High-Speed Analysis of Linezolid following the Draft Guidance of International Harmonization of Pharmacopoeias

Importance of the Topic

Linezolid is a synthetic oxazolidinone antibiotic introduced in the early 2000s and listed in major pharmacopeias.
Harmonization of analytical methods across USP, EP and JP enables streamlined drug quality control and higher laboratory throughput.

Objectives and Study Overview

The study demonstrates high-speed analysis of linezolid by comparing the USP assay method with an ultra-high-performance liquid chromatography (UHPLC) protocol derived from the JP/USP/EP harmonization draft. Shimadzu Nexera™ Series and Shim-pack Scepter™ C18 columns serve as the analytical platform.

Methodology and Instrumentation

High-speed conditions were established by adjusting column dimensions, particle size and flow rate following harmonization guidelines.

Key method parameters:

• Gradient elution from 20 % to 100 % organic over 7.6 min and re-equilibration to 20 % by 12.7 min
• Flow rate reduction from 1.5 mL/min (USP) to 0.45 mL/min (UHPLC) with 50×2.0 mm, 1.9 µm column
• Injection of 2 µL sample, column temperature 30 °C, UV detection at 254 nm

Instrumentation Used

• Shimadzu Nexera Series UHPLC system
• Shim-pack Scepter C18 columns: 75×4.6 mm, 5 µm and 50×2.0 mm, 1.9 µm
• Mobile phases composed of methanol, acetonitrile and 1.4 g/L monobasic potassium phosphate buffer

Main Results and Discussion

Both USP and UHPLC methods achieved clear separation of linezolid and impurity D. System suitability criteria were met under high-speed conditions:

• Resolution >3.0 between linezolid and compound D
• Tailing factors ≤1.5
• Relative standard deviation <1 %

Relative retention times for impurities remained within ±0.1 units, confirming method consistency.

Benefits and Practical Applications

• Run time reduction from 30 min to approximately 12.7 min
• Preserved chromatographic performance without extensive revalidation
• Simplified method transfer across international pharmacopeial standards

Future Trends and Opportunities

• Incorporation of harmonized UHPLC methods into official compendia
• Expanded use of superficially porous and sub-2 µm particle columns for efficiency gains
• Automation and integration with laboratory information management systems for real-time QA/QC

Conclusion

High-speed UHPLC analysis of linezolid based on draft harmonization guidelines was successfully implemented using Shim-pack Scepter C18 columns, achieving required system suitability and enabling high-throughput pharmaceutical testing.

Reference

(1) International Harmonization (Stage 4), Pharmaceuticals and Medical Devices Agency.