Tacrolimus is a well-established immunosuppressive agent for the treatment and prevention of solid organ graft rejection. It is available as an immediate-release, twice-daily formulation (Tacrolimus BID) and a prolonged-release, once-daily formulation (Tacrolimus QD). In a previous study of the pharmacokinetics (PK) of these formulations, mean systemic exposure [area under the curve from 0 to 24 hours (AUC0-24)] of tacrolimus on day 1 was approximately 30% lower for Tacrolimus QD than for Tacrolimus BID; by day 14, systemic exposure was similar; however, the mean dose of Tacrolimus QD was higher to achieve similar systemic exposure as Tacrolimus BID.
Wlodarczyk, Z., Ostrowski, M., Mourad, M., Krämer, B. K., Abramowicz, D., Oppenheimer, F., Miller, D., Dickinson, J., & Undre, N. (2012). Tacrolimus pharmacokinetics of once- versus twice-daily formulations in de novo kidney transplantation : a substudy of a randomized phase III trial. Therapeutic Drug Monitoring, 34(2), 143-147. https://doi.org/10.1097/FTD.0b013e31824d1620 (Original work published 2012)