Cytochrome P450 2D6 (CYP2D6) is a liver enzyme responsible for the metabolism of approximately 30% of all drugs.
Researchers at the University of Arkansas for Medical Sciences in Little Rock studied the effect of CYP2D6 on the metabolism of several herbal supplements and the risk of drug interactions. Continue reading CYP2D6-mediated herb-drug interactions
Researchers from the Russian Academy of Natural Sciences, in Moscow report that time-released tablets (Allicor) are more effective than regular garlic supplements (Kwai). Continue reading Treating hypertension with time-released garlic tablets
Thanks to a barrage of recent studies and conflicting media messages, consumers are confused about the benefits (if any) from vitamin E supplements.
Until all this is sorted out, remember, high doses of vitamin E increase the risk of bleeding.
Here’s what we know about that. Continue reading Vitamin E and the risk of bleeding
Researchers from Georgetown University in Washington, DC report that when taken short term, Echinacea purpurea products (roots and/or aerial parts) do not appear to be a risk to consumers. Continue reading Lack of drug interactions with echinacea
“No ibuprofen [Advil, Motrin, Nuprin, Medipren] dose adjustments appear warranted when the drug is administered orally with St. John’s wort,” according to this study by Dr. Edward Bell in an article published in The Annals of Pharmacotherapy. Continue reading St. John’s wort and ibuprofen pharmacokinetics
CYP3A4 is a member of the liver enzymes known as the cytochrome P450 mixed-function oxidase system. It’s one of the most important enzymes involved in the metabolism of drugs.
Researchers at the Norwegian University of Science and Technology in Trondheim evaluated several herbal remedies for their ability to inhibit CYP3A4. Continue reading CYP3A4 inhibition by herbals
Dr. Thomas Lenz from Creighton University, in Omaha, Nebraska reviewed the evidence. Continue reading Risks from exercise in people taking statins
In addition to interacting with midazolam (Versed for sedation and anxiety), researchers from the FDA and the NIH studied ginkgo’s effect on the combination of lopinavir/ritonavir (Kaletra, Aluvia for HIV/AIDS).
But only the midazolam interaction with ginkgo biloba appeared to be significant for patients. Continue reading Ginkgo biloba interacts with midazolam
 In this patient, it appears there was greater “blood thinning” effect when pomegranate was taken with warfarin (Coumadin), according to this report. Continue reading Does pomegranate interact with blood thinners?
From the St. Louis College of Pharmacy, in Missouri comes this report of an unusual case of verapamil (Calan SR) toxicity. Continue reading Interaction between grapefruit juice and verapamil
 Here’s a report from Spain of a patient who self-medicated with valerian (Valeriana officinalis L) and passionflower (Passiflora incarnata L) while taking lorazepam (Ativan, a benzodiazepine drug). Continue reading Report of a valerian-lorazepam drug interaction
Researchers from the Mayo Clinic in Rochester, Minnesota have reviewed the evidence and report that most interactions are confined to a relatively small number of drug classes and supplements. Continue reading Drug-supplement interactions in perspective
A reader who gets pain relief from this Chinese “herbal” product asks why it’s illegal in the US. Continue reading Tung Shueh Pills not legal in the US
An international group of researchers report on the ability of 3 herbal products commonly used in Cuba and Mexico to inhibit the action of the CYP450 system of drug metabolizing enzymes.
It’s relevant considering the millions of illegal aliens who have entered the US and bring their folk medicines with them. Continue reading Potential drug interactions with ethnic herbals
Dr. David Bailey from the University of Western Ontario in London, Canada reported the “grapefruit effect” more than 15 years ago — grapefruit juice increases levels of the high-blood-pressure drug felodipine (Plendil), causing potentially dangerous effects.
Now, during the National Meeting of the American Chemical Society, he reports more juice-drug interactions. Continue reading Take your medicine with water
Researchers from the University of Sydney in Australia have reviewed the evidence in children and adolescents.
The authors include data from adults, because if they limited the discussion to children and adolescents it would be a very short article.
That’s not a problem here. Continue reading CAM for psychiatric disorders in kids
In a pharmacy continuing education newsletter (InetCE 221-999-05-056-H01), Dr. Mary Chavez states, “St. John’s wort is the most studied herbal, and has the most evidence for significant interactions with medications.”
From her article, documented herbal-drug interactions based on reliable case reports, case series, or clinical investigations are presented below. I listed only generic drug names. A useful link to identify brand names from generic names is found here. Dr. Chavez includes more detailed information in the newsletter.
Ashwagandha (Withania somnifera; winter cherry) belongs to the pepper family. The root is used in Indian Ayurvedic medicine as an aphrodisiac, liver tonic, anti-inflammatory agent, and astringent.
People taking digoxin (Lanoxin) should be forewarned that tests to measure digoxin blood levels could be affected by the concurrent use of Ashwagandha, according to a study by researchers from the University of Texas, Houston. Continue reading Ashwagandha causes errors in measured digoxin blood levels
According to Dr. William McCloskey, the likelihood of drug:grapefruit juice interactions having a negative effect on a patient’s response to the drug has not been clearly established.
This might be due to the fact that many drugs affected by grapefruit juice have a wide therapeutic index. In other words, toxic blood levels are so much higher than the blood levels needed to achieve an effective treatment dose that any increase caused by grapefruit juice is not sufficient to reach toxicity.
That’s not to say there is no risk of a grapefruit juice:drug interaction.
Unfortunately, the source article has been deleted, but here’s the bottom line. If you take any of the drugs listed below and feel you must drink grapefruit juice, first discuss it with your doctor.
3/19/08 11:13 JR
This seems to be the first time the potential for these interactions has been studied.
Continue reading No interaction between goldenseal or kava kava and digoxin