Systematic conversion to generic tacrolimus in stable kidney transplant recipients

BACKGROUND Tacrolimus (Prograf®) is a key drug in the immunosuppressive treatment of renal transplant patients. Since the expiration of the patent for Prograf®, generic preparations have been approved in Europe as bioequivalence has been shown in healthy volunteers. However, few studies have investigated whether patients can be successfully converted from Prograf® to generic tacrolimus. Tacrolimus drug costs are by far the largest single item in the total drug expenditure for patients with renal disease in the Stockholm area. Considerable reductions in drug costs could be achieved if generic tacrolimus were to be used. The aim of this quality assurance study was to evaluate whether a switch from Prograf® to generic tacrolimus (Tacrolimus Sandoz®) could be safely performed in renal transplant patients. It further aimed to investigate changes of renal function (measured in estimated glomerular filtration rate, eGFR), need for dose changes and to calculate potential drug cost savings as a result of the conversion. METHODS We planned to recruit at least 50 patients. Plasma creatinine levels and trough concentrations of tacrolimus were collected from patients with renal transplants at three occasions during treatment with Prograf® and three times after conversion to Tacrolimus Sandoz®. The eGFR was calculated before and after the conversion. RESULTS Sixty-three of 67 enrolled patients (69% males, age 28-80 years) are included in this analysis. The ratio of mean trough concentrations of tacrolimus after comparison with before conversion was 1.02 (90% confidence interval 0.95-1.09). Fourteen patients experienced a change in tacrolimus levels >20% compared with baseline, no patients changed >20% in eGFR. The drug cost saving per daily dose was 33.40 SEK (∼€3.60, -23%). CONCLUSIONS Stable kidney transplant patients treated with Prograf® can be converted to Tacrolimus Sandoz® if trough concentrations of tacrolimus and plasma creatinine levels are closely monitored. The conversion brought savings, despite costs for extra monitoring.