Assessment of the Bioequivalence of a Generic Cyclosporine A by a Randomized Controlled Trial in Stable Renal Recipients

Abstract

BACKGROUND: The aim of this study was to determine the bioequivalence of Cysporin, a generic cyclosporine A, compared with Neoral in stable renal transplant recipients. METHODS: Study design consisted of an open label, two-way crossover, randomized controlled trial of Cysporin versus Neoral in stable renal transplant recipients. In all, 33 patients were enrolled; 31 were randomized and 28 were evaluable. AUCs(0-12) were done on day 14 and 28; C(0) and C(2) were done on days 0, 7, 21 and 35. Dose conversion was 1:1. Outcome measures for serum cyclosporin A concentrations expressed as the mean+/-SD were AUC(0-12) (microg x hr/L), C(max) (microg/L), C(2) (microg/L), T(max) (hr) and T(1/2) (hr). Mean and 90% CI of the ratio Cysporin/Neoral of log-transformed data were calculated using a general linear model. RESULTS: The main pharmacokinetic features were: AUC(0-12): Cysporin 3495+/-1319, Neoral 3853+/-1378 (P<0.05); C(max): Cysporin 755+/-301, Neoral 881+/-368 (P<0.05); C(2): Cysporin 613+/-235, Neoral 672+/-255 (P>0.05); T(max): Cysporin 1.9+/-0.8, Neoral 1.4+/-0.6 (P<0.005); and T1/2: Cysporin 8.8+/-4.3, Neoral 8.7+/-6.2 (P>0.05). Estimated ratios of Cysporin/Neoral were: AUC 0.93 (90% CI 0.88-0.98; P<0.05); C(max) 0.88 (90% CI 0.80-0.97; P<0.05); and T(max) 1.32 (90% CI 1.14-1.53; P<0.005). CONCLUSIONS: Both the extent and rate of absorption of Cysporin are significantly less than those of Neoral. The 90% CI for the ratios of Cysporin/Neoral for AUC and C(max) lie within 0.80-1.25. Hence in this clinical context Cysporin is pharmacologically bioequivalent with Neoral. This study illustrates the importance of testing bioequivalence of generic cyclosporine A products in transplant recipients not healthy volunteers.