title: Neoral monitoring by simplified sparse sampling area under the concentration-time curve: its relationship to acute rejection and cyclosporine nephrotoxicity early after kidney transplantation.
abstract: BACKGROUND
  Cyclosporine (CsA) dosing is traditionally based on trough blood levels (C0) rather than area under the concentration-time curve (AUC), although AUC correlates better with posttransplantation clinical events. For Neoral, AUC based on limited sampling correlates closely with full 12-hr AUC. The purpose of our study was to correlate C0 with AUC based on CsA levels at 0, 1, 2, 3, and 4 hr after dose (PK0-4) and to compare this AUC with C0 in predicting acute rejection (AR) and acute cyclosporine nephrotoxicity (CsANT) in de novo first kidney transplant patients.
  
  
  METHODS
  PK0-4 was done 2-4 days after starting Neoral for 156 patients. All received CsA-based triple-drug immunosuppression without antibody induction. AUC was calculated as projected 12-hr (AUC0-12) and actual 4-hr (AUC0-4) from the PK0-4 using the parallel trapezoid rule. Neoral dosing was based on C0 not AUC. AUC was retrospectively compared with C0 as a predictor of AR and CsANT during the first 90 days.
  
  
  RESULTS
  C0 correlated poorly with AUC0-12 and AUC0-4 (r=0.61 and r=0.42). C0 (mean+/-SEM) levels were not significantly different in 34 patients with and 109 without AR (293+/-21 vs. 294+/-11 microg/L, P=0.95). AUC0-12 and AUC0-4 were significantly lower in patients with than without AR (AUC0-12 9090+/-598 vs. 10608+/-336 microg x h/L, P=0.01; AUC0-4 3934+/-306 vs. 4802+/-166 microg.h/L, P=0.006). In stepwise regression analysis only AUC0-12 or AUC0-4 (P=0.03/P=0.02) and delayed graft function (P=0.007) predicted AR. AUC0-12, AUC0-4, and C0 were all significantly higher in patients with CsANT than without CsANT (AUC0-12 11746+/-650 vs. 10023+/-301 microg x h/L, P=0.01; AUC0-4 5270+/-358 vs. 4474+/-150 microg x h/L, P=0.01; C0 343+/-18 vs. 287+/-10 microg/L, P=0.01), but in stepwise regression analysis C0 was not an independent predictor of CsANT. Patients with AUC0-12 in the range of 9500 to 11500 microg x h/L or AUC0-4 between 4400 and 5500 microg x h/L had the lowest incidence of AR (13% and 7%, respectively) without significantly higher risk for CsANT.
  
  
  CONCLUSIONS
  C0 correlates poorly with AUC based on PK0-4. Early AUC based on PK0-4 is more closely associated with AR and CsANT than is C0. Our data suggest that a target AUC0-12 of 9500-11500 or AUC0-4 of 4400-5500 microg x h/L may provide optimal Neoral immunosuppression.
authors.affiliation: Department of Urology, Queen Elizabeth II Health Sciences Centre, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: K
authors.initials: K
authors.lastname: Mahalati
authors.forename: P
authors.initials: P
authors.lastname: Belitsky
authors.forename: I
authors.initials: I
authors.lastname: Sketris
authors.forename: K
authors.initials: K
authors.lastname: West
authors.forename: R
authors.initials: R
authors.lastname: Panek
mesh_terms: D000208:Acute Disease; D000328:Adult; D019540:Area Under Curve; D001682:Biological Availability; D016572:Cyclosporine / Q000008:administration & dosage* / Q000493:pharmacokinetics* / Q000627:therapeutic use / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D016903:Drug Monitoring / Q000379:methods*; D005260:Female; D006084:Graft Rejection / Q000517:prevention & control; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D007674:Kidney Diseases / Q000139:chemically induced; D016030:Kidney Transplantation / Q000276:immunology; D008297:Male; D008875:Middle Aged; D013997:Time Factors
chemical_list: D007166:Immunosuppressive Agents; D016572:Cyclosporine