Pharmacokinetics of a new microemulsion formulation of cyclosporin A (Neoral) in young patients after renal transplantation

Pharmacokinetics of the new galenic formulation of cyclosporin A, Neoral, (Sandoz) was examined in 12 stable young patients after renal transplantation. Six of these patients were tested before and 4 weeks after switching from the standard formulation Sandimmun to Neoral. No significant changes were observed in trough levels, tmax, Cmax, and AUC0–12h, but the absorption rate constant (Ka) increased (P= 0.03). Glomerular filtration rate, as assessed by insulin clearance, increased by more than 10 % in three patients and decreased in two, and was usually associated with a respective drop and rise in Cmax and AUCO0–12h of cyclosporin A. The large inter individual variability in the response to the conversion to the new formulation points to a need for close monitoring of cyclosporin A trough levels and renal function after switching from Sandimmun to Neoral in this age group in order to avoid nephrotoxicity.