Pharmacokinetics and safety of single and multiple doses of ACHN-490 injection administered intravenously in healthy subjects.

ACHN-490 is an aminoglycoside with activity against multidrug-resistant pathogens, including those resistant to currently used aminoglycosides. Two randomized, double-blind, placebo-controlled clinical studies investigated the pharmacokinetics (PK), safety, and tolerability of ACHN-490 injection in healthy subjects. Study 1 used a parallel-group design with escalating single (SD) and multiple doses (MD). Study 2 explored a longer duration of the highest dose tolerated in the first study. Subjects were randomly assigned to receive either ACHN-490 injection or a placebo administered by a 10-min intravenous infusion. Study 1 enrolled 39 subjects (30 active and 9 placebo) and consisted of a single dose of 1 mg/kg body weight followed by ascending SD and MD cohorts of 4, 7, 11, and 15 mg/kg for 10, 10, 5, and 3 days, respectively. Study 2 enrolled 8 subjects (6 active and 2 placebo) who received 15 mg/kg for 5 days. Safety was assessed from adverse event (AE) reporting, standard clinical laboratory procedures, and testing for renal, cochlear, and vestibular function. ACHN-490 exhibited linear and dose-proportional PK, with agreement between the studies for PK parameters assessed. The 15-mg/kg dose did not accumulate with repeated dosing over 5 days. Mean steady-state (±standard deviation) area under the concentration-time curve from 0 to 24 h (AUC(0-24)), maximum concentration of drug in serum (C(max)), half-life (t(1/2)), clearance, and volume of distribution at steady state (V(ss)) for the 15-mg/kg, day 5 dose were 239 ± 45 h·mg/liter, 113 ± 17 mg/liter, 3 ± 0.3 h, 1.1 ± 0.1 ml/min/kg, and 0.24 ± 0.04 liters/kg, respectively. AEs were mild to moderate and rapidly resolved. No evidence of nephrotoxicity or ototoxicity was observed.

Combined retrospective analysis of seven phase II and III trials of the efficacy of linezolid in the treatment of pneumonia caused by multidrug-resistant Streptococcus pneumoniae.

BACKGROUND: Antimicrobial resistance among Streptococcus pneumoniae is of concern. Up to 30% of pneumococcal isolates worldwide are multidrug resistant. OBJECTIVE: The objective of this analysis was to assess the effectiveness of linezolid for the treatment of pneumonia caused by S pneumoniae, including multidrug-resistant S pneumoniae (MDRSP). METHODS: Data from 7 Phase II and III clinical trials that assessed the efficacy of linezolid in community- or hospital-acquired pneumonia were pooled. Adults and children (aged ≤12 years) received linezolid 600 mg and 10 mg/kg, respectively, IV or PO q12h for 7 to 14 days, with the exception of patients with documented bacteremia who could be treated for up to 28 days. Patients with a confirmed baseline isolate of S pneumoniae, including MDRSP, were assessed for clinical and microbiological outcomes. MDRSP was defined as an isolated strain of S pneumoniae that was resistant to ≥3 classes of antibiotics. Clinical cure was defined as the resolution of clinical signs and symptoms of pneumonia compared with baseline, with either improvement or absence of progression of abnormalities on chest radiography. Microbiological eradication was defined as documented or presumed eradication at the test-of-cure (TOC) visit. Results from patients with indeterminate or missing outcomes at TOC were not included in the analyses. RESULTS: Of the patients with no bacteremia and treated with linezolid, 19 adults had MDRSP and 165 had non-MDRSP, and 3 children had MDRSP and 7 had non-MDRSP. Clinical cure and microbiological eradication rates were not significantly different between those infected with an MDRSP or non-MDRSP pathogen, respectively, in adults (16/19 [84%] and 150/164 [91%]) and children (3/3 [100%] and 7/7 [100%]). CONCLUSION: Linezolid was efficacious for the treatment of pneumonia caused by S pneumoniae, including multidrug-resistant strains.

Complicated skin and skin-structure infections and catheter-related bloodstream infections: noninferiority of linezolid in a phase 3 study.

BACKGROUND: Catheter-related bloodstream infection (CRBSI) causes substantial morbidity and mortality, but few randomized, controlled studies have been conducted to guide therapeutic interventions. METHODS: To determine whether linezolid would be noninferior to vancomycin in patients with CRBSI, we conducted an open-label, multicenter, comparative study. Patients with suspected CRBSI were randomized to receive linezolid or vancomycin (control group). The primary end point was microbiologic outcome at test of cure 1-2 weeks after treatment, as assessed by step-down procedure. The first analysis population was complicated skin and skin structure infection (cSSSI) in patients with suspected CRBSI; patients with CRBSI were analyzed if noninferiority criteria (lower bound of the 95% confidence interval [CI] not outside -15%) were met. RESULTS: Noninferiority criteria were met for cSSSI (microbiologic success rate for linezolid recipients, 89.6% [146 for 163 patients]; for the control group, 89.9% [134 of 149]; 95% CI, -7.1 to 6.4) and CRBSI (for linezolid recipients, 86.3% [82 of 95]; for the control group, 90.5% [67 of 74]; 95% CI, -13.8 to 5.4). The frequency and severity of adverse events were similar between groups. Mortality rates were 10.4% for linezolid recipients (28 of 269 patients) and 10.1% for control subjects (26 of 257) in the modified intent-to-treat population (i.e., all patients with gram-positive baseline culture) through test of cure, and they were 21.5% for linezolid recipients (78 of 363) and 16.0% for the control group (58 of 363; 95% CI, -0.2 to 11.2) for all treated patients through poststudy treatment day 84. CONCLUSIONS: Linezolid demonstrated microbiologic success rates noninferior to those for vancomycin in patients with cSSSIs and CRBSIs caused by gram-positive organisms. Patients with catheter-related infections must be carefully investigated for the heterogeneous underlying causes of high morbidity and mortality, particularly for infections with gram-negative organisms.

Efficacy and safety of linezolid compared with vancomycin in a randomized, double-blind study of febrile neutropenic patients with cancer.

BACKGROUND: Gram-positive pathogens can cause serious infections in neutropenic patients with cancer, and vancomycin therapy is often initiated empirically. Linezolid may offer an option for these patients. METHODS: To compare the safety and efficacy of linezolid and vancomycin in febrile, neutropenic patients with cancer, we conducted a double-blind, multicenter equivalence study. Eligible patients with proven or suspected infection due to a gram-positive pathogen were randomized to receive linezolid or vancomycin. RESULTS: Clinical success rates 7 days after completion of therapy (primary end point) were equivalent between groups in the intent-to-treat (ITT) analysis (linezolid, 219 [87.3%] of 251 patients; vancomycin, 202 [85.2%] of 237 patients; 95% CI, -4.1 to 8.1; P=.52), modified ITT analysis, clinically evaluable analysis, and microbiologically evaluable analysis, as well as between subsets analyzed by malignancy and infection type. Mean time to defervescence was shorter for linezolid than vancomycin in the modified ITT (6.6 vs. 8.5 days; P=.04) and microbiologically evaluable subsets (5.9 vs. 9.1 days; P=.01), although post hoc analyses revealed delayed recovery of absolute neutrophil counts for linezolid in these subsets (P<.05). There were no between-group differences in microbiologic success rates in the modified ITT subset (41 [57.7%] of 71 patients vs. 29 [50.0%] of 58 patients; P=.38) and microbiologically evaluable subsets, as well as in mortality rates in the ITT subset (17 [5.6%] of 304 patients vs. 23 [7.6%] of 301 patients; P=.31) and all subsets. Distribution of adverse events, including reported hematologic events, was similar between groups, except that linezolid was associated with fewer drug-related adverse events (52 [17.2%] of 303 patients vs. 72 [24.0%] of 300 patients; P=.04) and fewer cases of drug-related renal failure (1 [0.3%] of 303 patients vs. 7 [2.3%] of patients; P=.04). CONCLUSIONS: Linezolid demonstrated efficacy and similar safety outcomes equivalent to those for vancomycin in febrile neutropenic patients with cancer.