From therapeutic drug monitoring to drug management : IMPDH activity as novel surrogate marker for dose adjustment of Mycophenolate in immunosuppressive therapy

Abstract EN

Background : Mycophenolic acid is a well established inhibitor of inosine-monophosphate-dehydrogenase (IMPDH) in immunosuppressive therapy.

Adverse side effects require dose reduction in more than half of the patients, increasing the risk for acute rejection.

Unlike for other immunosuppressants, measuring the trough level shows no relevant correlation to the risk of graft loss.

Instead, we determined the residual IMPDH activity, aiming on suggesting trusted intervals for drug management in the context of dose-reduction.

Materials and Methods: IMPDH activity (pmol/s per pmol AMP) was measured in 276 stable patients after renal transplantation.

Results : A mean overall residual activity of 38.9 ± 45.9 pmol/s pmol AMP (median = 28 pmol/s pmol AMP) was derived from 2505 individual measurements; the 10th percentile equaled 5 pmol/s pmol AMP, the 90th percentile 78 pmol/s pmol AMP.

Conclusion: Measurement of IMPDH activity in renal transplantation patients adds valuable information on the degree of immunosuppression