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Background. Post hoc analyses of clinical trial data suggested that linezolid may be more effective than vancomycin for treatment of methicillin-resistant Staphylococcus aureus (MRSA) nosocomial pneumonia. This study prospectively assessed efficacy and safety of linezolid, compared with a dose-optimized vancomycin regimen, for treatment of MRSA nosocomial pneumonia. Methods. This was a prospective, double-blind, controlled, multicenter trial involving hospitalized adult patients with hospital-acquired or healthcare—associated MRSA pneumonia. Patients were randomized to receive intravenous linezolid (600 mg every 12 hours) or vancomycin (15 mg/kg every 12 hours) for 7-14 days. Vancomycin dose was adjusted on the basis of trough levels. The primary end point was clinical outcome at end of study (EOS) in evaluable per-protocol (PP) patients. Prespecified secondary end points included response in the modified intent-to-treat (mITT) population at end of treatment (EOT) and EOS and microbiologic response in the PP and mITT populations at EOT and EOS. Survival and safety were also evaluated. Results. Of 1184 patients treated, 448 (linezolid, n = 224; vancomycin, n = 224) were included in the mITT and 348 (linezolid, n = 172; vancomycin, n = 176) in the PP population. In the PP population, 95 (57.6%) of 165 linezolid-treated patients and 81 (46.6%) of 174 vancomycin-treated patients achieved clinical success at EOS (95% confidence interval for difference, 0.5%-21.6%; P = .042). All-cause 60-day mortality was similar (linezolid, 15.7%; vancomycin, 17.0%), as was incidence of adverse events. Nephrotoxicity occurred more frequently with vancomycin (18.2%; linezolid, 8.4%). Conclusions. For the treatment of MRSA nosocomial pneumonia, clinical response at EOS in the PP population was significantly higher with linezolid than with vancomycin, although 60-day mortality was similar.

Treatment of acute bacterial skin infection is becoming more complicated as antimicrobial resistance increases. In this trial of dalbavancin, a lipoglycopeptide with a long half-life, once-weekly dosing was shown to be noninferior to vancomycin–linezolid for treating infection. Acute bacterial skin and skin-structure infections are among the most common reasons for the hospitalization of adults in the United States today. 1 These infections are caused most often by Staphylococcus aureus and streptococci. 2 Methicillin-resistant S. aureus (MRSA) accounts for many of these infections and presents a particular treatment challenge because current therapies are limited by toxicity, resistance, or the lack of an oral formulation. 3 Associated medical costs are substantial. 4 Dalbavancin (Durata Therapeutics) is a lipoglycopeptide antibiotic agent with in vitro and in vivo activity against gram-positive pathogens, including a minimal inhibitory concentration (MIC) required to inhibit the growth of 90% . . .

This study assessed the tolerability and pharmacokinetic (PK) properties of a new-generation oxazolidinone, contezolid (MRX-I), and its major inactive metabolite, M2, after single oral administrations of 800, 1200, and 1600 mg in the fed state, and compared the efficacy of 3 dosing regimens in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infection based on PK/pharmacodynamic (PD) analysis. A Phase I study at a single study center was conducted with 2 parts. In the first part, 20 healthy subjects received a single oral dose of 1200 or 1600 mg of contezolid or placebo in the fed state in a double-blind, placebo-controlled, dose-escalation tolerance study. In the second part of the study, 52 subjects received a single oral dose of 800 mg of contezolid in the fed state in a single-center, randomized, blinded, 4-period, crossover, thorough QT study. Noncompartmental analyses were used to evaluate the PK properties of contezolid and M2. Steady-state concentrations of contezolid following the 3 dosing regimens (800, 1200, and 1600 mg q12h) were simulated by employing a newly developed 2-compartmental PK model. The minimum inhibitory concentration (MIC) distributions of contezolid were analyzed in 178 Staphylococcus, Enterococcus, and Streptococcus clinical isolates. Monte Carlo simulations were conducted to predict the efficacy of the 3 dosing regimens to obtain probability of target attainment and cumulative fraction of response. Single-dose oral administrations of 800, 1200, and 1600 mg of contezolid were well tolerated in healthy subjects in the fed state, and nonlinear PK was observed. The mean plasma exposures to M2 exceeded 17.3% of contezolid exposure in the 3 groups. Both MIC50 and MIC90 (MICs that inhibit the growth of 50% and 90% of microorganisms, respectively) of contezolid against MRSA were 1 mg/L with clinical isolates from China. PK/PD analysis and Monte Carlo simulations predicted that 800 mg q12h of oral contezolid would be efficacious against MRSA infection, with a MIC of ≤4 mg/L (probability of target attainment, >90%; cumulative fraction of response, >90%). Contezolid is a well-tolerated treatment option for MRSA infection, including at supratherapeutic doses up to 1600 mg. The regimen of 800 mg q12h could achieve efficacy in treating bacterial infection with MRSA. To our knowledge, this is the first PK study to predict that a dosing regimen of 800 mg q12h of oral contezolid is sufficient for treating MRSA infection, with a MIC of ≤4 mg/L. A Phase III study of this suggested dosing regimen is being conducted. Chinadrugtrials.org.cn identifier: CTR20161074.

TBI-223, a novel oxazolidinone for tuberculosis, is designed to provide improved efficacy and safety compared to linezolid in combination with bedaquiline and pretomanid (BPaL). We aim to optimize the dosing of TBI-223 within the BPaL regimen for enhanced therapeutic outcomes. TBI-223 is investigated in preclinical monotherapy, multidrug therapy, and lesion penetration experiments to describe its efficacy and safety versus linezolid. A translational platform incorporating linezolid and BPaL data from preclinical experiments and 4 clinical trials (NCT00396084, NCT02333799, NCT03086486, NCT00816426) is developed, enabling validation of the framework. TBI-223 preclinical and Phase 1 data (NCT03758612) are applied to the translational framework to predict clinical outcomes and optimize TBI-223 dosing in combination with bedaquiline and pretomanid. Results indicate that daily doses of 1200–2400 mg TBI-223 may achieve efficacy comparable to the BPaL regimen, with >90% of patients predicted to reach culture conversion by two months. In this work, authors aim to optimize the dosing of TBI-223, a novel oxazolidinone for tuberculosis, using a translational platform which incorporates preclinical and clinical trial data.

New antibiotics are needed to treat infections caused by drug-resistant bacteria. Tedizolid is a novel oxazolidinone antibacterial drug designed to provide enhanced activity against Gram-positive pathogens. We aimed to assess the efficacy and safety of intravenous to oral tedizolid for treatment of patients with acute bacterial skin and skin-structure infections. ESTABLISH-2 was a randomised, double-blind, phase 3, non-inferiority trial done between Sept 28, 2011, and Jan 10, 2013, at 58 centres in nine countries. Patients (aged ≥12 years) with acute bacterial skin and skin-structure infections (cellulitis or erysipelas, major cutaneous abscess, or wound infection) that had a minimum lesion area of 75 cm2 and were suspected or documented to be associated with a Gram-positive pathogen, were randomly assigned (1:1), via an interactive voice-response system with block randomisation, to receive intravenous once-daily tedizolid (200 mg for 6 days) or twice-daily linezolid (600 mg for 10 days), with optional oral step-down. Randomisation was stratified by geographic region and type of acute bacterial skin and skin-structure infection. The primary endpoint was early clinical response (≥20% reduction in lesion area at 48–72 h compared with baseline), with a non-inferiority margin of −10%. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT01421511. 666 patients were randomly assigned to receive tedizolid (n=332) or linezolid (n=334). 283 (85%) patients in the tedizolid group and 276 (83%) in the linezolid group achieved early clinical response (difference 2·6%, 95% CI −3·0 to 8·2), meeting the prespecified non-inferiority margin. Gastrointestinal adverse events were less frequent with tedizolid than linezolid, taking place in 52 (16%) of 331 patients and 67 (20%) of 327 patients in the safety population. Treatment-emergent adverse events leading to discontinuation of study drug were reported by one (<1%) patient in the tedizolid group and four (1%) patients in the linezolid group. Intravenous to oral once-daily tedizolid 200 mg for 6 days was non-inferior to twice-daily linezolid 600 mg for 10 days for treatment of patients with acute bacterial skin and skin-structure infections. Tedizolid could become a useful option for the treatment of acute bacterial skin and skin-structure infections in the hospital and outpatient settings. Cubist Pharmaceuticals.

Background. The oxazolidinone PNU-100480 is superior to linezolid against experimental murine tuberculosis. Two metabolites contribute to but do not fully account for its superiority. This study examined the safety, tolerability, pharmacokinetics, and mycobactericidal activity of single ascending doses of PNU-100480. Methods. Nineteen healthy volunteers received 2 escalating single oral doses (35–1500 µg) of PNU-100480 or placebo. Eight subjects received 4 daily doses of 300 mg of linezolid. Drug concentrations and bactericidal activity against Mycobacterium tuberculosis in whole-blood bactericidal culture were measured. Results. All doses were safe and well tolerated. PNU-100480 doses to 1000 mg were well absorbed and showed approximately proportional increases in exposures of parent and metabolites. The geometric mean maximal concentrations of PNU-100480, PNU-101603, and PNU-101244 (sulfoxide and sulfone metabolites) at 1000 mg were 839, 3558, and 54 ng/mL, respectively. The maximal whole-blood bactericidal activity (−0.37 ± .06 log/day) occurred at combined PNU levels ⩾2 times the minimum inhibitory concentration. The observed geometric mean maximal concentration for linezolid was 6425 ng/mL. Its maximal whole-blood bactericidal activity also occurred at ⩾2 times the minimum inhibitory concentration, but it was only −0.16 ± .05 log/day (P<.001). Neither drug showed enhanced activity at higher concentrations. Conclusions. Single doses of PNU-100480 to 1000 mg were well tolerated and exhibited antimycobacterial activity superior to 300 mg of linezolid at steady state. Additional studies are warranted to define its role in drugresistant tuberculosis. Clinical trial registration ClinicalTrials.gov identifiers NCT00871949 and NCT00990990.

Cadazolid is a novel quinoxolidinone antibiotic developed for treating Clostridium difficile infection. We aimed to investigate the safety and efficacy of cadazolid compared with vancomycin in patients with C difficile infection. IMPACT 1 and IMPACT 2 were identically designed, multicentre, double-blind, placebo-controlled, non-inferiority, randomised phase 3 trials. IMPACT 1 was done in Australia, Brazil, Canada, France, Germany, Italy, the Netherlands, Peru, Poland, Romania, Spain, and the USA, and IMPACT 2 was done in Argentina, Belgium, Brazil, Canada, Chile, Croatia, Czech Republic, Greece, Hungary, Israel, Romania, Slovakia, South Korea, the UK, and the USA. Patients (aged 18 years or older) with mild-to-moderate or severe C difficile infection (diarrhoea with positive glutamate dehydrogenase and toxin A or B enzyme immunoassays) were randomly assigned (1:1) with a randomisation list stratified by centre and C difficile infection episode type (block size of four), and allocation was masked to investigators and participants. Patients received either oral cadazolid 250 mg twice daily with vancomycin-matching placebo capsule four times daily or oral vancomycin 125 mg four times a day with cadazolid-matching placebo suspension twice daily for 10 days, with 30 days of follow-up. The primary efficacy outcome was non-inferiority (margin −10%) of cadazolid versus vancomycin for clinical cure in the modified intention-to-treat and per-protocol populations. Clinical cure was defined as resolution of diarrhoea with no additional treatment for C difficile infection. These trials are registered with ClinicalTrials.gov, numbers NCT01987895 (IMPACT 1) and NCT01983683 (IMPACT 2). Between March 28, 2014, and March 24, 2017, for IMPACT 1, and Dec 13, 2013, and May 2, 2017, for IMPACT 2, 1263 participants were randomly assigned to receive cadazolid (306 in IMPACT 1 and 298 in IMPACT 2) or vancomycin (326 in IMPACT 1 and 311 in IMPACT 2). In the modified intention-to-treat population in IMPACT 1, 253 (84%) of 302 had clinical cure in the cadazolid group versus 271 (85%) of 318 in the vancomycin group. In IMPACT 2, 235 (81%) of 290 versus 258 (86%) of 301 had clinical cure. In the per-protocol population, 247 (88%) of 282 versus 264 (92%) of 288 had clinical cure in IMPACT 1 and 214 (87%) of 247 versus 237 (92%) of 259 in IMPACT 2. Non-inferiority for clinical cure to vancomycin was shown in IMPACT 1 but not in IMPACT 2 (IMPACT 1 treatment difference: −1·4 [95% CI −7·2 to 4·3] for modified intention to treat and −4·1 [–9·2 to 1·0] for per protocol; IMPACT 2: −4·7 [–10·7 to 1·3] for modified intention to treat and −4·9 [–10·4 to 0·6] for per protocol). The safety and tolerability profiles of the two antibiotics were similar. Cadazolid was safe and well tolerated but did not achieve its primary endpoint of non-inferiority to vancomycin for clinical cure in one of two phase 3 C difficile infection trials. Therefore, further commercial development of cadazolid for C difficile infection is unlikely. Actelion Pharmaceuticals.

We recently reported strong bactericidal activity of the oxazolidinone PNU-100480 and its ability to increase the initial bactericidal effect of various combinations of first-line tuberculosis drugs and moxifloxacin in a murine model. To investigate whether the addition of PNU-100480 to the standard first-line regimen of rifampin, isoniazid, and pyrazinamide could shorten the duration of treatment necessary to prevent relapse after treatment discontinuation. Following aerosol infection with Mycobacterium tuberculosis H37Rv and a 13-day incubation period, control mice were treated with the first-line regimen while test mice received the same regimen with PNU-100480 or linezolid added for the first 2 or 4 months. Efficacy was assessed on the basis of quantitative cultures of lung homogenates performed monthly during treatment and 3 months after completion of 3, 4, 5, or 6 months of treatment to determine the relapse rate. After 2 months of treatment, mice receiving PNU-100480 in addition to the first-line regimen had lung CFU counts two orders of magnitude lower than control mice receiving the first-line regimen alone. Relapse rates after 4 months of treatment were 90, 35, and 5% when PNU-100480 was added to the first-line regimen for 0, 2, and 4 months, respectively. When the total treatment duration was 3 months, relapse rates were 85 and 35 to 45% when mice received PNU-100480 for 2 and 3 months, respectively; all control mice remained culture positive at the time of treatment completion with 17 to 72 CFU per lung. Addition of linezolid to the first-line regimen had an antagonistic effect resulting in higher CFU counts and failure to render mice culture-negative in 4 months of treatment. Together with previous findings, these results confirm that PNU-100480, which is now in Phase I clinical testing, has sterilizing activity in the murine model and suggest that it may be capable of shortening treatment duration for drug-susceptible as well as drug-resistant tuberculosis in humans.

Contezolid is a new oxazolidinone antibacterial agent, and its pharmacokinetic (PK) characteristics and safety in super-elderly patients remain poorly understood. Contezolid PK parameters were analyzed in enrolled super-elderly patients (≥ 80 years), with systematic assessment of steady-state profiles and adverse events. Thirteen super-elderly patients (mean age: 94.9 ± 4.8 years) were included in the study. The plasma concentrations of contezolid peaked at 2-3h post administration. Both C and AUC exhibited dose-dependent increases across regimens (400 mg q24h, 400 mg q12h, and 800 mg q12h). When receiving a dosage of 800 mg q12h, super-elderly patients demonstrated comparable C (20.32 vs 26.45 mg/L), AUC (97.80 vs 90.38 h·mg/L), and clearance (9.08 vs 10.20 L/h) values to those of healthy adults but prolonged T (2.67 vs 0.57 h) and shorter t values (2.33 vs 4.84 h). For pathogens with a minimum inhibitory concentration (MIC) ≤1 mg/L, 400 mg of contezolid q12h resulted in a > 90% probability of target attainment (PTA), whereas doubling the dose to 800 mg q12h resulted in a PTA > 90% against pathogens with MICs of 2-4 mg/L. Contezolid was well tolerated, with mild gastrointestinal adverse reactions (vomiting, n=2) and elevated AST (n=1), γ-GT (n=2), and lipase (n=1) levels. According to a self-controlled analysis of 9 patients who switched from linezolid to contezolid, the incidence of thrombocytopenia was significantly lower when taking contezolid (11.1% vs 77.8%). Contezolid has comparable PKs in super-elderly and healthy adults. While a dosage of 400 mg q12h is sufficient for pathogens with MICs ≤ 1 mg/L, a higher dosage of 800 mg q12h is recommended for higher MICs (2-4 mg/L), with both doses demonstrating favorable safety. ChiCTR2200056377; 4/2/2022.

Zolmitriptan (ZT) is a selective serotonin agonist that is used for the treatment of migraine. It belongs to BCS class III with high solubility and low permeability. Besides, the drug is subjected to pre-systemic metabolism. Accordingly, new Zolmitriptan/chitosan nanostructured lipid carriers (ZT/CT NLCs) coated with Tween 80 (stealthy layer) have been developed to overcome such demerits. The NLCs were developed by combining ultrasonication and double emulsion (w/o/w) techniques. The lipids were Gelucire and Labrasol. Herein, the quality by design (2 full factorial design) was scrupulously followed, where critical process parameters and critical quality attributes were predefined. The optimized formulation (F8) was fully characterized with respect to entrapment efficiency (%EE), percentage yield (% yield), particle size, size distribution (PDI), zeta potential (ZP), morphological appearance (TEM). In vitro release, stability study and pharmacodynamic evaluations were also assessed. The optimized freeze dried formula was dispensed in in situ gelling hard gelatin capsule encompassing pectin and guar gum for further in vitro and pharmacodynamic evaluations. The optimized spherical nanoparticles experienced high percentage EE and yield (78.14% and 60.19%, respectively), low particle size and PDI (343.87 nm and 0.209, respectively), as well as high negative ZP (-25.5 mV). It showed good physical stability at refrigerated conditions. The NLCs dispensed in in situ gelling hard gelatin capsule comprising pectin and guar gum experienced sustained release for 30 h and significantly maintained the pharmacological effect in mice up to 8 h (p < 0.001). ZT, a BCS class III drug that suffers from poor permeability and pre-systemic metabolism, was successfully maneuvered as nanostructured lipid carrier particles (NLCs). The incorporation of the NLCs in in situ gelling hard gelatin capsules fulfilled a dual function in increasing permeability, as well as sustaining the pharmacodynamic effect. This result would open new vistas in improving the efficacy of other class III drugs.