A six-hour extrapolated sampling strategy for monitoring mycophenolic acid in renal transplant patients in the Indian subcontinent.

Background: Therapeutic drug monitoring for mycophenolic acid (MPA) is increasingly being advocated. The present therapeutic range relates to the 12-hour area under the serum concentration time profile (AUC). However, this is a cumbersome, tedious, cost restricting procedure. Is it possible to reduce this sampling period? Aim: To compare the AUC from a reduced sampling strategy with the full 12-hour profile for MPA. Settings and Design: Clinical Pharmacology Unit of a tertiary care hospital in South India. Retrospective, paired data. Materials and Methods: Thirty-four 12-hour profiles from post-renal transplant patients on Cellcept® were evaluated. Profiles were grouped according to steroid and immunosuppressant co-medication and the time after transplant. MPA was estimated by high performance liquid chromatography with UV detection. From the 12-hour profiles the AUC up to only six hours was calculated by the trapezoidal rule and a correction factor applied. These two AUCs were then compared. Statistical Analysis: Linear regression, intra-class correlations (ICC) and a two-tailed paired t-test were applied to the data. Results: Comparing the 12-hour AUC with the paired 6-hour extrapolated AUC, the ICC and linear regression (r²) were very good for all three groups. No statistical difference was found by a two-tailed paired t-test. No bias was seen with a Bland Altman plot or by calculation. Conclusion: For patients on Cellcept® with prednisolone ± cyclosporine the 6-hour corrected is an accurate measure of the full 12-hour AUC. [ABSTRACT FROM AUTHOR]