Pharmacokinetic Analysis of Gatifloxacin and Dexamethasone in Rabbit Ocular Biofluid Using a Sensitive and Selective...

Area of Science:

• Pharmacology and Toxicology
• Analytical Chemistry
• Ophthalmology

Background:

• Bacterial keratitis (BK) is a serious cornea infection that can lead to blindness.
• Topical fluoroquinolones and corticosteroids are common treatments for BK.
• Accurate quantification of drugs in tear fluid is crucial for pharmacokinetic studies.

Purpose of the Study:

• To develop and validate a rapid, selective, and sensitive bioanalytical method for simultaneous quantification of Gatifloxacin (GAT) and Dexamethasone (DEX).
• To apply the validated method for preclinical pharmacokinetic analysis of GAT and DEX in rabbit tear fluid.

Main Methods:

• Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was employed for simultaneous quantification.
• Separation was achieved using an Agilent Zorbax C18 column with a mobile phase of formic acid in water and methanol.
• Detection was performed in positive electrospray ionization multiple reaction monitoring (MRM) mode.

Main Results:

• The method demonstrated linearity over a range of 1.56–400 ng/mL for both GAT and DEX.
• High precision and accuracy were achieved, meeting USFDA regulatory guidelines.
• The validated method was successfully used for pharmacokinetic analysis in rabbit tear fluid.

Conclusions:

• A robust LC-MS/MS method for quantifying GAT and DEX in tear fluid has been successfully developed and validated.
• This method is suitable for preclinical pharmacokinetic studies of topical ophthalmic formulations.
• The validated assay facilitates the assessment of drug absorption and disposition in the ocular environment.