Herbal and dietary supplement--drug interactions in patients with chronic illnesses.
Dr. Oesterheld’s Comment: This article reviews an important drug interaction area. I generally agree with the descriptions of drug interactions with St Johns wort and other herbals with chronically used medications. However, there is a tendency to jump to class conclusions. For example, because there is an interaction with amitriptyline and St John's wort, it is suggested that all tricyclics are likely to be so affected. Since there are difference in the metabolic pathways of individual TCAs, St John’s wort may not equally inhibit all P450 cytochrome pathways and thus, it may not affect ALL TCAs. In addition drug interactions with echinacea are described as unlikely when the literature suggests that they may indeed exist. Otherwise, this review stands.Abstract:Am Fam Physician. 2008 Jan 1;77(1):73-8.Links
Herbal and dietary supplement–drug interactions in patients with chronic illnesses.
Gardiner P, Phillips R, Shaughnessy AF.
Herbs, vitamins, and other dietary supplements may augment or antagonize the actions of prescription and nonprescription drugs. St. John’s wort is the supplement that has the most documented interactions with drugs. As with many drug-drug interactions, the information for many dietary supplements is deficient and sometimes supported only by case reports. Deleterious effects are most pronounced with anticoagulants, cardiovascular medications, oral hypoglycemics, and antiretrovirals. Case reports have shown a reduction in International Normalized Ratio in patients taking St. John’s wort and warfarin. Other studies have shown reduced levels of verapamil, statins, digoxin, and antiretrovirals in patients taking St. John’s wort. Physicians should routinely ask patients about their use of dietary supplements when starting or stopping a prescription drug, or if unexpected reactions occur. PMID: 18236826