Cyclosporine (CyA) trough concentrations are poor predictors for acute rejection post-transplant. Patients were part of a randomized trial of basiliximab (n=70) vs. anti-thymocyte globulin (ATGAM) (n=65), both in combination with Neoral, mycophenolate mofetil, and steroids, undergoing first or second, cadaveric or live donor renal transplants. Whole blood samples were collected just before (C0) and at 2 h after CyA dosing on day 4 and at the end of weeks 1, 2, 4, and 8. The CyA was measured by fluorescence polarization immunoassay (TDx). Mean CyA C0 and C2 concentrations were calculated. Logistic regression analysis revealed that mean C2 level was the only predictor of acute rejection (P < or = 0.001). Higher mean C2 levels predicted lower rejection probabilities. Linear regression analysis revealed that higher mean C2 levels were not related to higher serum creatinine levels at either week 4 or 24 or to incidence of headache or tremor. The CyA C2 levels predict the frequency of rejection postrenal transplant. Target C2 levels are in the range of 1500 ng/dL.
and † Novartis Pharmaceuticals, East Hanover, New JerseyWith the recent focus of monitoring cyclosporine (CsA) therapy using measures of CsA absorption, it is important to understand published reports of diurnal variation in CsA exposure. In 10 renal transplant patients, CsA concentrations were measured 0, 1, 2, 3, and 4 h after both the morning and the evening doses and in a repeat session at least 1 wk later. Both area under the curve for the final 4 h after cyclosporine dose and cyclosporine concentrate 2 h after the cyclosporine dose were more than two-fold higher after the morning dose in both sessions. Because the morning levels were collected in a fasted condition and the evening ones in a fed condition, the study was extended to collect evening levels after fasting. The area under the curve for the final 4 h after cyclosporine dose and cyclosporine concentrate 2 h after the cyclosporine dose values observed now were comparable to the morning fasted values. That the large diurnal variation was due to variation in food consumption, as opposed to a biologic circadian rhythm affecting CsA absorption, has significant implications for therapeutic drug monitoring.
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