tacrolimus and AIDS-Associated-Nephropathy

Ritonavir is an extremely strong inhibitor of P450 cytochrome 3A, which is the main metabolizing enzyme of tacrolimus. Subsequently, the pharmacokinetics of tacrolimus are affected to a large extend by the coadministration of ritonavir in HIV-infected transplant recipients. Therefore, to prevent overexposure directly posttransplantation in HIV-infected patients on ritonavir-containing cART, the predictive value of a pretransplantation pharmacokinetic curve of tacrolimus was explored.. A pretransplantation pharmacokinetic model of tacrolimus in these patients was developed, and a posttransplantation dosing advice was established for each individual patient. The pharmacokinetic population parameters were compared with HIV-negative patients, and predictive value of the pretransplantation curves was assessed in patients after the transplantation procedure.. No significant difference was found between the model-predicted and actual posttransplantation 24 h-tacrolimus levels (14.6 vs. 17.8 ng/mL, P=0.19). As the simulated pharmacokinetic curves lacked an absorption peak every 12 h, the mean 12 h-AUC was approximately 40 % lower compared with AUC's reported in HIV-negative recipients, when similar trough levels were targeted.. In conclusion, pretransplantation curves of tacrolimus seem a promising tool to prevent overexposure directly posttransplantation in patients on ritonavir-containing cART and raising trough levels to achieve an exposure equivalent to HIV-negative recipients is suggested.

Topics: Adult; AIDS-Associated Nephropathy; Area Under Curve; Biotransformation; Computer Simulation; Cytochrome P-450 CYP3A; Cytochrome P-450 CYP3A Inhibitors; Drug Interactions; Drug Monitoring; Enzyme Inhibitors; HIV Infections; HIV Protease Inhibitors; Humans; Immunosuppressive Agents; Kidney Failure, Chronic; Kidney Transplantation; Male; Middle Aged; Models, Biological; Pilot Projects; Ritonavir; Tacrolimus