Use

Monitoring whole blood tacrolimus concentration is crucial during therapy, particularly when coadministered with cytochrome P450 (CYP) 3A4 substrates, inhibitors, or inducers. It aids in adjusting doses to optimize immunosuppression while minimizing toxicity and evaluating patient compliance. Tacrolimus, a macrolide antibiotic derived from the fungus Streptomyces tsukubaensis, inhibits calcineurin to suppress T cells and is metabolized by cytochrome P450 (CYP) 3A4. The narrow therapeutic range requires careful monitoring to prevent adverse effects, especially at high concentrations.