Dose optimization of tacrolimus with therapeutic drug monitoring and CYP3A5 polymorphism in patients with myasthenia gravis.

BACKGROUND AND PURPOSE: Tacrolimus is beneficial for treatment of myasthenia gravis (MG) and has a narrow therapeutic range. Therefore, therapeutic drug monitoring is essential for tacrolimus to optimize dosage and prevent adverse reactions. However, no studies have explored the factors influencing tacrolimus blood concentration in patients with MG. Thus, we aimed to analyze these factors and discuss how to optimize tacrolimus dosage for MG treatment.

METHODS

Data regarding clinical characteristics, therapeutic drugs and adverse reactions of patients with MG who received tacrolimus were collected from 2013 to 2015 at Beijing Hospital. Tacrolimus whole-blood concentrations were measured by chemiluminescent microparticle immunoassay and CYP3A5*3 gene polymorphism was detected by digital fluorescence molecule hybridization fluorescence. Regression analysis was applied to analyze the factors influencing blood concentrations and adverse reactions.

RESULTS

It was shown that there was a correlation between concentration and dosage. Furthermore, co-administration of proton pump inhibitor and clarithromycin and CYP3A5*3 gene polymorphism could significantly increase the tacrolimus whole-blood levels. Adverse reactions were related to blood concentration, CYP3A5 genetic polymorphisms and combined medication though logistic regression analysis.

CONCLUSIONS

The concentration of tacrolimus is affected by many factors. Therapeutic drug monitoring and detection of CYP3A5 gene polymorphism was essential for dosage optimization in patients with MG.