Sublingual Tacrolimus in Liver Transplantation: A Valid Option?

Background Oral tacrolimus (Tac) is currently the pillar of maintenance immunosuppression after solid organ transplantation. Recent studies proposed sublingual (SL) administration as an alternative; however, data regarding its use in adult liver transplant (LT) recipients are limited. Methods Three LT recipients were included. Two (patients 1 and 2) were transitioned from oral to SL Tac owing to persistently erratic serum concentrations and 1 (patient 3) because of severe oral intolerance. SL Tac was started in a 1:2 dose-conversion rate. Results All patients tolerated the SL Tac well without any side effects requiring dose reduction or discontinuation. In patients 1 and 2, the therapeutic trough concentrations improved significantly after switching to SL Tac: 20% (10/50) on oral Tac to 50% (7/14) on SL Tac in patient 1 (P =.04), and from 0% (0/15) oral Tac vs 40% (4/10) on SL Tac in patient 2 (P =.02). Patient 2, who had consistently subtherapeutic trough levels on oral Tac (mean trough of 2.6 ± 0.7 ng/mL), achieved a stable therapeutic level on SL Tac (mean trough 8.1 ± 2.7 ng/mL; P <.001). In patients 1 and 3, the mean trough levels remained unchanged: 5.1 ± 1.9 ng/mL on oral Tac versus 5.3 ± 1.6 ng/mL on SL Tac (P =.76), and 4.3 ± 1.3 ng/mL on oral Tac versus 4.2 ± 1.9 ng/mL on SL Tac (P =.76), respectively. Conclusions Oral administration of Tac is the criterion standard route for drug delivery; however SL administration should be considered as a safe alternative when the oral method is not an option.