Jerry Cott, PhD
Research Pharmacologist,
Scientific Advisor to the Health Professions,
College Park, MD.
St. John's Wort (Hypericum perforatum; SJW) is a common roadside plant that has gained much popularity in Europe and the United States as an alternative to synthetic antidepressants. The market for SJW in 1998 was $330 million in Europe and $210 million in the U.S. Hypericum appears to be an effective antidepressant with an excellent safety profile (with the interaction caveat discussed here). The NIH has just completed a multi-centre study comparing the efficacy of SJW to sertraline and placebo for treating patients with moderate to severe depression. This study was completed in December 2000, and results should be available in the summer of 2001.
Although SJW has been shown to inhibit monoamine oxidase (MAO) in vitro, this effect has not been demonstrated in vivo, nor have there been any reported cases of MAOI-associated hypertensive crises in humans using SJW.1 Although SJW has been reported to inhibit uptake of serotonin, norepinephrine and dopamine in vitro,2 the concentrations required to attain these effects are quite high and the chance of a patient attaining equivalent blood concentrations is low. In fact, a recent study suggests that the uptake inhibition is only an artifact of the assay since, in contrast to other inhibitors, it does not bind to the serotonin uptake site but does deplete storage vesicles in a similar fashion to reserpine.
