St. John’s Wort Lowers Plasma Levels of Many Drugs
This issue has gained a surprising amount of press since it came out. A few things to consider here. First, St. John’s Wort has been found to induce (speed up) the cytochrome P450 enzyme system which is required for detoxification. Many times in natural medicine this is a good thing…it’s just that with concommittent use of pharmaceutical drugs (almost all of which the body views as a toxin and tries to get rid off) will clear the drug out of the body quicker. Second, in none of the articles highlighting this facet of Hypericin have I seen a note to the effect that many (if not all..) pharmaceutical drugs used for psychological issues ALSO effect cytochrome P450-some induced and some repressed.
(article) St. John’s wort, through its induction of the enzyme cytochrome P450-3A4, can lead to markedly lower plasma levels of prescribed medications, reported Dr. George K. Dresser at the annual meeting here of the American Society for Clinical Pharmacology and Therapeutics. Dr. Dresser, of the University of Western Ontario, in London, and associates administered midazolam, a cytochrome P450-3A4-specific substrate, to 10 healthy volunteers before and after a 12-day treatment with St. John’s wort 900 mg/day. They found that the herbal product decreased blood levels of orally administered midazolam by 60%. Dr. Dresser pointed out that midazolam is only one of many drugs metabolized by the cytochrome P450-3A4 enzyme. “You can expect that for as many as half of the drugs in common use, lower levels would result when they’re taken with St. John’s wort,” Dr. Dresser told Reuters Health. Dr. Dresser recommends that physicians include in their patient histories the use of herbal products, particularly St. John’s wort. “If you have a patient taking St. John’s wort in whom you have titrated up the dose of a drug, and then that patient stops taking the St. John’s wort, that can be dangerous,” he said. In such an instance, blood levels of the drug could increase substantially. “Also,” he added, “if you have a patient taking a drug like cyclosporin, where it’s absolutely critical that they get the drug into their system, and this patient starts taking St. John’s wort, that can be equally or more dangerous as the level of the drug falls.” Dr. Dresser emphasized that “changes in St. John’s wort use in patients needs to be carefully documented.”