Cefiderocol Sulfate Tosylate

Physical and Quality Control Parameters

Appearance: White to off-white lyophilized powder, hygroscopic, odorless; appears as a loose mass after lyophilization, and forms a clear solution after reconstitution (WHO).

Solubility: Easily soluble in water (solubility ≥100 mg/mL, 25℃), slightly soluble in methanol, almost insoluble in ethanol and acetonitrile; pH of reconstituted solution is 5.0-7.0, suitable for intravenous infusion (WHO).

Stability

The solid form should be sealed, protected from light, and stored frozen below -15℃, with a shelf life of 24 months; it is highly hygroscopic and easily hydrolyzed after moisture absorption, requiring vacuum aluminum-plastic packaging (WHO).

The reconstituted solution is stable for 6 hours at room temperature and stable for 24 hours under refrigeration at 2-8℃; avoid mixing with solutions containing heavy metal ions to prevent complexation reactions that may affect efficacy.

Key Quality Control Indicators (API level)

Chemical Purity: ≥96.0% (HPLC area normalization method, detection wavelength 254 nm) (WHO)

Related Substances: Single impurity ≤0.1%, total impurities ≤0.5% (HPLC impurity control method) (WHO)

Moisture Content: ≤3.0% (Karl Fischer method) (WHO)

Sulfate Content: 2.8%-3.2% (ion chromatography) (WHO)

Tosyl Content: 12.0%-14.0% (HPLC external standard method) (WHO)

Sterility: Meets the requirements of the Chinese Pharmacopoeia sterility test method

Bacterial Endotoxin: ≤0.1 EU/mg

III. Pharmacological Effects and Antibacterial Spectrum

1. Mechanism of Action

Cefiderocol chelates Fe³⁺ through its catechol group, forming an iron-drug complex, which is recognized and transported into the cell by bacterial iron transporters, bypassing the outer membrane permeability barrier.

The cefiderocol released intracellularly binds with high affinity to bacterial PBPs (especially PBP3), inhibiting peptidoglycan cross-linking in the cell wall, leading to bacterial lysis and death. The methoxyimino side chain resists hydrolysis by β-lactamases such as ESBLs and AmpC enzymes, making it effective against multidrug-resistant strains.

2. Antibacterial Spectrum (covering multidrug-resistant Gram-negative bacteria)

Bacterial Category Sensitive Strains

Enterobacteriaceae Carbapenem-resistant *Escherichia coli*, *Klebsiella pneumoniae*, *Enterobacter cloacae*

Non-fermenting bacteria Carbapenem-resistant *Pseudomonas aeruginosa*, *Acinetobacter baumannii*, *Stenotrophomonas maltophilia*

Others *Haemophilus influenzae*, *Moraxella catarrhalis*