Interaction of Hypericum perforatum (St. John's wort) with cyclosporin A metabolism in a patient after liver transplantation

Immunosuppressive therapy in patients after Fiver transplantation requires careful monitoring of blood levels for immunosuppressive agents such as cyc losporin A, A variety of drugs are capable of interfering with the metaboli sm of cyclosporin A. We observed a 63-year-old patient who received a liver allograft for cryptogenic liver cirrhosis in 1998, This patient developed severe acute rejection 14 months after transplantation which was associated with a sudden drop in cyclosporin A levels, Two weeks previously, he had s tarted taking the herbal drug Hypericum perforatum (2x900 mg/day) for incre asing episodes of depression. The cyclosporin A dosage later had to be doub led, which caused some side effects. Finally, an assessment of oral cyclosp orin A resorption suggested an enhanced cyclosporin A metabolism. Hypericum perforatum was stopped, Both cyclosporin A dosage and blood levels immedia tely returned to normal, The liver function recovered completely. In conclu sion, this observation is a previously undescribed drug interaction of a wi dely used herbal drug (Hypericum perforatum, i,e, St, John's wort) in a pat ient after liver transplantation.