Background: There is a correlation between cyclosporine (CsA) pharmacokinetics (PK) and pharmacodynamics (PD), especially 2 hours after drug administration.
Aim: To evaluate the relationship between CsA PK and PD profiles in two groups of stable renal transplant patients treated with CsA alone or CsA plus mycophenolate mofetil (CsA+MMF), so as to define the best target for C2 and clarify the impact of concomitant immunosuppression.
Methods: Thirty-eight stable renal transplant recipients were treated with CsA (n=20) or CsA+MMF (n=18). Twelve nontreated normal healthy controls (NHC) were also included. Calcineurin activity (CNa), IL-2 production, and CsA levels were measured at 0 and 2 hours postdose.
Results: There were no significant differences in median CsA C2 values and CNa between the CsA alone and the CsA+MMF groups (388 microg/L and 497.5 microg/L and CNa 2h; 3.92% alkaline phosphatase [AP]; 3.94% AP, respectively). In vitro production of IL-2 was significantly lower in the CsA+MMF group than in the CsA group (median IL-2 2h: 280.52 ng/L, 169.48 ng/L, P<.001). The correlations (r) between C2 and CNa 2h were: CsA r=0.74; CsA+MMF r=0.84 (P<.001 in both cases).
Conclusions: In stable renal transplant patients, median CsA C2 values below 500 microg/L were associated with inhibition of CNa and IL-2 synthesis. CNa and IL-2 production may be good biological markers of CsA immunosuppression. The measurement of CNa depends mainly on CsA concentration, whereas in vitro IL-2 production reflects the effect of both CsA and MMF. Further studies are necessary to define the optimal C2 target concentration and the possible impact of concomitant immunosuppression.