Ácido micofenólico

The pharmacokinetics of the immunosuppressant mycophenolate mofetil (MMF) have been investigated in healthy volunteers and mainly in recipients of renal allografts [1]. Following oral administration,mycophenolate mofetil is rapidly and completely absorbed, and undergoes extensive presystemic de-esterification forming the active metabolite, mycophenolic acid (MPA), an antiproliferative agent thatacts by reversible and selective inhibition of type II inosine monophosphate dehydrogenase, a key enzyme in the de novo biosynthesis of purines [2].

Mycophenolate mofetil itself is notquantifiable in plasma after oral administration, but is measurable after intravenous infusion implying almost complete first pass de-esterification of the drug [3]. During intravenous infusion of mycophenolatemofetil 1.5g at a constant rate over 1 hour, a mean plateau concentration around 2.5 to 3 mg/L was rapidly reached. The mean plasma clearance of intravenous mycophenolate mofetil was in the range of8.5 to 11.6 L/min, values which exceed plasma cardiac output. Following termination of the mycophenolate mofetil infusion, rapid decline in the plasma concentration occurred; thalf could not beestimated, but the drug was not detected in plasma 10 minutes after the cessation of the infusion, indicating that the thalf was probably less than 2 minutes [1].

On the other hand, although the FDArecommends for BE studies measurement of the parent drug released from the dosage form, rather than the metabolite, nevertheless it excludes affirming “measurement of a metabolite may be preferred whenparent drug levels are too low to allow reliable analytical measurement in blood, plasma, or serum for an adequate length of time. We recommend that the metabolite data obtained from these studies besubject to a confidence interval approach for BE demonstration” [4].
Kindly find attached several references where MPA was used practically in all clinical/PK studies as the marker instead MMF....