Different influences on tacrolimus pharmacokinetics by coadministrations of zhi ke and zhi shi in rats

Abstract

Tacrolimus, an immunosuppressant with narrow therapeutic window, has been used widely in transplant patients. Grapefruit juice and pomelo have been reported to increase the blood levels of tacrolimus. Zhi Ke and Zhi Shi, the ripe peels and unripe fruits of Citrus aurantium which is chemotaxonomically related to grapefruit and pomelo, are in wide use in clinical Chinese medicine. To investigate the possible interaction of these two Citrus herbs with tacrolimus, male Sprague-Dawley rats were orally given tacrolimus (1.5 mg/kg) with and without Zhi Ke and Zhi Shi decoctions in a cross-over design. Blood samples were withdrawn via cardiopuncture at specific time and quantitated by a microparticle enzyme immunoassay. In addition, to explore the mechanism of interaction, LS 180 cell line was used for the transport study of rhodamine 123, a typical substrate of P-glycoprotein (P-gp). The results showed that Zhi Shi significantly decreased the C(max) and AUC(0-t) of tacrolimus by 72.4% and 72.0%, respectively, whereas Zhi Ke did not affect tacrolimus pharmacokinetics. LS 180 cell line study indicated that Zhi Shi increased the efflux activity of P-gp, enabling us to explain the decreased oral bioavailability of tacrolimus caused by Zhi Shi. Hence, we suggest that Zhi Shi be contraindicated for transplant patients treated with tacrolimus to reduce the risk of allograft rejection.

Figure 1

Crude drugs of Zhi Ke (a) and Zhi Shi (b).

Figure 2

Mean (±S.D.) blood concentration-time profiles of tacrolimus after oral administration of tacrolimus alone (1.5 mg/kg) (°) and coadministrations with 2 g/kg of Zhi Ke (●) and Zhi Shi (▾) decoctions.

Figure 3

Effects of Zhi Shi (mg/mL) and verapamil (V, 200 μM) on the accumulation of rhodamine 123 in LS 180 cells. Data expressed as mean ± S.D. *P < .05, **P < .01, ***P < .001.

Figure 4

Illustration of the inhibition of Zhi Shi on tacrolimus (TAC) absorption through activating the efflux function of P-gp on the cell membrane of enterocytes. TAC-M: TAC metabolites.