericidal and bacteriostatic activity against gram-positive, fastidious gram-negatives, atypical pathogens, and some gram-negative anaerobes. It is bactericidal in vitro against Streptococcus pneumoniae, Haemophilus influenzae, and Mycoplasma pneumoniae (including macrolide-resistant strains) at concentrations of 0.06, 0.5, and 0.008 µg/ml respectively, and bacteriostatic against Staphylococcus aureus and Streptococcus pyogenes. The agent also demonstrates both time- and concentration-dependent killing against the pathogens S. pneumoniae and S. aureus. In vitro susceptibility testing demonstrated an MIC50/90 of 0.06/0.12 µg/ml against S. pneumoniae and S. aureus. The SENTRY Antimicrobial Surveillance Program found that at a concentration ≤ 1 µg/ml, lefamulin inhibited 100% S. pneumoniae isolates, 99.8% of S. aureus isolates, and 99.6% of methicillin-resistant S. aureus isolates. It was not affected by resistance to various antibiotic classes such as beta-lactams, fluoroquinolones, or macrolides.

Lefamulin: The First Systemic Pleuromutilin Antibiotic

OBJECTIVE

To review the pharmacology, microbiology, efficacy, and safety of lefamulin.

DATA SOURCES

A literature search was performed using PubMed and Google Scholar (2010 to end-April 2020) with the search terms BC-3781 and lefamulin. Other resources included abstracts presented at recent conferences, prescribing information, and the manufacturer's and Food and Drug Administration websites.

STUDY SELECTION AND DATA EXTRACTION

All relevant English-language articles of studies assessing the efficacy and safety of lefamulin were included.

DATA SYNTHESIS

Lefamulin is a pleuromutilin antibiotic with activity against Staphylococcus aureus, Streptococcus pneumoniae, and atypical bacteria. Lefamulin, given at the dose of 150 mg intravenously or 600 mg orally on an empty stomach every 12 hours for 5 to 7 days, was proven noninferior to moxifloxacin for the treatment of community-acquired bacterial pneumonia (CABP). Common adverse reactions include injection site reactions, hepatic enzyme elevation, gastrointestinal upset, hypokalemia, insomnia, and headache. Lefamulin is associated with QT prolongation, and concomitant use with CYP3A substrates that prolong the QT interval is contraindicated. Lefamulin may cause fetal harm.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Lefamulin is a novel antibiotic with a unique mechanism of action. It represents an alternative option to β-lactams and macrolides in the treatment of adults with CABP and an alternative option to amoxicillin and doxycycline in the outpatient setting given the rise in resistance to macrolides and safety concerns with fluoroquinolones. Nausea, vomiting, and diarrhea may limit the tolerability of the oral formulation.

CONCLUSIONS

Lefamulin is the first systemic pleuromutilin antibiotic that has proven safe and effective for adults with CABP.

Lefamulin: A Novel Oral and Intravenous Pleuromutilin for the Treatment of Community-Acquired Bacterial Pneumonia

Lefamulin is a novel oral and intravenous (IV) pleuromutilin developed as a twice-daily treatment for community-acquired bacterial pneumonia (CABP). It is a semi-synthetic pleuromutilin with a chemical structure that contains a tricyclic core of five-, six-, and eight-membered rings and a 2-(4-amino-2-hydroxycyclohexyl)sulfanylacetate side chain extending from C14 of the tricyclic core. Lefamulin inhibits bacterial protein synthesis by binding to the 50S bacterial ribosomal subunit in the peptidyl transferase center (PTC). The pleuromutilin tricyclic core binds to a pocket close to the A site, while the C14 side chain extends to the P site causing a tightening of the rotational movement in the binding pocket referred to as an induced-fit mechanism. Lefamulin displays broad-spectrum antibacterial activity against Gram-positive and Gram-negative aerobic and anaerobic bacteria as well as against atypical bacteria that commonly cause CABP. Pleuromutilin antibiotics exhibit low rates of resistance development and lack cross-resistance to other antimicrobial classes due to their unique mechanism of action. However, pleuromutilin activity is affected by mutations in 23S rRNA, 50S ribosomal subunit proteins rplC and rplD, ATP-binding cassette (ABC)-F transporter proteins such as vga(A), and the methyltransferase cfr. The pharmacokinetic properties of lefamulin include: volume of distribution (V_d) ranging from 82.9 to 202.8 L, total clearance (CL_T) of 19.5 to 21.4 L/h, and terminal elimination half-life (t_1/2) of 6.9-13.2 h; protein binding of lefamulin is high and non-linear. The oral bioavailability of lefamulin has been estimated as 24% in fasted subjects and 19% in fed subjects. A single oral dose of lefamulin 600 mg administered in fasted patients achieved a maximum plasma concentration (C_max) of 1.2-1.5 mg/L with a time of maximum concentration (T_max) ranging from 0.8 to 1.8 h, and an area under the plasma concentration-time curve from 0 to infinity (AUC_0-∞) of 8.5-8.8 mg h/L. The pharmacodynamic parameter predictive of lefamulin efficacy is the free plasma area under the concentration-time curve divided by the minimum inhibitory concentration (fAUC_24h/MIC). Lefamulin efficacy has been demonstrated using various animal models including neutropenic murine thigh infection, pneumonia, lung infection, and bacteremia. Lefamulin clinical safety and efficacy was investigated through a Phase II clinical trial of acute bacterial skin and skin structure infection (ABSSSI), as well as two Phase III clinical trials of CABP. The Phase III trials, LEAP 1 and LEAP 2 established non-inferiority of lefamulin to moxifloxacin in both oral and IV formulations in the treatment of CABP. The United States Food and Drug Administration (FDA), European Medicines Agency (EMA), and Health Canada have each approved lefamulin for the treatment of CABP. A Phase II clinical trial has been completed for the treatment of ABSSSI, while the pediatric program is in Phase I. The most common adverse effects of lefamulin include mild-to-moderate gastrointestinal-related events such as nausea and diarrhea. Lefamulin represents a safe and effective option for treating CABP in cases of antimicrobial resistance to first-line therapies, clinical failure, or intolerance/adverse effects to currently used agents. Clinical experience and ongoing clinical investigation will allow clinicians and antimicrobial stewardship programs to optimally use lefamulin in the treatment of CABP.

Clinical Utility of Lefamulin: If Not Now, When?

Purpose of Review

The looming threat of antimicrobial resistance requires robust stewardship and new developments in infectious diseases pharmacotherapy. This review discusses the pertinent spectrum and clinical data of lefamulin (Xenleta®), with a focus on potential real-world use.

Recent Findings

Lefamulin is a novel pleuromutilin antibiotic that obtained Food and Drug Administration labeling for community-acquired bacterial pneumonia (CABP) in 2019. Lefamulin is available in both intravenous and oral formulations, and it inhibits bacterial protein synthesis inhibition through interactive binding to unique sites of the peptidyl transferase center of the 50s bacterial ribosome subunit. Resistance, including cross-resistance with other antibiotics, is infrequent. Lefamulin demonstrates activity against most Gram-positive pathogens and other organisms commonly associated with CABP, i.e., Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Legionella pneumophila, and Chlamydophila pneumoniae. Lefamulin may also be an option for serious public health threats like methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecium, and multi-drug-resistant organisms associated with sexually transmitted infections, e.g., Neisseria gonorrhoeae, Mycoplasma genitalium. Lefamulin lacks activity against Pseudomonas aeruginosa, Acinetobacter baumannii, Enterobacterales, most anaerobes, and E. faecalis. In Phase III trials, lefamulin monotherapy was non-inferior to moxifloxacin with or without linezolid for CABP.

Summary

Lefamulin is a well-tolerated agent with a unique mechanism, availability in both IV and PO formulations, and it has been rigorously studied for safety and efficacy for CABP.

An overview of lefamulin for the treatment of community acquired bacterial pneumonia

INTRODUCTION

Lefamulin is a novel antibiotic that belongs to the pleuromutilin class with excellent activity against all microorganisms, including atypical pathogens, that cause community-acquired pneumonia (CAP).

AREAS COVERED

This article reviews the spectrum of activity, the main pharmacokinetic and pharmacodynamic characteristics of lefamulin as well as its clinical efficacy and safety in the treatment of CAP in adult patients.

EXPERT OPINION

The clinical efficacy of lefamulin in patients with non severe CAP has been demonstrated in 2 randomized clinical trials. Precisely one of the limitations of the phase 3 trials is that the proportion of severe CAP cases is very low. Its particular mechanism of action, affecting ribosomal protein synthesis, provides a low probability of cross-resistance to other commonly used antibiotics in CAP. These findings, together with the antimicrobial activity of lefamulin, its pharmacokinetic parameters and safety profile make it a good alternative for outpatient treatment of CAP. In patients hospitalized with CAP, lefamulin can be used as a potential oral step-down agent after an intravenous regimen with beta-lactams, or as a therapeutic alternative in patients with β-lactam allergies.

Antibacterial Activity of Lefamulin against Pathogens Most Commonly Causing Community-Acquired Bacterial Pneumonia: SENTRY Antimicrobial Surveillance Program (2015-2016)

Lefamulin, the first semisynthetic pleuromutilin antibacterial for intravenous and oral treatment of community-acquired bacterial pneumonia (CABP), and comparators were evaluated for in vitro activity against a global collection of pathogens commonly causing CABP (n = 8595) from the 2015 and 2016 SENTRY Antimicrobial Surveillance Program. Lefamulin was highly active against the pathogens Streptococcus pneumoniae, including multidrug-resistant and extensively drug-resistant strains (MIC50/90 for total and resistant subsets, 0.06/0.12 μg/ml; 100% inhibited at ≤1 μg/ml), Staphylococcus aureus, including methicillin-resistant Staphylococcus aureus (MRSA; both MIC50/90, 0.06/0.12 μg/ml; 99.8% and 99.6% inhibited at ≤1 μg/ml, respectively), Haemophilus influenzae (MIC50/90, 0.5/1 μg/ml; 93.8% inhibited at ≤1 μg/ml), and Moraxella catarrhalis (MIC50/90, 0.06/0.12 μg/ml; 100% inhibited at ≤0.25 μg/ml), and its activity was unaffected by resistance to other antibacterial classes.

Introduction: lefamulin and pharmacokinetic/pharmacodynamic rationale to support the dose selection of lefamulin

Lefamulin is the first semisynthetic pleuromutilin being developed for oral and intravenous administration. The drug selectively inhibits prokaryotic ribosomal protein synthesis by binding to the peptidyl transferase centre via four H-bonds and other interactions, resulting in an 'induced fit' that tightens the binding pocket around lefamulin. This unique mechanism of action has been associated with a low probability of cross-resistance to other antimicrobial classes commonly used to treat community-acquired bacterial pneumonia (CABP). This Supplement, entitled 'Pharmacokinetic and pharmacodynamic analyses and dose rationale for lefamulin, a novel pleuromutilin antibiotic, for the treatment of community-acquired bacterial pneumonia', is intended to be a valuable resource for both clinicians and researchers. It provides the essential pharmacokinetic and pharmacodynamic data on lefamulin that were used to support the optimal dose selection of lefamulin for the safe and effective treatment of CABP in adults.