Review: Prevalence of drug-herb and drug-supplement interactions in older adults

The title of this post should give it away (just saying).  However, I'm really glad I found this cause it was honestly the kind of paper I've been wanting to get my hands on for a very very very long time.  Reason why? It's has my philosophy wrapped into a paper: "how can we tell patients if their herbal use is bad for them if we don't have the reasoning why?"  Western medicine is so built upon prescription medication to solve problems, but that's not the mentality of most people.  With that being said, papers like these give an idea of possible mechanisms of herb-drug interactions and hopefully if patients are on these, then we know what to exactly tell them.

Highlights from the paper:

• cross-sectional study
• done in the UK
• published in British Journal of General Practice, October 2018
• Only 155 questionnaires were sent back (38.8% response rate)

Mentioned this database, Stockley's Herbal Medicine Interactions (Stockley's Herbal Medicines Interaction<-link is to the first edition of the book) and I'm planning to check that out later and see how extensive this is.

Herb-drug Interactions with Rationale

• Significant hazard,dosage adjustment or close monitoring is needed
• Bonecal-Levothyroxine: The efficacy of levothyroxine has been reduced by calcium carbonate. Calcium acetate and calcium citrate reduced levothyroxine absorption in pharmacokinetic studies
• Peppermint-Lansoprazole: Antacids may compromise the enteric coating of some commercially available peppermint oil capsules.  H2-receptor antagonists and proton pump inhibitors may interact similarly
• Doubt about outcome of current use
• Omega 3 fish oil-aspirin: The concurrent use of aspirin and fish oils caused at least additive effects on bleeding time in healthy subjects, but clinical studies in patients taking aspirin alone and with clopidogrel have found no evidence of an increase in incidence of bleeding episode
• Cod liver oil-Aspirin: The concurrent use of aspirin and fish oils caused at least additive effects on bleeding time in healthy subjects, but clinical studies in patients taking aspirin alone and with clopidogrel have found no evidence of an increase in incidence of bleeding episodes
• Cod liver oil-Bisoprolol/propanolol: the hypotensive effect of propanolol might be enhanced by fish oils
• Flaxseed-Rivaroxaban: Limited evidence suggests that flaxseed oil may have some antiplatelet effects, which could be additive with those of conventional antiplatelet drugs,and increase the risk of bleeding with anticoagulants
• Green tea-Lisinopril: both black and green tea might cause a modest increase in blood  pressure, which might detrimental to the treatment of hypertension.  Green tea reduced the effects of nadolol on blood pressure in healthy subjects.
• Senna pods-Indapamide: Theoretically, patients taking potassium-depleting diuretics could experience excessive potassium loss if they also regularly use, or abuse, anthraquinone-containing substances, such as senna
• Glucosamine-Co-codamol/Paracetamol: limited evidence suggests that glucosamine might reduce the efficacy of paracetamol (acetaminophen)
• Glucosamine-Furosemide/Bendroflumethiazide: limited evidence from a large open study suggests that unnamed diuretics might slightly reduce the efficacy of  glucosamine to some extent
• Echinacea-Midazolam: Echinacea does not appear to alter the AUC and clearance of oral midazolam, although the bioavailability may increased.  Clearance of intravenous midazolam may be modestly increased in patients taking Echinacea
• Hawthorn-Nifedipine: Limited evidence suggests that there may be additive blood pressure-lowering effects if hawthorn is taken with conventional antihypertensives, but the effects are small
• Visionace-Lansoprazole: The desired effect of beta carotene supplementation may be reduced in those taking proton pump inhibitors
• Evening primrose oil-Aspirin: evening primrose oil can inhibit platelet aggregation and increase bleeding time.  It has therefore been suggested that it may have additive effects with other antiplatelet drugs, but evidence of this is generally lacking.

I'll be highlighting this articles and others that show some herb-drug interactions.  Hopefully healthcare providers will incorporating more questions to ask patients about their herbal usage and see if there's serious interactions that need to be addressed.

Sources

original article