Hypericin drug interactions

This herbal product has the most data available to support its usefulness as an antidepressant. Nevertheless, only minimal information is available about its pharmacology and its relative risk-benefit ratio. At least seven different biologically active chemicals have been isolated from crude extracts of hypericum. Several are ubiquitous in the plant kingdom. The exceptions are hypericin and pseudohypericin, which have been assumed to be responsible for any antidepressant activity of this product. Nevertheless, there is the potential for one or more of these seven compounds and their metabolites to mediate desired or undesired effects, particularly when used in combination with other medications (i.e., herb-drug interactions). 

Women use herbal and dietary supplements at higher rates than men do. This rise in use of alternative therapies places women at increased risk of significant drug interactions, specifically drug-herb and drug-nutrient interactions (83 9). For instance, St. John s wort, a popular antidepressant, contains at least seven groups of chemical compounds. These include naphthodianthrons (hypericin and pseudohypericin), flavonoids (quercetin, hyperoside, and rutin). 

Two molecular mechanisms for the interactions have been established. First, both hypericin and hy-perforin, two of the pharmacologically active constituents of the herb, cause induction of the enzyme CYP3A4 which is responsible for much of the metabolism of many commonly used drugs. Giving SJW to patients also taking the immunosuppressant, cyclosporine, which is metabolized primarily by CYP3A4, has led to near-rejection of transplanted organs as cyclosporine plasma concentrations fell due to increased metabolism. The same mechanism has led to reduced efficacy of indinavir in patients... 

Miskovsky P. Hypericin - a new antiviral and antitumor photo- 45. sensitizer mechanism of action and interaction with biological macromolecules. Curr. Drug Targets 2002 3 55-84. 

A commoniy reported drug-dietary suppiement interaction is between St. John s Wort and FiiV protease inhibitors, ieading to drug resistance and treatment faiiure. St. John s wort is a popuiar dietary suppiement often used for depression. Of the two substances found in St. John s wort, hypericin and hyperforin, hyperforin appears to be the main constituent, with in vitro seieotive serotonin reuptake inhibitor (SSRi) activity (see Chapter 21). Hyperforin aiso appears to be the more potent inducer of CYP3A enzymes based on in vitro and in vivo studies. 

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