ZURICH, SWITZERLAND. Cardiologists at the Zurich University Hospital report two recent cases of acute heart transplant rejection probably caused by an interaction between the antidepressant St. John's wort and the immunosuppressive drugs used to prevent rejection. A 61-year-old heart transplant patient was diagnosed with acute cellular transplant rejection 11 months after a successful heart transplant. Three weeks prior to the diagnosis he had started self-medication with St. John's wort (300 mg three times daily) in order to treat a mild depression. His prescription drugs included cyclosporin (ciclosporin) 125 mg twice daily, azathioprine 100 mg daily, and low dose corticosteroids (7.5 mg daily). Blood analysis showed cyclosporin levels to be below the therapeutic range. Levels returned to normal after discontinuing the St. John's wort and there were no further episodes of rejection.
The second case involved a 63-year-old patient who had undergone a
successful heart transplant 20 months earlier. He was on a
similar drug regimen as the first case and had been prescribed St.
John's wort by his psychiatrist three weeks prior to the diagnosis
of acute transplant rejection. The episode was resolved by
discontinuing the treatment with St. John's wort. The
cardiologists conclude that St. John's wort reduced the blood
levels of the anti-rejection drug cyclosporin and attribute this
reaction to the fact that cyclosporin and St. John's wort are both
metabolized by the cytochrome P-450 complex.