Determination of trimethoprim in low-volume human plasma by liquid chromatography

Area of Science:

• Pharmacology and Pharmaceutical Analysis
• Analytical Chemistry
• Clinical Pharmacokinetics

Background:

• Trimethoprim is a vital anti-infective medication used for urinary tract infections, respiratory infections, and Pneumocystis pneumonia.
• Trimethoprim exhibits selective inhibition of cytochrome P450 2C8 in vitro, suggesting potential in vivo applications.
• Accurate quantification of trimethoprim in biological matrices is essential for therapeutic drug monitoring and pharmacokinetic research.

Purpose of the Study:

• To develop and validate a simplified high-performance liquid chromatography (HPLC) method for the determination of trimethoprim in human plasma.
• To establish a reliable analytical tool for assessing trimethoprim pharmacokinetics in clinical settings.

Main Methods:

• Plasma samples were prepared using simple protein precipitation with perchloric acid.
• Chromatographic separation was performed on a Synergi Polar-RP column.
• A mobile phase of ammonium formate-acetonitrile-methanol (pH 3.0) was employed, with detection at 280 nm.

Main Results:

• The developed HPLC method demonstrated high precision, with intra-day and inter-day coefficients of variation ranging from 1.1% to 1.9% and 0.9% to 4.1%, respectively.
• The assay is characterized by its simplicity, cost-effectiveness, and precision.
• The method is directly applicable to analyzing steady-state trimethoprim pharmacokinetics in human studies.

Conclusions:

• A robust and efficient HPLC method for trimethoprim quantification in human plasma has been successfully developed.
• This validated assay provides a valuable tool for pharmacokinetic investigations of trimethoprim.
• The method's practicality supports its routine use in clinical research and therapeutic drug monitoring.