Kidney function after 1:1 conversion to the cyclosporine microemulsion formulation in children with liver allografts

One-to-one (mg:mg) conversion from the conventional to the microemulsion formulation of cyclosporine (CsA) is advocated as a simple way to use the new therapeutic regimen. However, the potentially harmful effects of the conversion on kidney function in nonrenal transplant recipients are poorly known.

Renal effects of the conversion were prospectively investigated in 22 pediatric liver transplant recipients (mean age, 8.4 years; mean time from transplantation, 3.2 years). Patients were followed for 12 months. Pharmacokinetic studies were performed at baseline and 5 days and 6 and 12 months after conversion.

Peak concentration, minimum concentration, average steady state concentration, and area under the concentration-versus-time curve increased by 60-130% after conversion. Graft losses, progressive deterioration of graft function, and acute rejection episodes did not occur. The mean glomerular filtration rate (GFR) was 103 ml/min/1.73 m2 at baseline and 100 ml/min/1.73 m2 after 12 months. However, 6 of the 22 patients showed at least a 15% (range, 16-38%) decrease in GFR between baseline and 6 months (P<0.01). They had a significantly higher increase in average steady state concentration between baseline and 6 months than the six patients with the best outcome in GFR during the same time period (164 ng/ml vs. 53 ng/ml, P<0.05). At this point (6 months), target CsA trough levels were reduced by 20-30%, while the mean area under the concentration-versus-time curve remained above that obtained at baseline. The GFR of three of the six patients subsequently improved.

One-to-one conversion can be performed safely in liver transplant recipients if strict follow-up is feasible.