Background: The calcineurin inhibitor tacrolimus (Tac) is an essential part from the standard immunosuppressive regimen after kidney transplantation (RTx). However, clinical control over Tac therapy can be tough due to its narrow therapeutic window and since many factors hinder its metabolic process. Therefore, therapeutic drug monitoring can be used to regulate the dosage.

Method: Lately, we could classify patients receiving tacrolimus into two major metabolic process groups by simple calculation from the C/D ratio (expressed because the bloodstream concentration normalized through the dose).

Results: We demonstrated the C/D ratio is considerably connected using the (kidney) results of recipients after kidney and liver transplantation.

Conclusion: These bits of information are intriguing and highly relevant to transplant physicians and physicians thinking about immunosuppressive therapy. We therefore review current condition from the art facets of tacrolimus pharmacokinetics including genetics or different tacrolimus formulations (two times-daily immediate-release tacrolimus capsules, once-daily extended- release tacrolimus capsules novel once-daily tacrolimus tablets) as well as their possible clinical impact including practical factors for clinicians.