Influence of Pantoprazole on the Bioavailability of MMF and EC-MPS

Inclusion Criteria: * patients \>18 years old * patients who are on stable immunosuppressive therapy for at least one month with ciclosporin, EC-MPS or MMF +/- corticosteroids * renal transplantation, at least 6 months prior study inclusion * suitable and willing to switch treatment according to the study plan * women of childbearing potential must have a negative serum pregnancy test before study start and effective contraception must be used (method with PEARL index \<1%) Exclusion Criteria: * patients with renal function \<30ml/min (estimated by Cockcroft Gault formula) * patients who are not on stable treatment with enzyme inductors or enzyme inhibitors for \<1 month before study entry * patients who take medication which is known for interfering with MPA absorption for \<1 month before study entry * known anamnestic hypersensitivity to one of the investigational products or drugs with similar chemical structure and to other components of the investigational products, respectively * patients on treatment with clopidogrel * acute rejection \< 1 month before study inclusion * patients who are HIV positive, hepatitis C virus (HCV) positive, HBsAg positive * patients with gastrointestinal disorders which could affect resorption * pregnancy and/or lactation * drug or alcohol abuse in patient's history * patients with history of psychological illness or condition, which might interfere with the ability to understand the requirements, consequences, possible outcome of the study and patients who are not willing to give valid informed consent * patients with insufficient co-operation with the clinical investigator (e.g. suspicion of non-compliance)