Hypericin levels in human serum and interstitial skin blister fluid after oral single-dose and steady-state administration of Hypericum perforatum extract (St. John's wort)

The photodynamically active plant pigment hypericin, a characteristic metab olite of Hypericum perforatum (St. John's wort), is widely used as an antid epressant. When adm ministered orally, phototoxic symptoms may limit the th erapeutic use of hypericin-containing drugs. Here we describe the high-perf ormance liquid chromatographic (HPLC) detection of hypericin and semiquanti tative detection of pseudohypericin in human serum and skin blister fluid a fter oral single-dose (1 x 6 tablets) or steady-state (3 x 1 tablet/day, fo r 7 days) administration of the Hypericum extract LI 160 in healthy volunte ers (n = 12). Serum levels of hypericin and pseudohypericin were always sig nificantly higher than skin levels (p less than or equal to 0.01). After or al single-dose administration of Hypericum extract the mean serum level of total hypericin (hypericin + pseudohypericin) was 43 ng/ml and the mean ski n blister fluid level was 5.3 ng/ml. After steady-state administration the mean serum level of total hypericin was 12.5 ng/ml and the mean skin bliste r fluid level was 2.8 ng/ml. These skin levels are far below hypericin skin levels that a re estimated to be phototoxic (>100 ng/ml).