Contezolid acefosamil sodium (MRX-4) is a novel orally active oxazolidinone antibiotic under investigation for the treatment of complicated skin and soft tissue infections (cSSTI) caused by drug-resistant Gram-positive bacteria. It possesses strong efficacy against these pathogens while significantly minimizing the risks of myelosuppression and monoamine oxidase inhibition (MAOI) [1][2].

Contezolid (MRX-I) demonstrates strong efficacy against a broad spectrum of Gram-positive clinical isolates, including staphylococci, streptococci, and enterococci. Its potency extends to multidrug-resistant (MDR) organisms, such as MRSA, methicillin-resistant Streptococcus epidermidis (MRSE), penicillin-resistant Streptococci (PRSP), and vancomycin-resistant enterococci (VRE)[2].

Oral absorption of Contezolid (MRX-I) occurs rapidly in mouse, rat, and dog, with peak plasma concentrations at 0.5-2.6 h postdose. In these species respectively, dose-normalized Cmax/dose was 524, 1065, and 259 ng/mL/(mg/kg); dose-normalized AUC0-t/dose was 1654, 3703, and 1664 ng·h/mL/(mg/kg); T1/2 is 1, 1.5, and 3 h; and oral bioavailability is 69%, 109%, and 37%[2]. Contezolid (MRX-I) shows no obvious toxicity [2]. Contezolid (MRX-I, 100 mg/kg, once daily) significantly reduced the bacterial load in lungs compared to untreated controls[3].