Pharmacokinetics of tedizolid following oral administration: single and multiple dose, effect of food, and comparison of two solid forms of the prodrug

Deciphering linezolid-induced hematologic toxicity: Targeting TOP2A and TOP2B via its primary metabolite PNU142586

Linezolid, an oxazolidinone antibiotic, is widely used to treat multidrug-resistant tuberculosis and drug-resistant Gram-positive infections. However, prolonged use is associated with severe hematologic toxicity, the underlying mechanisms of which remain incompletely understood, particularly regarding the role of linezolid metabolites. Our clinical study indicates that elevated exposure to PNU142586, a primary metabolite of linezolid, is associated with an increased risk of linezolid-induced toxicity, even in the absence of renal impairment. To elucidate its mechanism, we identify DNA topoisomerase 2-α (TOP2A) and DNA topoisomerase 2-β (TOP2B) as primary targets of PNU142586 at molecular, cellular, and in vivo levels. PNU142586 disrupts replication and transcription by impeding DNA binding to TOP2A and TOP2B with a favorable conformation for cleavage and by inhibiting adenosine 5'-triphosphate hydrolysis, ultimately leading to antiproliferative and cytotoxic effects, including mitochondrial dysfunction. The present study thus provides mechanistic insight into linezolid-induced hematologic toxicity and offers a foundation for safer antibiotic development and improved clinical monitoring through biomarker identification.

Clinical efficacy and safety assessment of tedizolid using therapeutic drug monitoring

Thrombocytopenia derived from tedizolid (TZD) has been reported but less frequently than that from linezolid. Only a few reports have investigated the relationship between the efficacy and safety of TZD administration. This study aimed to measure TZD concentration and investigate the relationship between efficacy and safety. The study was conducted at the Aichi Medical University Hospital. All patients administered TZD were included; the serum trough concentration (Cmin) of TZD was measured using LM1010 high-performance liquid chromatography. Efficacy was assessed as clinical and microbiological efficacy. Clinical efficacy was defined as no recurrence and no need for additional treatment until 2 weeks after the end of TZD therapy. Microbiological efficacy was defined as the absence of bacteria during and after TZD therapy. Safety was assessed using thrombocytopenia. Thrombocytopenia was defined as a decrease in platelet count of ≥25 % compared with baseline levels and a minimum count of <10 × 104/μL. Seventeen patients were included. The Cmin in 16 patients was <0.5 μg/mL; one patient had a Cmin of 1.01 μg/mL complicated by hepatic cirrhosis. Clinical and microbiological efficacy was found in >80 % of the patients. Thrombocytopenia occurred in 14.3 % (2/14) of the patients. The Cmin in two patients with thrombocytopenia were 0.14 and 0.28 μg/mL, respectively. The serum concentration of TZD might increase in patients with hepatic cirrhosis; therapeutic drug monitoring may be required. Thrombocytopenia due to TZD could occur regardless of its serum concentration, necessitating monitoring for platelet count.

Pharmacokinetic/pharmacodynamic analysis of tedizolid phosphate against Staphylococcus aureus and Streptococcus pneumoniae in children, adolescents, and adults by Monte Carlo simulation

OBJECTIVE

The objective of this study was to investigate the cumulative fraction of response of various dosage regimens of tedizolid phosphate against Staphylococcus aureus and Streptococcus pneumoniae in children, adolescents, and adults.

METHODS

Monte Carlo simulations were performed using previously published pharmacokinetic parameters and pharmacodynamic data to evaluate the efficacy of the simulated dosage strategies in terms of area under the concentration-time curve/minimum inhibitory concentration targets of tedizolid.

RESULTS

According to the results of the Monte Carlo simulations, currently approved dosage regimens of tedizolid phosphate were effective in the treatment of acute bacterial skin and skin structure infections (ABSSSIs) caused by methicillin-susceptible S. aureus and methicillin-resistant S. aureus (MRSA) including vancomycin-intermediate, heterogeneous vancomycin-intermediate, and daptomycin-non-susceptible MRSA in adult and paediatric patients aged 12 y and older. High-dose regimens of tedizolid phosphate should be the preferred option to optimize efficacy against ABSSSIs caused by linezolid-resistant MRSA, particularly chloramphenicol-florfenicol resistance-mediated isolates. The dosage regimens of 3 and 4 mg/kg/d of tedizolid phosphate were appropriate to treat ABSSSIs caused by methicillin-susceptible S. aureus and MRSA in children aged 2-6 and 6-12 y, respectively. Approved dosage regimens of tedizolid phosphate for patients older than 12 y may be sufficient against S. pneumoniae pneumonia but insufficient for S. aureus pneumonia. For neutropenic patients, almost all the simulated regimens of tedizolid phosphate were ineffective against S. aureus and S. pneumoniae.

CONCLUSIONS

These pharmacokinetics/pharmacodynamics-based simulations rationalize and optimize the dosage regimens of tedizolid phosphate against S. aureus and S. pneumoniae in children, adolescents, and adults.

Tedizolid phosphate alleviates DSS-induced ulcerative colitis by inhibiting senescence of cell and colon tissue through activating AMPK signaling pathway

Ulcerative colitis (UC) is a subtype of inflammatory bowel disease. Previous studies have suggested a link between senescence process and the body's inflammatory reaction, indicating that senescence may exacerbate UC, yet the relation between UC and senescence remains unclear. Tedizolid Phosphate (TED), a novel oxazolidinone antimicrobial, is indicated in acute bacterial skin infections, its impact on senescence is not known. Our research revealed that the UC inducer dextran sulfate sodium (DSS) triggers senescence in both colon epithelial NCM460 cells and colon tissues, and TED that screened from a compound library demonstrated a strong anti-senescence effect on DSS treated NCM460 cells. As an anti-senescence medication identified in this research, TED efficiently alleviated UC and colonic senescence in mice caused by DSS. By proteomic analysis and experimental validation, we found that DSS significantly inhibits the AMPK signaling pathway, while TED counteracts senescence by restoring AMPK activity. This research verified that the development of UC is accompanied with colon tissue senescence, and TED, an anti-senescence medication, can effectively treat UC caused by DSS and alleviate colon senescence. Our work suggests anti-senescence strategy is an effective approach for UC treatment.

New Oxazolidinones for Tuberculosis: Are Novel Treatments on the Horizon?

Multidrug-resistant tuberculosis (MDR-TB) is a global health concern. Standard treatment involves the use of linezolid, a repurposed oxazolidinone. It is associated with severe adverse effects, including myelosuppression and mitochondrial toxicity. As such, it is imperative to identify novel alternatives that are better tolerated but equally or more effective. Therefore, this review aims to identify and explore the novel alternative oxazolidinones to potentially replace linezolid in the management of TB. The keywords tuberculosis and oxazolidinones were searched in PubMed to identify eligible compounds. The individual drug compounds were then searched with the term tuberculosis to identify the relevant in vitro, in vivo and clinical studies. The search identified sutezolid, tedizolid, delpazolid, eperezolid, radezolid, contezolid, posizolid and TBI-223, in addition to linezolid. An additional search resulted in 32 preclinical and 21 clinical studies. All novel oxazolidinones except posizolid and eperezolid resulted in positive preclinical outcomes. Sutezolid and delpazolid completed early phase 2 clinical studies with better safety and equal or superior efficacy. Linezolid is expected to continue as the mainstay therapy, with renewed interest in drug monitoring. Sutezolid, tedizolid, delpazolid and TBI-223 displayed promising preliminary results. Further clinical studies would be required to assess the safety profiles and optimize the dosing regimens.

A phase I study of the safety, tolerability, and pharmacokinetics of contezolid acefosamil after intravenous and oral administration in healthy Chinese subjects

Contezolid acefosamil (also known as MRX-4), a prodrug of contezolid, is under development for treatment of multidrug-resistant Gram-positive bacterial infections. A phase I single ascending dose (SAD) and multiple-dose placebo-controlled study was conducted to assess the safety, tolerability, and pharmacokinetics (PK) of contezolid acefosamil in healthy Chinese subjects following intravenous (IV) and oral administration. Adverse events (AEs) and PK parameters were assessed appropriately. All subjects (n = 70) completed the trial. Overall, 67 cases of treatment-emergent adverse events (TEAEs) were observed in 49.1% (27 of 55) of the subjects receiving contezolid acefosamil. All TEAEs were mild in severity. No serious AEs or deaths were reported. After IV SAD (500-2,000 mg), the corresponding C max of the active drug contezolid increased from 1.95 ± 0.57 to 15.61 ± 4.88 mg/L, AUC0-inf from 40.25 ± 10.12 to 129.41 ± 38.30 h·mg/L, median T max from 2.00 to 2.75 h, and mean t 1/2 from 13.33 to 16.74 h. Plasma contezolid reached steady state on day 6 after multiple IV doses, with an accumulation ratio of 2.20-2.96. Oral SAD of 500 and 1,500 mg resulted in contezolid C max of 8.66 ± 2.60 and 37.10 ± 8.66 mg/L, AUC0-inf of 30.44 ± 7.33 and 162.36 ± 47.08 h·mg/L, and median T max of 2.50 and 2.98 h. Contezolid reached steady state on day 5 after multiple oral doses of 1,500 mg without significant accumulation. Contezolid C max and AUC0-inf increased with the dose of contezolid acefosamil. The good safety and PK profiles in this SAD and multiple-dose study can support further clinical development of contezolid acefosamil.

The Role of Five-Membered Heterocycles in the Molecular Structure of Antibacterial Drugs Used in Therapy

Five-membered heterocycles are essential structural components in various antibacterial drugs; the physicochemical properties of a five-membered heterocycle can play a crucial role in determining the biological activity of an antibacterial drug. These properties can affect the drug's activity spectrum, potency, and pharmacokinetic and toxicological properties. Using scientific databases, we identified and discussed the antibacterials used in therapy, containing five-membered heterocycles in their molecular structure. The identified five-membered heterocycles used in antibacterial design contain one to four heteroatoms (nitrogen, oxygen, and sulfur). Antibacterials containing five-membered heterocycles were discussed, highlighting the biological properties imprinted by the targeted heterocycle. In some antibacterials, heterocycles with five atoms are pharmacophores responsible for their specific antibacterial activity. As pharmacophores, these heterocycles help design new medicinal molecules, improving their potency and selectivity and comprehending the structure-activity relationship of antibiotics. Unfortunately, particular heterocycles can also affect the drug's potential toxicity. The review extensively presents the most successful five-atom heterocycles used to design antibacterial essential medicines. Understanding and optimizing the intrinsic characteristics of a five-membered heterocycle can help the development of antibacterial drugs with improved activity, pharmacokinetic profile, and safety.

Minocycline intra-bacterial pharmacokinetic hysteresis as a basis for pharmacologic memory and a backbone for once-a-week pan-tuberculosis therapy

Background: There is need for shorter duration regimens for the treatment of tuberculosis, that can treat patients regardless of multidrug resistance status (pan-tuberculosis).

Methods: We combined minocycline with tedizolid, moxifloxacin, and rifampin, in the hollow fiber system model of tuberculosis and mimicked each drugs’ intrapulmonary pharmacokinetics for 28 days. Minocycline-tedizolid was administered either as a once-a-week or a daily regimen. In order to explore a possible explanation for effectiveness of the once-a-week regimen, we measured systemic and intra-bacterial minocycline pharmacokinetics. Standard daily therapy (rifampin, isoniazid, pyrazinamide) was the comparator. We then calculated γ_f or kill slopes for each regimen and ranked the regimens by time-to-extinction predicted in patients.

Results: The steepest γ_f and shortest time-to-extinction of entire bacterial population was with daily minocycline-rifampin combination. There was no difference in γ_f between the minocycline-tedizolid once-a-week versus the daily therapy (p = 0.85). Standard therapy was predicted to cure 88% of patients, while minocycline-rifampin would cure 98% of patients. Minocycline concentrations fell below minimum inhibitory concentration after 2 days of once-weekly dosing schedule. The shape of minocycline intra-bacterial concentration-time curve differed from the extracellular pharmacokinetic system and lagged by several days, consistent with system hysteresis. Hysteresis explained the persistent microbial killing after hollow fiber system model of tuberculosis concentrations dropped below the minimum inhibitory concentration.

Conclusion: Minocycline could form a backbone of a shorter duration once-a-week pan-tuberculosis regimen. We propose a new concept of post-antibiotic microbial killing, distinct from post-antibiotic effect. We propose system hysteresis as the basis for the novel concept of pharmacologic memory, which allows intermittent dosing.

Long-term use of tedizolid for pulmonary nocardiosis

Nocardiosis usually occurs in immunocompromised patients and causes infections in various organs, including the lungs, skin, and organs of the central nervous system. Herein, we report the case of a patient with minimal change nephrotic syndrome who had been on immunosuppressive drugs and developed pulmonary nocardiosis due to Nocardia nova complex and Pneumocystis pneumonia. For pulmonary nocardiosis, trimethoprim-sulfamethoxazole, linezolid, and clarithromycin were initiated sequentially, but were subsequently discontinued due to side effects; the treatment was completed with tedizolid. Tedizolid was used safely for 200 out of 286 days of antibiotic treatment, and clinical improvement was observed. Tedizolid is a bacteriostatic oxazolidine antibiotic that inhibits bacterial protein synthesis, the same mechanism as its predecessor, linezolid. Tedizolid is thought to cause less frequent myelosuppression than linezolid, at least for short-term use. In the future, tedizolid may be a promising alternative to linezolid in cases of nocardiosis that usually require long-term treatment.

Pharmacokinetics and Pharmacodynamics of Tedizolid

Tedizolid is an oxazolidinone antibiotic with high potency against Gram-positive bacteria and currently prescribed in bacterial skin and skin-structure infections. The aim of the review was to summarize and critically review the key pharmacokinetic and pharmacodynamic aspects of tedizolid. Tedizolid displays linear pharmacokinetics with good tissue penetration. In in vitro susceptibility studies, tedizolid exhibits activity against the majority of Gram-positive bacteria (minimal inhibitory concentration [MIC] of ≤ 0.5 mg/L), is four-fold more potent than linezolid, and has the potential to treat pathogens being less susceptible to linezolid. Area under the unbound concentration-time curve (fAUC) related to MIC (fAUC/MIC) was best correlated with efficacy. In neutropenic mice, fAUC/MIC of ~ 50 and ~ 20 induced bacteriostasis in thigh and pulmonary infection models, respectively, at 24 h. The presence of granulocytes augmented its antibacterial effect. Hence, tedizolid is currently not recommended for immunocompromised patients. Clinical investigations with daily doses of 200 mg for 6 days showed non-inferiority to twice-daily dosing of linezolid 600 mg for 10 days in patients with acute bacterial skin and skin-structure infections. In addition to its use in skin and skin-structure infections, the high pulmonary penetration makes it an attractive option for respiratory infections including Mycobacterium tuberculosis. Resistance against tedizolid is rare yet effective antimicrobial surveillance and defining pharmacokinetic/pharmacodynamic targets for resistance suppression are needed to guide dosing strategies to suppress resistance development.

Aminopenicillins for treatment of ampicillin-resistant enterococcal urinary tract infections

DISCLAIMER

In an effort to expedite the publication of articles related to the COVID-19 pandemic, AJHP is posting these manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

The purpose of this review is to describe the theory behind and data supporting use of aminopenicillins in the treatment of ampicillin-resistant enterococcal urinary tract infections.

SUMMARY

Aminopenicillin concentrations in the urine may be high enough to achieve bacterial eradication and clinical cure for infections affecting the lower genitourinary tract, even in the context of in vitro resistance based on established susceptibility breakpoints. A literature search was conducted to identify original research articles describing the use of aminopenicillins in the treatment of urinary tract infections caused by ampicillin-resistant Enterococcus species. Three published retrospective cohort studies were identified, all of which reported that aminopenicillins had similar rates of clinical cure as other antibiotic classes prescribed for the treatment of enterococcal urinary tract infections.

CONCLUSION

Both pharmacokinetic/pharmacodynamic principles and limited retrospective clinical data support the use of aminopenicillins in the treatment of lower urinary tract infections caused by Enterococcus species, even when the isolates have a minimum inhibitory concentration that exceeds the susceptibility breakpoint.

Importance and Reality of TDM for Antibiotics Not Covered by Insurance in Japan

Under the Japanese health insurance system, medicines undergoing therapeutic drug monitoring (TDM) can be billed for medical fees if they meet the specified requirements. In Japan, TDM of vancomycin, teicoplanin, aminoglycosides, and voriconazole, which are used for the treatment of infectious diseases, is common practice. This means the levels of antibiotics are measured in-house using chromatography or other methods. In some facilities, the blood and/or tissue concentrations of other non-TDM drugs are measured by HPLC and are applied to treatment, which is necessary for personalized medicine. This review describes personalized medicine based on the use of chromatography as a result of the current situation in Japan.

New Antibiotics for Hospital-Acquired Pneumonia and Ventilator-Associated Pneumonia

Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) represent one of the most common hospital-acquired infections, carrying a significant morbidity and risk of mortality. Increasing antibiotic resistance among the common bacterial pathogens associated with HAP and VAP, especially Enterobacterales and nonfermenting gram-negative bacteria, has made the choice of empiric treatment of these infections increasingly challenging. Moreover, failure of initial empiric therapy to cover the causative agents associated with HAP and VAP has been associated with worse clinical outcomes. This review provides an overview of antibiotics newly approved or in development for the treatment of HAP and VAP. The approved antibiotics include ceftobiprole, ceftolozane-tazobactam, ceftazidime-avibactam, meropenem-vaborbactam, imipenem-relebactam, and cefiderocol. Their major advantages include their high activity against multidrug-resistant gram-negative pathogens.

Development of a simple method for measuring tedizolid concentration in human serum using HPLC with a fluorescent detector

The objective of the present study was to develop a method to measure tedizolid (TZD) concentration for studying target concentration intervention, pharmacokinetics, and pharmacodynamics of TZD. We established a high-performance liquid chromatography-fluorescence detector assay to measure the TZD concentration in serum for clinical application. Chromatographic separation was carried out on a 5 μm octadecyl silane hypersil column 150 mm × 4.6 mm. The mobile phase consisted of 0.1 M phosphoric acid and methanol (60:40, pH 7.0). Detection was performed at 300 nm and 340 nm for the excitation and emission wavelengths, respectively. The average retention times of TZD and the internal standard were 12.9 and 8.8 min, respectively. High linearity was exhibited over a concentration range of 0.025 to 10.0 μg/mL for TZD (R2 > 0.999). The intra- and inter-assay accuracies of TZD were 99.2% to 107.0% and 99.2% to 107.7%, respectively. The lower limit of quantitation and the lower limit of detection for TZD measurement were 0.025 and 0.01 μg/mL, respectively. The extraction recoveries of TZD were 100.4% to 114.1%.The high-performance liquid chromatography method developed in this study could separate the analytes with a single eluent (isocratic system), within a total run time of 15 min. Both TZD and IS were well separated, without interference from the peaks. Sharp peaks were observed in the chromatograms; problems such as double peaks, shoulder peaks, and broadened peaks were not observed. The proposed method showed acceptable analytical performance and could be used to evaluate serum TZD concentrations in patients.

Current Landscape and Future Perspective of Oxazolidinone Scaffolds Containing Antibacterial Drugs

The widespread use of antibiotics has made the problem of bacterial resistance increasingly serious, and the study of new drug-resistant bacteria has become the main direction of antibacterial drug research. Among antibiotics, the fully synthetic oxazolidinone antibacterial drugs linezolid and tedizolid have been successfully marketed and have achieved good clinical treatment effects. Oxazolidinone antibacterial drugs have good pharmacokinetic and pharmacodynamic characteristics and unique antibacterial mechanisms, and resistant bacteria are sensitive to them. This Perspective focuses on reviewing oxazolidinones based on the structural modification of linezolid and new potential oxazolidinone drugs in the past 10 years, mainly describing their structure, antibacterial activity, safety, druggability, and so on, and discusses their structure-activity relationships, providing insight into the reasonable design of safer and more potent oxazolidinone antibacterial drugs.

A review of current and promising nontuberculous mycobacteria antibiotics

Nontuberculous mycobacteria infections are a growing concern, and their incidence has been increasing worldwide in recent years. Current treatments are not necessarily useful because many were initially designed to work against other bacteria, such as Mycobacterium tuberculosis. In addition, inadequate treatment means that resistant strains are increasingly appearing, particularly for Mycobacterium abscessus, one of the most virulent nontuberculous mycobacteria. There is an urgent need to develop new antibiotics specifically directed against these nontuberculous mycobacteria. To help in this fight against the emergence of these pathogens, this review describes the most promising heterocyclic antibiotics under development, with particular attention paid to their structure-activity relationships.

New-Generation Antibiotics for Treatment of Gram-Positive Infections: A Review with Focus on Endocarditis and Osteomyelitis

Infective endocarditis, osteomyelitis, and osteosynthesis-associated infections are mostly caused by Gram-positive bacteria. They are often difficult to treat and are associated with a poor prognosis. In the past 20 years, nine antibiotic drugs with predominant activity against Gram-positive bacteria have been introduced and approved by the Food and Drug Administration or the European Medicines Agency: ceftaroline, daptomycin, telavancin, dalbavancin, oritavancin, linezolid, tedizolid, delafloxacin, and omadacycline. This narrative review aims to provide an overview on these antibiotics with a special focus on their use in infective endocarditis, osteomyelitis, and osteosynthesis-associated infections. Although some of these approved antibiotics are promising, they should not be used as first- or second-line therapy, awaiting more clinical data.

Tedizolid is a promising antimicrobial option for the treatment of Staphylococcus aureus infections in cystic fibrosis patients

BACKGROUND

Tedizolid is a protein synthesis inhibitor in clinical use for the treatment of Gram-positive infections. Pulmonary MRSA infections are a growing problem in patients with cystic fibrosis (CF) and the efficacy of tedizolid-based therapy in CF pulmonary infections is unknown.

OBJECTIVES

To evaluate the in vitro and in vivo activity of tedizolid and predict the likelihood of tedizolid resistance selection in CF-background Staphylococcus aureus strains.

METHODS

A collection of 330 S. aureus strains (from adult and paediatric patients), either of normal or small colony variant (SCV) phenotypes, gathered at three CF centres in the USA was used. Tedizolid activity was assessed by broth microdilution, Etest and time-kill analysis. In vivo tedizolid efficacy was tested in a murine pneumonia model. Tedizolid in vitro mutants were obtained by 40 days of exposure and progressive passages. Whole genome sequencing of clinical S. aureus strains with reduced susceptibility to tedizolid was performed.

RESULTS

MRSA strain MIC90s were tedizolid 0.12-0.25 mg/L and linezolid 1-2 mg/L; for MSSA strains, MIC90s were tedizolid 0.12 mg/L and linezolid 1-2 mg/L. Two strains, WIS 441 and Seattle 106, with tedizolid MICs of 2 mg/L and 1 mg/L, respectively, had MICs above the FDA tedizolid breakpoint (0.5 mg/L). Tedizolid at free serum concentrations exhibited a bacteriostatic effect. Mean bacterial burdens in lungs (log10 cfu/g) for WIS 423-infected mice were: control, 11.2±0.5; tedizolid-treated (10 mg/kg), 3.40±1.87; linezolid-treated (40 mg/kg), 4.51±2.1; and vancomycin-treated (30 mg/kg), 5.21±1.93. For WIS 441-infected mice the (log10 cfu/g) values were: control, 9.66±0.8; tedizolid-treated, 3.18±1.35; linezolid-treated 5.94±2.19; and vancomycin-treated, 4.35±1.7.

CONCLUSIONS

These results suggest that tedizolid represents a promising therapeutic option for the treatment of CF-associated MRSA/MSSA infections, having potent in vivo activity and low resistance potential.

Pharmacokinetics and Safety of Single-dose Tedizolid Phosphate in Children 2 to <12 Years of Age

BACKGROUND

Infections with Gram-positive bacteria, including acute bacterial skin and skin structure infections (ABSSSIs), are common in children. We describe a single-dose pharmacokinetics and safety study of tedizolid phosphate, a new oxazolidinone under investigation for the treatment of ABSSSIs in children, in hospitalized participants 2 to <12 years of age.

METHODS

This open-label, multicenter, phase 1 trial (NCT02750761) enrolled hospitalized children 2 to <12 years of age receiving treatment for a confirmed/suspected Gram-positive bacterial infection. Participants were stratified by age (2 to <6 years and 6 to <12 years) to receive a single oral or intravenous dose of tedizolid phosphate. Evaluations included safety and pharmacokinetics of tedizolid phosphate and its active metabolite, tedizolid. Palatability of the oral suspension was also evaluated.

RESULTS

Thirty-two participants were enrolled and received 3-6 mg/kg of study medication. For both routes of administration, tedizolid phosphate was rapidly converted to tedizolid; median time to maximum tedizolid plasma concentration was 1-2 hours after initiation of the 1-hour intravenous infusion and 2-3 hours after oral dosing. The tedizolid mean terminal half-life was 5-6 hours and 6-7 hours for the intravenous and oral administration groups, respectively. The oral tedizolid phosphate suspension demonstrated high bioavailability comparable to that of the parenteral administration. A single dose of intravenous or oral tedizolid phosphate was well tolerated; no unexpected safety findings were observed.

CONCLUSIONS

Pharmacokinetic and safety observations provide the information necessary for the continued development of tedizolid phosphate for the treatment of Gram-positive infections in children, particularly ABSSSIs.

UPLC-MS/MS assay of Tedizolid in rabbit aqueous humor: Application to ocular pharmacokinetic study

Tedizolid phosphate (TZP) a prodrug of Tedizolid (TDZ) is a novel oxazolidinone antibiotic, used for the treatment of acute bacterial skin, skin structure infections and other serious gram positive and MRSA infections. In the present study, a sensitive UPLC-MS/MS analytical method was developed and validated for the quantification of TDZ in rabbit's aqueous humor (AqH) by using linezolid as internal standard (IS). Both TDZ and IS were separated on an Acquity™ HILIC column using an isocratic mobile phase comprising of acetonitrile: 20 mM ammonium acetate (85:15, v/v), eluted at 0.3mLmin^-1 flow rate with total run time of 3 min. The AqH samples were processed by protein precipitation method by using acetonitrile as precipitating agent. TDZ and IS were detected in positive mode using electrospray ionization source. The precursor to product ion transitions at m/z 371.15 to 343.17 for TDZ and m/z 338.18 to 296.22 for IS were used for the quantification in multiple reaction monitoring mode. The calibration curve was linear in the concentration range of 4.98-1000ngmL^-1 and the lower limit of detection was 1.97ngmL^-1 only. The method was validated following US-FDA-guidelines and the results of validation parameter were found within the set limits. The developed UPLC-MS/MS method was fast, sensitive and reliable for the quantification of TDZ in the rabbit AqH and was successfully employed for ocular pharmacokinetic study of TDZ in AqH after topical ocular application of TZP-containing formulations in rabbit eyes.

Tedizolid-Cyclodextrin System as Delayed-Release Drug Delivery with Antibacterial Activity

Progressive increase in bacterial resistance has caused an urgent need to introduce new antibiotics, one of them being oxazolidinones with their representative tedizolid. Despite the broad spectrum of activity of the parent tedizolid, it is characterized by low water solubility, which limits its use. The combination of the active molecule with a multifunctional excipient, which is cyclodextrins, allows preservation of its pharmacological activity and modification of its physicochemical properties. Therefore, the aim of the study was to change the dissolution rate and permeability through the model membrane of tedizolid by formation of solid dispersions with a cyclodextrin. The research included identification of tedizolid-hydroxypropyl-β-cyclodextrin (tedizolid/HP-β-CD) inclusion complex by thermal method (Differential Scanning Colorimetry), spectroscopic methods (powder X-ray diffraction, Fourier-Transform Infrared spectroscopy), and molecular docking. The second part of the research concerned the physicochemical properties (dissolution and permeability) and the biological properties of the system in terms of its microbiological activity. An increase in the dissolution rate was observed in the presence of cyclodextrin, while maintaining a high permeation coefficient and high microbiological activity. The proposed approach is an opportunity to develop drug delivery systems used in the treatment of resistant bacterial infections, in which, in addition to modifying the physicochemical properties caused by cyclodextrin, we observe a favorable change in the pharmacological potential of the bioactives.

Inhibition of mitochondrial translation overcomes venetoclax resistance in AML through activation of the integrated stress response

Venetoclax is a specific B cell lymphoma 2 (BCL-2) inhibitor with promising activity against acute myeloid leukemia (AML), but its clinical efficacy as a single agent or in combination with hypomethylating agents (HMAs), such as azacitidine, is hampered by intrinsic and acquired resistance. Here, we performed a genome-wide CRISPR knockout screen and found that inactivation of genes involved in mitochondrial translation restored sensitivity to venetoclax in resistant AML cells. Pharmacologic inhibition of mitochondrial protein synthesis with antibiotics that target the ribosome, including tedizolid and doxycycline, effectively overcame venetoclax resistance. Mechanistic studies showed that both tedizolid and venetoclax suppressed mitochondrial respiration, with the latter demonstrating inhibitory activity against complex I [nicotinamide adenine dinucleotide plus hydrogen (NADH) dehydrogenase] of the electron transport chain (ETC). The drugs cooperated to activate a heightened integrated stress response (ISR), which, in turn, suppressed glycolytic capacity, resulting in adenosine triphosphate (ATP) depletion and subsequent cell death. Combination treatment with tedizolid and venetoclax was superior to either agent alone in reducing leukemic burden in mice engrafted with treatment-resistant human AML. The addition of tedizolid to azacitidine and venetoclax further enhanced the killing of resistant AML cells in vitro and in vivo. Our findings demonstrate that inhibition of mitochondrial translation is an effective approach to overcoming venetoclax resistance and provide a rationale for combining tedizolid, azacitidine, and venetoclax as a triplet therapy for AML.

Therapeutic Options for Infections due to vanB Genotype Vancomycin-Resistant Enterococci

Enterococci are ubiquitous, facultative, anaerobic Gram-positive bacteria that mainly reside, as part of the normal microbiota, in the gastrointestinal tracts of several animal species, including humans. These bacteria have the capability to turn from a normal gut commensal organism to an invasive pathogen in patients debilitated by prolonged hospitalization, concurrent illnesses, and/or exposed to broad-spectrum antibiotics. The majority of vancomycin-resistant enterococcus (VRE) infections are linked to the vanA genotype; however, outbreaks caused by vanB-type VREs have been increasingly reported, representing a new challenge for effective antimicrobial treatment. Teicoplanin, daptomycin, fosfomycin, and linezolid are useful antimicrobials for infections due to vanB enterococci. In addition, new drugs have been developed (e.g., dalbavancin, telavancin, and tedizolid), new molecules will soon be available (e.g., eravacycline, omadacycline, and oritavancin), and new treatment strategies are progressively being used in clinical practice (e.g., combination therapies and bacteriophages). The aim of this article is to discuss the pathogenesis of infections due to enterococci harboring the vanB operon (vanBVRE) and their therapeutic, state-of-the-art, and future treatment options and provide a comprehensive and easy to use review for clinical purposes.

Safety and Tolerability of More than Six Days of Tedizolid Treatment

Tedizolid has demonstrated its efficacy and safety in clinical trials; however, data concerning its tolerability in long-term treatments are scarce. The aim of the study was to assess the indications and to describe the long-term safety profile of tedizolid. A multicentric retrospective study of patients who received tedizolid for more than 6 days was conducted. Adverse events (AEs) were identified from patients' medical records and laboratory data. The World Health Organization causality categories were used to discern AEs that were probably associated with tedizolid. Eighty-one patients, treated with tedizolid 200 mg once daily for a median (interquartile range [IQR]) duration of 28 (14 to 59) days, were included; 36 (44.4%) had previously received linezolid. The most common reasons for selecting tedizolid were to avoid linezolid potential toxicities or interactions (53.1%) or due to previous linezolid-related toxicities (27.2%). The most common indications were off-label, including prosthetic joint infections, osteomyelitis, and respiratory infections (77.8%). Overall, 9/81 patients (11.1%) experienced a probably associated AE. Two patients (2.5%) developed gastrointestinal disorders, 1 (1.2%) developed anemia, and 6 developed thrombocytopenia (7.4%) after a median (IQR) duration of treatment of 26.5 (17 to 58.5) days. Four (5%) patients discontinued tedizolid due to AEs. Among 23 patients with chronic renal failure (CRF), the rate of myelotoxicity was 17.4%, and only 8.7% had to stop tedizolid; 20 out of 22 with previous linezolid-associated toxicity had no AE. Long-term tedizolid treatments had good tolerance with rates of gastrointestinal AE and hematological toxicity lower than those reported with linezolid, particularly in patients with CRF and in those with a history of linezolid-associated toxicity.

Tedizolid (torezolid) for the treatment of complicated skin and skin structure infections

INTRODUCTION

Acute bacterial skin and skin structure infections (ABSSSI) are among the most frequent infectious diseases. Recently, several new antibiotics with activity against MRSA have been approved. Tedizolid, a second-generation oxazolidinone approved for ABSSSI offers theoretical advantages over first-generation oxazolidinones.

AREAS COVERED

A comprehensive online search of Medline, ClinicalTrials.gov, and conference presentations was made, selecting articles between January 2000 and April 2020. In this review, the authors discuss the chemical and microbiological properties of tedizolid, summarize its efficacy, safety, and potential role in the treatment of ABSSSI as well as the potential for future indications.

EXPERT OPINION

Tedizolid has proven to be non-inferior compared to linezolid for the treatment of ABSSSI in two registrational phase III clinical trials, being well tolerated. Tedizolid exhibits antibacterial activity against the most important ABSSSI pathogens (including multidrug-resistant strains of MRSA), as well as mycobacteria and Nocardia. It appears to have a safe profile, including decreased myelotoxicity and no significant drug interactions. Preliminary studies with longer duration of therapy seem to confirm these potential benefits. Overall, tedizolid expands the newly acquired armamentarium to treat ABSSSI. The role of tedizolid for other indications is under investigation and has yet to be determined.

Current role of oxazolidinones and lipoglycopeptides in skin and soft tissue infections

PURPOSE OF REVIEW

An increase of skin and soft tissue infections involving Staphylococcus aureus has been reported in community and hospital settings. Methicillin resistance in S. aureus is associated with treatment failure and increased mortality. Recently, new antimicrobials with enhanced activity against methicillin-resistant Staph. aureus have been approved for the treatment of skin and soft tissue infections. Among these, novel oxazolidinones and lipoglycopeptides represent options with favorable pharmacokinetic characteristics and safety profiles.

RECENT FINDINGS

Newly approved compounds include tedizolid, characterized by the availability of both oral and intravenous formulation and once daily administration and dalbavancin, a long-acting antimicrobial allowing for weekly administration. These new molecules present advantages, such as enhanced activity against multidrug-resistant Gram-positive bacteria and favorable safety profiles.

SUMMARY

We have reviewed the pharmacokinetic characteristics and the implications for use in skin and soft tissue infections of tedizolid and dalbavancin. Advantages associated with the use of these compounds include the possibility for early patient discharge, reduced hospital length of stay, and outpatient treatment, with potential impact on morbidity, mortality, and overall health-care costs.

Important new therapies for methicillin-resistant Staphylococcus aureus

Introduction: Methicillin-resistant Staphylococcus aureus (MRSA) infections represent a leading cause of infection-related morbidity and mortality worldwide. There has been a welcome increase in the number of agents available for the treatment of MRSA infection over the last decade and several clinical trials are currently investigating the role of new experimental strategies.Areas covered: The purpose of this manuscript is to review the efficacy and safety of recently approved anti-MRSA molecules as well as some newer agents currently under investigation with a specific focus on the potential role of these drugs in everyday clinical practice.Expert opinion: Many new drugs with an activity against MRSA have been recently approved or are in an advanced stage of development. All these compounds represent promising options to enhance our antibiotic armamentarium. However, data regarding the use of these new compounds in real-life terms are limited and their best placement in therapy and in terms of optimization of medical resources and balance of cost-effectiveness requires further investigation.

Tedizolid phosphate for the treatment of acute bacterial skin and skin-structure infections: an evidence-based review of its place in therapy

Introduction

Tedizolid phosphate is an oxazolidinone approved for the treatment of acute bacterial skin and skin-structure infections (ABSSSIs) and active against methicillin-resistant Staphylococcus aureus.

Aims

The objective of this article was to review the evidence for the efficacy and safety of tedizolid phosphate for the treatment of ABSSSI.

Evidence review

Approval of tedizolid phosphate for the treatment of ABSSSI was based on the results of two phase III randomized controlled trials, ESTABLISH-1 (NCT01170221) and ESTABLISH-2 (NCT01421511), comparing 6-day once-daily tedizolid vs 10-day twice-daily linezolid. In ESTABLISH-1, noninferiority was met with early clinical response rates of 79.5% and 79.4% in tedizolid and linezolid groups, respectively (difference 0.1%, 95% CI –6.1% to 6.2%, with a 10% noninferiority margin). In ESTABLISH-2, noninferiority was met with 85% and 83% rates of early clinical response in tedizolid and linezolid groups, respectively (difference 2.6%, 95% CI –3.0% to 8.2%). Pooled data from ESTABLISH-1 and ESTABLISH-2 indicated a lower frequency of thrombocytopenia in tedizolid-treated than in linezolid-treated patients.

Conclusion

Tedizolid offers the option of an intravenous to oral switch, allows once-daily administration, and presents lower risk of myelotoxicity when a 6-day course is used for the treatment of ABSSSI. Greater economic cost associated with this antibiotic could be offset by its shorter treatment duration and possibility of oral administration in routine clinical practice, although either sponsored or nonsponsored postmarketing observational experience remains essential for ultimately confirming the effectiveness and tolerability of tedizolid outside clinical trials.

Comparative in vitro potency and kill curve activity of tedizolid and linezolid against Gram-positive bacteria isolated from Chinese hospitalized patients in 2013-2016

We compared the kill-curve activity of tedizolid and linezolid at clinically relevant (total or free plasma, lung) concentrations against methicillin-resistant Staphylococcus aureus (MRSA) and penicillin-resistant Streptococcus pneumoniae (PRSP) isolated from Chinese patients. Tedizolid had greater in vitro potency than linezolid against staphylococci, streptococci and enterococci species (tedizolid minimum inhibitory concentration (MIC) range: ≤ 0.016-0.5 µg/mL; linezolid MIC range: 0.25-2 µg/mL). In kill-curve experiments, growth of MRSA was inhibited at tedizolid concentration of 0.6 µg/mL (i.e. 4.8 × MIC; MIC = 0.125 µg/mL) and linezolid concentration of 2 µg/mL (2× MIC; MIC = 1 µg/mL). Against PRSP, tedizolid at a concentration of 0.25 µg/mL (representing its MIC) was bacteriostatic, but exerted a bactericidal effect at higher concentrations. Results were similar for linezolid, however, even at 21 µg/mL, a small proportion of organisms survived beyond 24 h. The results demonstrated the potency of tedizolid against clinical strains of Gram-positive pathogens supporting its use as a suitable alternative to linezolid in Chinese patients.

Perspectives on synthetic pharmacotherapy for the treatment of nosocomial pneumonia

Introduction: Nosocomial pneumonia is the second most common infection in hospital settings, resulting in substantial increases in morbidity, mortality, and length of hospital stay. The rapid increase in resistance of nosocomial pathogens to many antibiotics and the high dissemination of resistance genes highlight the need for innovative approaches to combat difficult-to-treat nosocomial respiratory infections. Areas covered: This review summarizes the synthetic antimicrobials that are currently in development for the treatment of nosocomial pneumonia, focusing on antibiotics in the final phases of clinical development and on the strategies employed by novel synthetic antimicrobial peptides. Expert opinion: Several novel synthetic antimicrobials are currently in the pipeline, and it appears that new antimicrobial peptides or mimetics will soon be made available, expanding the opportunities to treat nosocomial pneumonia. However, the approval process for use in the treatment of nosocomial pneumonia is arduous. Given that significant investments by pharmaceutical companies have ended in failure to obtain the approval of regulatory agencies, novel platforms for antimicrobial discovery are needed. The identification of new and fully synthetic chemical structures with activity against nosocomial pathogens needs to be followed by preclinical studies in large animals and by pharmacokinetic and pharmacodynamic studies in specific critically ill populations to assess lung penetration.

In Vitro and Intracellular Activity of Imipenem Combined with Tedizolid, Rifabutin, and Avibactam against Mycobacterium abscessus

Mycobacterium abscessus infections are difficult to treat because of their resistance to many antibiotics. In vitro, tedizolid combined with imipenem displayed a moderate synergistic effect (fractional inhibitory concentration index, 0.41) but no bactericidal activity. Intracellularly, tedizolid 2 μg/ml (half of the MIC), corresponding to the peak serum concentration, increased the efficacy of imipenem at 8 and 32 μg/ml. Addition of avibactam and rifabutin, alone or in combination, improved the activity of the imipenem-tedizolid combination.

Use of Translational Pharmacokinetic/Pharmacodynamic Infection Models To Understand the Impact of Neutropenia on the Efficacy of Tedizolid Phosphate

Tedizolid phosphate, the prodrug of the active antibiotic tedizolid, is an oxazolidinone for the treatment of acute bacterial skin and skin structure infections. Studies in a mouse thigh infection model demonstrated that tedizolid has improved potency and pharmacokinetics/pharmacodynamics (PK/PD) compared with those of linezolid. Subsequent studies showed that the efficacy of tedizolid was enhanced in immunocompetent (IC) mice compared with neutropenic (immunosuppressed [IS]) mice, with stasis at clinically relevant doses being achieved only in the presence of granulocytes. The tedizolid label therefore contains a warning about its use in neutropenic patients. This study reevaluated the PK/PD of tedizolid and linezolid in the mouse thigh infection model in IC and IS mice using a methicillin-resistant Staphylococcus aureus (MRSA) strain (ATCC 33591) and a methicillin-susceptible S. aureus (MSSA) strain (ATCC 29213). The antistaphylococcal effect of doses ranging from 1 to 150 mg/kg of body weight tedizolid (once daily) or linezolid (twice daily) was determined at 24, 48, and 72 h after initiating treatment. In IC mice, stasis was achieved in the absence of antibiotics, and both tedizolid and linezolid reduced the burden further beyond a static effect. In IS mice, tedizolid achieved stasis against MRSA ATCC 33591 and MSSA ATCC 29213 at 72 h at a human clinical dose of 200 mg, severalfold lower than that in earlier studies. Linezolid achieved a static effect against MRSA ATCC 33591 in IS mice at a dose lower than that used clinically. This study demonstrates that, with time, both tedizolid and linezolid at clinically relevant exposures achieve stasis in neutropenic mice with an MRSA or MSSA thigh infection.

Evaluation of in vitro susceptibility of Gram-positive pathogens from a tertiary care hospital in Singapore to a novel oxazolidinone, tedizolid, by a gradient diffusion method and broth microdilution

We compared the in vitro antimicrobial activities of tedizolid and linezolid on the Sensititre broth microdilution system for Gram-positive cocci isolates (n=146) from skin and skin structure infections and bloodstream infections, bronchoalveolar lavage and sputum. These pathogens included 40 methicillin-resistant Staphylococcus aureus, 38 coagulase-negative staphylococci, 20 Enterococcus faecalis and 48 beta-haemolytic Streptococcus spp. Susceptibility was simultaneously determined for 48 vanA vancomycin-resistant enterococci isolates 2013-2016 from rectal swabs (23 E. faecalis and 25 E. faecium, of which 4 were linezolid-non-susceptible). MIC_90s for tedizolid were fourfold to eightfold lower than linezolid on the Sensititre and ranged from 0.12 to 0.5 µg/mL for the different pathogen groups. All isolates were susceptible to tedizolid except two vanA E. faecium strains (MICs of 1 and 2 µg/mL, respectively). Categorical and essential agreement for tedizolid were 99.48% and 92%, respectively, between Liofilchem gradient diffusion and Sensititre methods. Overall, the drug exhibited excellent activity against the surveyed Gram-positive pathogens.

Real-Life Evidence for Tedizolid Phosphate in the Treatment of Cellulitis and Wound Infections: A Case Series

Introduction

Tedizolid phosphate 200 mg, once daily for 6 days, has recently been approved for the treatment of patients with acute bacterial skin and skin structure infections (ABSSSIs) in several countries; however, clinical experience in real-life settings is currently limited. Here, we report on the use of tedizolid with an extended treatment duration for complex and severe ABSSSIs in real-world clinical settings.

Methods

Two patients with cellulitis and two patients with surgical site infection (SSI), aged 26–60 years, were treated with tedizolid phosphate 200 mg, intravenous/oral (IV/PO) or IV only, once daily at four different institutions.

Results

Two morbidly obese patients had non-necrotizing, non-purulent severe cellulitis, which were complicated by sepsis or systemic inflammatory response syndrome plus myositis. One female patient failed on first-line empiric therapy with IV cefalotin, clindamycin and imipenem (3–4 days), and was switched to IV/PO tedizolid (7 + 5 days). One male patient received IV clindamycin plus IV/PO tedizolid (5 + 5 days), but clindamycin was discontinued on Day 3 due to an adverse event. For both patients, clinical signs and symptoms improved within 72 h, and laboratory results were normalized by Days 7 and 8, respectively. Two other patients (one obese, diabetic female with chronic hepatitis and chronic obstructive pulmonary disease) had complicated SSIs occurring 10 days after hernia repair with mesh or 3 months after spinal fusion surgery with metal implant. First patient with previous methicillin-resistant Staphylococcus aureus (MRSA) bacteremia received a 7-day tedizolid IV course empirically. The second patient with culture-confirmed MRSA infection received a 14-day IV course. Both patients responded within 72 h, and local and systemic signs normalized by end of treatment. There were no reports of thrombocytopenia.

Conclusion

Tedizolid phosphate 200 mg for 7–14 days was a favored treatment option for patients with severe/complex ABSSSIs, and was effective following previous treatment failure or in late-onset infections.

Funding

Editorial assistance and the article processing charges were funded by Bayer AG, Berlin, Germany.

Pharmacokinetics, Pharmacodynamics, and Tolerability of Single-Dose Oral LCB01-0371, a Novel Oxazolidinone with Broad-Spectrum Activity, in Healthy Volunteers

LCB01-0371 is a novel oxazolidinone with broad-spectrum activity against Gram-positive pathogens in both in vitro studies and animal infection models. The objectives of this study were to evaluate its safety, tolerability, pharmacokinetics, and pharmacodynamics following single ascending doses. Single oral doses of 600 mg linezolid, a placebo, or LCB01-0371 of between 50 mg and 3,200 mg were tested in 69 healthy male subjects. Blood and urine were sampled, LCB01-0371 concentrations were measured, and the serum inhibitory and bactericidal titers of LCB01-0371 and linezolid were determined. LCB01-0371 was well tolerated up to 2,400 mg. The most common drug-related clinical and laboratory adverse events were nausea with or without vomiting, decreased neutrophil counts, and increased total bilirubin levels. The frequency of adverse events and drug-related adverse events was similar among the treatment groups. The systemic exposure was approximately dose proportional over the range of 50 mg to 800 mg, which includes the anticipated clinical dose. The mean clearance, renal clearance, and volume of distribution were significantly decreased at higher doses (above 800 mg). LCB01-0371 exhibited early bacteriostatic activity against all tested strains except for Streptococcus pneumoniae strains, and the potency of LCB01-0371 at 800 mg was similar to that of linezolid at the therapeutic dose (600 mg). However, LCB01-0371 had less bactericidal activity than linezolid. Taken together, LCB01-0371 was well tolerated, exhibited approximate dose proportionality within the anticipated clinically relevant dose range, and showed bacteriostatic and bactericidal activity comparable to that of linezolid. These results support the further clinical development of LCB01-0371. (This study has been registered at ClinicalTrials.gov under registration no. NCT01554995.).

Effect of food on the pharmacokinetic characteristics of a single oral dose of LCB01-0371, a novel oxazolidinone antibiotic

Background

LCB01-0371 is a novel oxazolidinone antibiotic that blocks protein production by binding to bacterial 23S ribosomes. This antibiotic is active against Gram-positive bacteria. This study aimed to evaluate the effect of food on the pharmacokinetics (PKs) of LCB01-0371 and evaluate its safety profile.

Subjects and methods

A randomized, open-label, two-way crossover study was performed in 18 healthy Korean male subjects. All subjects received a single oral 800 mg dose of LCB01-0371 in each period under fed or fasting condition with a 7-day washout in between. The fed condition was defined as consumption of a meal of 800–1,000 kcal containinĝ50% of fat content. Serial blood samples were collected over 24 h after dosing, and the PK parameters were calculated by noncompartment analysis. All available data of the subjects who received LCB01-0371 at least once were included in the safety data summaries.

Results

In the fed condition, both the maximum plasma concentration (C_max) and the total systemic exposure (area under the plasma concentration–time curve from time zero to the last observed time point [AUC_last]) decreased by ~33% and 10%, respectively. The time to reach C_max was delayed by ~1.25 h in the fed condition, whereas the mean elimination half-life remained similar in both conditions. In the fed/fasting condition, the geometric mean ratios and 90% CI of the C_max and AUC_last were 0.666 (0.470–0.945) and 0.897 (0.761–1.057), respectively. There were no drug-related adverse events (AEs) or serious AEs.

Conclusion

Although the T_max after a single oral 800 mg dose of LCB01-0371 was slightly delayed under the fed condition compared to the fasting condition, the total systemic exposure was similar under both conditions. Therefore, LCB01-0371 could be administered regardless of food intake.

Clinical Pharmacokinetics and Pharmacodynamics of Oxazolidinones

Oxazolidinones are a class of synthetic antimicrobial agents with potent activity against a wide range of multidrug-resistant Gram-positive pathogens including methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci. Oxazolidinones exhibit their antibacterial effects by inhibiting protein synthesis acting on the ribosomal 50S subunit of the bacteria and thus preventing formation of a functional 70S initiation complex. Currently, two oxazolidinones have been approved by the US Food and Drug Administration: linezolid and more recently tedizolid. Other oxazolidinones are currently under investigation in clinical trials. These antimicrobial agents exhibit a favourable pharmacokinetic profile with an excellent bioavailability and a good tissue and organ penetration. In-vitro susceptibility studies have shown that oxazolidinones are bacteriostatic against enterococci and staphylococci, and bactericidal for the majority of strains of streptococci. In the context of emergence of resistance to glycopeptides, oxazolidinones have become an effective alternative to vancomycin treatment frequently associated with nephrotoxicity. However, oxazolidinones, and linezolid in particular, are associated with significant adverse events, myelosuppression representing the main unfavourable side effect. More recently, tedizolid has been shown to effectively treat acute bacterial skin and skin structure infections. This newer oxazolidinone offers the advantages of once-daily dosing and a better safety profile in healthy volunteer studies (fewer gastrointestinal and haematological side effects). The potential use of tedizolid for other infections that could require longer therapy warrants further studies for positioning this new oxazolidinone in the available antimicrobial armamentarium. Moreover, other oxazolidinones are currently under active investigation.

Comparative Assessment of Tedizolid Pharmacokinetics and Tissue Penetration between Diabetic Patients with Wound Infections and Healthy Volunteers via In Vivo Microdialysis

Herein, we present pharmacokinetic and tissue penetration data for oral tedizolid in hospitalized patients with diabetic foot infections (DFI) compared with healthy volunteers. Participants received oral tedizolid phosphate 200 mg every 24 h for 3 doses to achieve steady state. A microdialysis catheter was inserted into the subcutaneous tissue near the margin of the wound for patients or into thigh tissue of volunteers. Following the third dose, 12 blood and 14 dialysate fluid samples were collected over 24 h to characterize tedizolid concentrations in plasma and interstitial extracellular fluid of soft tissue. Mean ± standard deviation (SD) tedizolid pharmacokinetic parameters in plasma for patients compared with volunteers, respectively, were as follows: maximum concentration (C_max), 1.5 ± 0.5 versus 2.7 ± 1.1 mg/liter (P = 0.005); time to C_max (T_max) (median [range]), 5.9 (1.2 to 8.0) versus 2.5 (2.0 to 3.0 h) (P = 0.003); half-life (t_1/2), 9.1 ± 3.6 versus 8.9 ± 2.2 h (P = 0.932); and plasma area under the concentration-time curve for the dosing interval (AUC _p ), 18.5 ± 9.7 versus 28.7 ± 9.6 mg · h/liter (P = 0.004). The tissue area under the concentration-time curve (AUC _t ) for the dosing interval was 3.4 ± 1.5 versus 5.2 ± 1.6 mg · h/liter (P = 0.075). Tissue penetration median (range) was 1.1 (0.3 to 1.6) versus 0.8 (0.7 to 1.0) (P = 0.351). Despite lower plasma C_max and delayed T_max values for patients with DFI relative to healthy volunteers, the penetration into and exposure to tissue were similar. Based on available pharmacodynamic thresholds for tedizolid, the plasma and tissue exposures using the oral 200 mg once-daily regimen are suitable for further study in treatment of DFI.

In Vitro Susceptibility Testing of Tedizolid against Isolates of Nocardia

There is a paucity of efficacious antimicrobials (especially oral) against clinically relevant species of Nocardia To date, all species of Nocardia have been susceptible to linezolid, the first commercially available oxazolidinone. Tedizolid is a new oxazolidinone with previously reported improved in vitro and in vivo (intracellular) potency against multidrug-resistant strains of Mycobacterium sp. and Nocardia brasiliensis Using the current Clinical and Laboratory Standards Institute-recommended broth microdilution method, 101 isolates of Nocardia spp., including 29 Nocardia cyriacigeorgica, 17 Nocardia farcinica, 13 Nocardia nova complex, 21 Nocardia brasiliensis, 5 Nocardia pseudobrasiliensis, and 5 Nocardia wallacei isolates and 11 isolates of less common species, were tested for susceptibility to tedizolid and linezolid. For the most common clinically significant species of Nocardia, tedizolid MIC₅₀ values were 0.25 μg/ml for N. nova complex, N. brasiliensis, N. pseudobrasiliensis, and N. wallacei, compared to linezolid MIC₅₀ values of 1, 2, 0.5, and 1 μg/ml, respectively. Tedizolid and linezolid MIC₉₀ values were 2 μg/ml for N. nova complex and N. brasiliensis Tedizolid MIC₅₀ and MIC₉₀ values for both N. cyriacigeorgica and N. farcinica were 0.5 μg/ml and 1 μg/ml, respectively, compared to linezolid MIC₅₀ and MIC₉₀ values of 2 and 4 μg/ml, respectively. Based on MIC₉₀ values, this study showed that tedizolid was 2- to 3-fold more active than linezolid in vitro against most common species of Nocardia, with the exception of the N. nova complex and N. brasiliensis, for which values were the same. These results may warrant evaluation of tedizolid as a potential treatment option for Nocardia infections.

In vitro activity of tedizolid against the Mycobacterium abscessus complex

Infections due to Mycobacterium abscessus carry a poor prognosis since this rapidly growing mycobacterium is intrinsically resistant to most antibiotics. Here, we evaluate the in vitro activity of the new oxazolidinone tedizolid against a collection of 44M. abscessus clinical isolates. The MIC₅₀s and MIC₉₀s of tedizolid (2 and 8μg/mL, respectively) were 2- to 16-fold lower than those of linezolid. There was no difference between the 3M. abscessus subspecies. Time-kill assays did not show any bactericidal activity at 4- and 8-fold the MIC. Combination of tedizolid with clarithromycin was synergistic against 1 out of 6 isolates, while indifferent interactions were observed for tedizolid combined with tigecycline, ciprofloxacin, and amikacin.

Determination of Tedizolid susceptibility interpretive criteria for gram-positive pathogens according to clinical and laboratory standards institute guidelines

For effective antibacterial therapy, physicians require qualitative test results using susceptibility breakpoints provided by clinical microbiology laboratories. This article summarizes the key components used to establish the Clinical Laboratory Standards Institute (CLSI) breakpoints for tedizolid. First, in vitro studies using recent surveillance and clinical trial isolates ascertained minimal inhibitory concentration (MIC) distributions against pertinent organisms, including staphylococci, streptococci, and enterococci. Studies in animal models of infection determined rates of antibacterial efficacy and survival following administration of tedizolid phosphate at doses equivalent to those in humans. Pharmacokinetic and pharmacodynamic analyses examined the relationship between plasma concentrations and MICs against the target organism. Finally, clinical trials assessed clinical and microbiologic outcomes by MIC. All these data were evaluated and combined to obtain the ratified CLSI susceptibility criteria for tedizolid of ≤0.5μg/mL for Staphylococcus aureus, Streptococcus pyogenes, Streptococcus agalactiae, and Enterococcus faecalis and ≤0.25μg/mL for Streptococcus anginosus group.