Comparison of mycophenolic acid concentrations determined by a new PETINIA assay on the dimension EXL analyzer and a HPLC-UV method.

OBJECTIVE

Mycophenolic acid requires routine therapeutic drug monitoring. We evaluated the suitability of a new PETINIA (particle enhanced turbidimetric inhibition immunoassay) assay on the Dimension EXL analyzer for monitoring of mycophenolic acid by comparing values obtained by this assay with a HPLC-UV method.

DESIGN AND METHODS

Mycophenolic acid concentrations determined in sera of 60 organ transplant recipients using high performance liquid chromatography combined with ultraviolet detection (HPLC-UV, reference method) and the new immunoassay on the Dimension RxL analyzer.

RESULTS

The within and between run precision of the new PETINIA assay was <10%. The assay was linear for a mycophenolic acid concentration up to 30μg/mL. When mycophenolic acid concentrations in 60 transplant recipients obtained by the HPLC-UV (x-axis) method were compared with corresponding values obtained by the PETINIA assay (y-axis), the following regression equation was obtained: y=1.1204 x+0.0881 (r=0.983, n=60).

CONCLUSIONS

If PETINIA assay is used for therapeutic drug monitoring of mycophenolic acid, caution must be exercised in interpreting serum mycophenolic acid level due to observed positive bias.