Linezolid
[CAS# 165800-03-3]

Identification

• Classification: API >> Synthetic anti-infective drugs >> Antifungal drugs
• Name: Linezolid
• Synonyms: (S)-N-[[3-(3-Fluoro-4-morpholinylphenyl)-2-oxo-5-oxazolidinyl]methyl]acetamide
• Molecular Formula: C₁₆H₂₀FN₃O₄
• Molecular Weight: 337.35
• CAS Registry Number: 165800-03-3
• EC Number: 605-416-1
• SMILES: CC(=O)NC[C@H]1CN(C(=O)O1)C2=CC(=C(C=C2)N3CCOCC3)F

Properties

• Solubility: 10 mM (DMSO)

Safety Data

• Hazard Symbols: GHS08 Danger
• Hazard Statements: H372
• Precautionary Statements: P260-P264-P270-P273-P319-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Specific target organ toxicity - repeated exposure	STOT RE	1	H372
Specific target organ toxicity - repeated exposure	STOT RE	2	H373
Acute toxicity	Acute Tox.	4	H302
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Reproductive toxicity	Repr.	2	H361
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	4	H312
Acute toxicity	Acute Tox.	4	H332

Discovory and Applicatios

Linezolid is an antibiotic that belongs to the oxazolidinone class and is primarily used to treat infections caused by Gram-positive bacteria, including resistant strains such as methicillin-resistant *Staphylococcus aureus* (MRSA) and vancomycin-resistant *Enterococcus* (VRE). Discovered in the late 1990s, linezolid was developed to address the growing problem of antibiotic resistance, particularly in hospital settings where multidrug-resistant bacteria were becoming a significant threat to patient health.

The discovery of linezolid represents an important step in the development of synthetic antibiotics. Unlike many other antibiotics derived from natural sources, linezolid was the result of chemical synthesis, designed to inhibit bacterial protein synthesis by targeting the 50S ribosomal subunit. This unique mode of action disrupts the formation of the initiation complex for protein synthesis, which effectively halts bacterial growth. The discovery was driven by the need to develop antibiotics with novel mechanisms to combat resistant pathogens that had become impervious to traditional treatments.

Linezolid’s effectiveness against Gram-positive bacteria, including strains resistant to multiple antibiotics, made it a crucial tool for treating serious infections such as pneumonia, skin and soft tissue infections, and bacteremia. It is particularly valuable for hospital-acquired infections, where the prevalence of antibiotic-resistant bacteria is higher. Because of its oral and intravenous formulations, linezolid is versatile in both outpatient and inpatient settings, allowing for continuity of care after hospital discharge.

One of the major benefits of linezolid is its ability to penetrate well into tissues, including lung tissue, making it effective against respiratory infections like community-acquired and nosocomial pneumonia. Additionally, it has excellent bioavailability when administered orally, making it convenient for patients transitioning from hospital to home treatment without the need for continued intravenous therapy. This feature improves patient compliance and reduces the overall burden on healthcare facilities.

Despite its benefits, linezolid also has limitations, particularly in its use over long periods. One of the most notable adverse effects is the risk of bone marrow suppression, which can lead to thrombocytopenia. This side effect typically manifests after two weeks of therapy, so close monitoring of blood counts is required for patients undergoing extended treatment. Peripheral and optic neuropathy are other potential adverse effects, particularly when linezolid is used for more than 28 days.

Linezolid has also been studied for its potential in treating tuberculosis (TB), particularly multidrug-resistant TB. While not traditionally used for this purpose, its activity against *Mycobacterium tuberculosis* has made it a subject of interest in TB research. Clinical trials have explored its role in combination therapies for extensively drug-resistant TB (XDR-TB), although its side effects remain a concern in long-term treatment.

Overall, linezolid has become an essential antibiotic in the treatment of resistant bacterial infections. Its synthetic origin and novel mechanism of action have provided a solution to the challenges posed by antibiotic resistance, particularly in healthcare environments. Continued research into its applications, as well as monitoring its long-term safety profile, ensures that linezolid remains a valuable tool in modern medicine.