Bioequivalence and Bioavailability Forum 11:37 CET

Dear EKY,

» According to available data that methylphenidate and its metabolites are distributed between plasma (57%) and erythrocytes (43%) in blood.

If I interpret correctly what you wrote, concentrations are comparable in plasma and erythrocytes. So hemolysis will not release massive amounts of the drug or metabolites in plasma, contrary to e.g. ciclosporine.

» Can the respective plasma concentrations from hemolysis samples be fallacious?

Yes, possibly, by other ways. If you are using LC-MS/MS, you may have differences in matrix effects in hemolysed samples, but you are supposed to check for this during method validation. If you are using HPLC/UV, you may get chromatographic interferences. Whatever the method, you may have problems with recovery, or with analyte stability (see for instance this paper).