Impact of Cyclosporin A Pharmacokinetics on the Presence of Side Effects in Pediatric Renal Transplantation

Cyclosporin A (CsA) is a potent immunosuppressant that has many side effects, including hypertrichosis, gingival hyperplasia, and tremor. To evaluate whether there is a relationship between the CsA-pharmacokinetics (PK) and these side effects, their presence and intensity were observed in 46 renal transplanted children/adolescents during two regular visits, and the occurrence of the side effects was correlated with CsA-PK. CsA doses had been unchanged for at least 6 mo. CsA blood concentrations were measured at time 0, and 1, 2, and 4 h after the CsA morning dose. An abbreviated area under the curve (AUC) was calculated using C0, C2, and C4. Hypertrichosis positively correlated with C2, C4, C max , and AUC. An AUC ≥ 4158 ng/ml per h was the best predictor for the presence of hypertrichosis. Tremor was also positively correlated with C2, C max , and AUC. A C max ≥ 878 ng/ml was the best predictor for the appearance of tremor. These values of C max and AUC are within the therapeutic range of CsA as demonstrated by the studies of calcineurin inhibition by CsA. Gingival hyperplasia was not associated with any of the CsA-PK studied parameters. However, it was associated with the concomitant use of nifedipine. These data show that there is a correlation between the CsA side effects and its pharmacokinetics and that it is possible to decrease the incidence and intensity of such side effects by monitoring the CsA-PK parameters, providing they are under or at the proposed cutoff levels. Nifedipine should also be avoided to reduce the presence of gingival hyperplasia.