Effects of curcumin on cyclosporine-induced cholestasis and hypercholesterolemia and on cyclosporine metabolism in the rat.

Former studies have shown that curcumin, which can be extracted from different Curcuma species, is able to stimulate bile flow and to reduce hypercholesterolemia. We investigated in a subchronic bile fistula model the ability of curcumin to reduce cyclosporine-induced cholestasis and hypercholesterolemia. Male Wistar rats were daily treated with curcumin (100 mg/kg p. o.), cyclosporine (10 mg/kg i. p.), and a combination of curcumin with cyclosporine. After two weeks a bile fistula was installed into the rats to measure bile flow and biliary excretion of bile salts, cholesterol, bilirubin, cyclosporine and its main metabolites. Blood was taken to determine the concentration of these parameters in serum or blood. Cyclosporine reduced bile flow (-14 %) and biliary excretion of bile salts (-10 %) and cholesterol (-61 %). On the other hand, cyclosporine increased serum concentrations of cholesterol and triglycerides by 32 % and 82 %, respectively. Sole administration of curcumin led to a slight decrease of bile flow (-7 %) and biliary bile salt excretion (-12 %), but showed no effect on biliary excretion of cholesterol and serum lipid concentration. When curcumin was given simultaneously with cyclosporine, the cyclosporine-induced cholestasis was enhanced but the cyclosporine-induced hyperlipidemia was not affected. Neither the biliary excretion nor the blood concentration of cyclosporine was influenced by curcumin. The blood concentration of the main cyclosporine metabolites, however, was lowered by half while their biliary excretion was strongly increased by curcumin. From these results we conclude that curcumin is not able to prevent cyclosporine-induced cholestasis and hyperlipidemia after prolonged administration in bile fistula rats.

Sirolimus/cyclosporine/tacrolimus interactions on bile flow and biliary excretion of immunosuppressants in a subchronic bile fistula rat model.

The new immunosuppressive agent sirolimus generally is combined in transplant patients with cyclosporine and tacrolimus which both exhibit cholestatic effects. Nothing is known about possible cholestatic effects of these combinations which might be important for biliary excretion of endogenous compounds as well as of immunosuppressants. Rats were daily treated with sirolimus (1 mg kg(-1) p.o.), cyclosporine (10 mg kg(-1) i.p.), tacrolimus (1 mg kg(-1) i.p.), or a combination of sirolimus with cyclosporine or tacrolimus. After 14 days a bile fistula was installed to investigate the effects of the immunosuppressants and their combinations on bile flow and on biliary excretion of bile salts, cholesterol, and immunosuppressants. Cyclosporine as well as tacrolimus reduced bile flow (-22%; -18%), biliary excretion of bile salts (-15%;-36%) and cholesterol (-15%; -47%). Sirolimus decreased bile flow by 10%, but had no effect on cholesterol or bile salt excretion. Combination of sirolimus/cyclosporine decreased bile flow and biliary bile salt excretion to the same extent as cyclosporine alone, but led to a 2 fold increase of biliary cholesterol excretion. Combination of sirolimus/tacrolimus reduced bile flow only by 7.5% and did not change biliary bile salt and cholesterol excretion. Sirolimus enhanced blood concentrations of cyclosporine (+40%) and tacrolimus (+57%). Sirolimus blood concentration was increased by cyclosporine (+400%), but was not affected by tacrolimus. We conclude that a combination of sirolimus/tacrolimus could be the better alternative to the cotreatment of sirolimus/cyclosporine in cholestatic patients and in those facing difficulties in reaching therapeutic ranges of sirolimus blood concentration.