Background: Tacrolimus (Tac) is widely used to prevent allograft rejection after liver transplantation. We found that the concentration of Tac in blood was significantly increased in liver transplant patients who were receiving Schisandra sphenanthera extract (SchE). The objective of this study was to determine the effect of SchE on the concentration of Tac in the blood of liver transplant patients.
Materials and methods: Patients were initially administered Tac (first phase) and then SchE was provided (second phase). During the first phase of treatment, 46 patients received the same oral dose of Tac. In the second phase of treatment, 21 patients (Group A) received the same dose of Tac and 25 patients (Group B) received a lower dose of Tac. The concentration of Tac in the blood and the biochemical indices of liver function, as well as symptoms of Tac-related toxicity, were determined, and 14 patients were selected for a pharmacokinetic study.
Results: After co-administration of Tac and SchE, the average increase in the mean concentration of Tac in the blood was 339% and 262% in Groups A and B, respectively. The liver function indices were decreased significantly (p < 0.01); whereas the average increase of Cmax, AUC0-12 and AUMC0-12 of Tac was 183%, 212% and 227%, respectively. Tac-associated side-effects, such as diarrhoea and agitation, decreased significantly in all patients, but the incidence of other side-effects did not change significantly.
Conclusions: SchE markedly increased the concentration of Tac in the blood of liver transplant patients, improved liver function and reduced the incidence of Tac-associated side-effects.