PLASMA-CONCENTRATIONS OF FREE AND CONJUGATED SILYBIN AFTER ORAL INTAKE OF A SILYBIN-PHOSPHATIDYLCHOLINE COMPLEX (SILIPIDE) IN HEALTHY-VOLUNTEERS

The plasma concentrations of free (unconjugated) and conjugated silybi n after intake of a single oral dose of a lipophilic silybin-phospatid ylcholine complex (silipide, 80 mg expressed as silybin equivalents) w ere evaluated in 12 healthy volunteers by using a sensitive and specif ic HPLC method. Free silybin concentrations reached a peak of 141+/-31 ng/ml (mean+/-SEM) at 2.4 hours after dosing and declined thereafter with a half-life of about 2 hours. Peak concentrations of conjugated s ilybin were greater (255+/-35 ng/ml) and occurred at a later time (abo ut 3.8 hours). The elimination of conjugated drug tended to be slower than that of foe drug. AUC values for conjugated sylibin were about th ree-fold greater than those of free drug. It is concluded that after o ral intake of silipide, silybin undergoes extensive conversion to conj ugated derivative(s) which are retained in the circulation at relative ly large concentrations.