What is known and objective The pharmacokinetics (PK) and pharmacodynamics (PD) of levofloxacin were investigated following administration of levofloxacin injection in healthy Chinese volunteers for optimizing dosing regimen. Methods The PK study included single‐dose (750 mg/150 mL) and multiple‐dose (750 mg/150 mL once daily for 7 days) phases. The concentration of levofloxacin in blood and urine was determined using HPLC method. Both non‐compartmental and compartmental analyses were performed to estimate PK parameters. Taking fC_max/MIC ≥5 and fAUC_24 h/MIC ≥30 as a target, the cumulative fraction of response (CFR) of levofloxacin 750 mg for treatment of community‐acquired pneumonia (CAP) was calculated using Monte Carlo simulation. The probability of target attainment (PTA) of levofloxacin at various minimal inhibitory concentrations (MICs) was also evaluated. Results and discussion The results of PK study showed that the C_max and AUC_0–∞ of levofloxacin were 14·94 μg/mL and 80·14 μg h/mL following single‐dose infusion of levofloxacin. The half‐life and average cumulative urine excretion ratio within 72 h post‐dosing were 7·75 h and 86·95%, respectively. The mean C_ss,max, C_ss,min and AUC_0–τ of levofloxacin at steady state following multiple doses were 13·31 μg/mL, 0·031 μg/mL and 103·7 μg h/mL, respectively. The accumulation coefficient was 1·22. PK/PD analysis revealed that the CFR value of levofloxacin 750‐mg regimen against Streptococcus pneumoniae was 96·2% and 95·4%, respectively, in terms of fC_max/MIC and fAUC/MIC targets. What is new and conclusion The regimen of 750‐mg levofloxacin once daily provides a satisfactory PK/PD profile against the main pathogenic bacteria of CAP, which implies promising clinical and bacteriological efficacy for patients with CAP. A large‐scale clinical study is warranted to confirm these results.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) continues to spread rapidly worldwide. This study is the first to report the tolerability, safety, pharmacokinetics (PK), and immunogenicity of a recombinant human anti-SARS-CoV-2 monoclonal antibody, etesevimab (CB6, JS016, LY3832479 or LY-CoV016), in healthy adults. This paper involves a randomized, double-blind, placebo-controlled, phase 1 study. A total of 40 participants were enrolled to receive a single intravenous dose of either etesevimab or a placebo in one of four sequential ascending intravenous dose cohorts. All 40 participants completed the study. Seventeen (42.5%) participants experienced 22 treatment emergent adverse events (TEAEs) that were drug-related, and the rates of these TEAEs among different dose cohorts were numerically comparable. No difference was observed between the combined etesevimab group and the placebo group. The exposure after etesevimab infusion increased in an approximately proportional manner as the dose ^{increased from 2.5 to 50 mg/kg. The} elimination half-life ^{(t1/2) value did not differ among different dose} cohorts and was estimated to be around 4 weeks. Etesevimab was well tolerated after administration of a single dose at a range of 2.5 mg/kg to 50 mg/kg in healthy Chinese adults. The PK profiles of etesevimab in healthy volunteers showed typical monoclonal antibody distribution and elimination characteristics. (This study has been registered at ClinicalTrials.gov under identifier NCT04441918.)

Contezolid (MRX-I), a new oxazolidinone, is an antibiotic in development for treating complicated skin and soft tissue infections caused by resistant Gram-positive bacteria. This was a thorough QT study conducted in 52 healthy subjects who were administered oral contezolid at a therapeutic (800 mg) dose, a supratherapeutic (1,600 mg) dose, placebo, and oral moxifloxacin at 400 mg in four separate treatment periods. The pharmacokinetic profile of contezolid was also evaluated.

Contezolid (MRX-I), a novel oxazolidinone antibiotic, was recently approved for the treatment of serious Gram-positive infections. The pharmacokinetics and disposition of [ ¹⁴ C]contezolid were investigated in a single-dose human mass balance study.