Population pharmacokinetics and limited sampling strategy for therapeutic drug monitoring of mycophenolate mofetil in Japanese patients with lupus nephritis

Dosing mycophenolate mofetil for lupus nephritis is complicated by the pharmacokinetic complexity of its active metabolite, mycophenolic acid (MPA), and multiple blood draws for full exposure assessment pose a clinical challenge, particularly in Asian populations where data are limited. This retrospective study in 34 adult Japanese lupus nephritis patients developed a population pharmacokinetic model using Phoenix NLME, then compared single- and double-sample limited sampling strategies against full AUC measurement. Renal function and serum albumin significantly affected MPA clearance, and a double sampling strategy at 1 and 4 hours post-dose showed the best agreement with observed AUC, while a single sample at 6 hours performed best among single-sample options. This first Japanese population pharmacokinetic model for MPA in lupus nephritis, along with its limited sampling strategies, could support safer, more individualized therapy.