An abbreviated area-under-the-curve monitoring for tacrolimus in patients with liver transplants

This study aims to assess the predictability of individual tacrolimus (FK) concentrations at different time points for the area under the curve (AUG) and to find the best sampling time for the abbreviated AUC to predict the total body exposure of FK. A total of 23 FK blood concentration versus time profiles (11 blood samples per 12 hours) was studied in 12 stable patients with liver transplants at steady state. Each AUC was calculated by the trapezoidal rule, and the relationship between individual concentrations or abbreviated AUC and total AUC was determined by linear regression. The trough concentrations from the morning dose predict AUC better than the trough concentration from the evening dose (r(2) = 0.71 for morning dose and r(2) = 0.35 for evening dose). In the case of single drug concentration, the 4-hour concentration could predict the total AUC reasonably well (r(2) = 0.73). From stepwise multiple regression, the abbreviated AUC at 1, 2.5, 6, and 9 hours could predict the total AUC most accurately (r(2) = 0.99). This study shows that the four levels at 1, 2.5, 6, and 9 hours or 1, 4, and 12 hours as an abbreviated AUC is as good as a full pharmacokinetic study. Alternatively, 4-hour concentration is a good predictor of the total body exposure of FK in the stable patients with liver transplants.