Quantification of Ceftazidime in the Vitreous Humor Using Ultra-performance Convergence Chromatography-Tandem Mass...

Area of Science:

• Pharmacokinetics and Drug Metabolism
• Analytical Chemistry
• Ophthalmology

Background:

• Postoperative bacterial endophthalmitis poses a significant risk of vision loss.
• Intravitreal antibiotics, commonly ceftazidime and vancomycin, are crucial for immediate treatment.
• Adequate unbound ceftazidime exposure above the minimum inhibitory concentration is vital for efficacy.

Purpose of the Study:

• To develop and validate an ultra-performance convergence chromatography-tandem mass spectrometry (UPC2-MS/MS) method.
• To quantify ceftazidime concentrations in the vitreous humor following intravitreal injection.
• To support investigations into ceftazidime disposition in endophthalmitis treatment.

Main Methods:

• Vitreous humor samples (20 µL) underwent protein precipitation with an internal standard (meropenem-d6).
• Analysis was performed using a Waters Acquity UPC2 system coupled to a Waters Xevo TQ-S micro mass spectrometer.
• Method validation followed European Medicines Agency and US Food and Drug Administration guidelines, assessing linearity, LOQ, accuracy, precision, carryover, and stability.

Main Results:

• The UPC2-MS/MS method demonstrated excellent linearity (r2 > 0.990) within the 1.3–99.6 mg/L range.
• Inaccuracy and imprecision were consistently below 15%.
• A significant carryover effect necessitated injecting one blank sample after each patient sample to ensure accurate quantification.

Conclusions:

• The developed UPC2-MS/MS method provides rapid and reliable quantification of ceftazidime in vitreous humor.
• The method features a short run time of 5 minutes, enhancing efficiency.
• The assay was successfully applied to 72 clinical samples, demonstrating its clinical utility.