C2 is an age-independent parameter for optimal cyclosporine exposure in long-term kidney transplant recipients

The argument for therapeutic drug monitoring (TDM) of cyclosporine (Cya) has been discussed for the last two decades. So far, a generalized consensus has been reached for TDM of Cya microemulsion in adult transplant recipients, being Cya blood levels obtained 2 hours after the administration (C2), the most reliable in reflecting the overall Cya exposure. However, clear guidelines are not available for the pediatric population because of the distinct metabolism of the drug in this patient population. Therefore, adult data do not necessarily apply to children. In this retrospective analysis, the authors sought to define a universal parameter for pharmacokinetic clinical monitoring of Cya in long-term kidney transplant recipients, regardless of their age. Lower C2 levels were observed in all patients, adult and pediatric, who eventually developed chronic allograft dysfunction (CRAD) compared with patients who maintained stable kidney function throughout the entire follow-up (pediatric CRAD, 933 +/- 455 ng/mL; vs Stable, 1236 +/- 347 ng/mL, P = .0001; and adult CRAD, 781 +/- 518 ng/mL; vs Stable, 1088 +/- 452 ng/mL, P = .009). On the other hand, the risk of Cya underexposure was not highlighted by trough level monitoring (C0) because all patients have been maintained steadily on therapeutical C0 levels for the entire follow-up. In conclusion, for Cya maintenance therapy, C2 appears to be a superior strategy to C0 monitoring in both adult and pediatric kidney transplant recipients.