A Common mdr1 Gene Polymorphism is Associated With Changes in Linezolid Clearance

Area of Science:

• Pharmacogenetics
• Clinical Pharmacology
• Antimicrobial Chemotherapy

Background:

• Linezolid plasma exposure shows high variability.
• The P-glycoprotein (ABCB1) transporter is a potential factor influencing linezolid pharmacokinetics.
• Investigating ABCB1 polymorphisms is crucial for understanding linezolid variability.

Purpose of the Study:

• To determine if ABCB1 gene polymorphisms predict linezolid pharmacokinetics in critically ill patients.
• To assess the impact of ABCB1 variants on linezolid clearance, half-life, volume of distribution, and exposure (AUC, Ctrough).

Main Methods:

• Genotyping of ABCB1 polymorphisms using real-time PCR.
• Analysis of linezolid plasma concentrations (Ctrough, AUC) via nonlinear mixed-effects modeling.
• Evaluation of pharmacokinetic parameters in relation to ABCB1 genotypes.

Main Results:

• The ABCB1 c.3435C>T polymorphism significantly affected linezolid clearance, with lower values in individuals with the T allele.
• Significant differences in terminal half-life and volume of distribution were observed between genotypes.
• Simulations indicated a potentially better AUC/MIC ratio for CC genotype individuals against key bacterial pathogens.

Conclusions:

• ABCB1 polymorphisms play a role in linezolid pharmacokinetics, warranting further pharmacogenetic investigation.
• Incorporating genetic evaluation and therapeutic drug monitoring can advance precision medicine in antimicrobial therapy.
• Personalized dosing strategies based on ABCB1 genotype may optimize linezolid treatment efficacy.