Prevalence of use and the risk of adverse effects associated with complementary and alternative medicine in a cohort of patients receiving warfarin

No improvement in disclosure of natural health product use to primary care medical doctors in the last 15 years: A survey of naturopathic patients

BACKGROUND

The use of natural health products (NHPs) is common in North America. In 2003, we found that 42% of NHP users had not disclosed this information to their primary care medical doctors (MDs). We repeated our survey in 2018/2019 to explore if the rate of NHP use disclosure had improved.

METHODS

From November 2018-February 2019, a 21-item survey about NHP use and disclosure was administered to adult patients who visited the Robert Schad Naturopathic Clinic in Toronto, Canada.

RESULTS

Almost all patients surveyed were using NHPs (99%), and 46% were using NHPs and prescription medication concurrently. Consistent with our 2003 findings, 42% of respondents who used NHPs did not disclose this information to their MD.

CONCLUSION

Disclosure of NHP use to MDs by naturopathic patients is limited and remained unchanged over the past 15 years. Future research should explore primary care MDs' hesitancy to inquire about patient NHP use.

Interaction between Traditional Chinese Medicine and Anticoagulant/Antiplatelet Drugs

Background:

Traditional Chinese medicine (TCM) has been used for medical purposes since the ancient time and has gradually gained recognition worldwide. Nowadays, patients with thrombus presiding to anticoagulant/ antiplatelet drugs prefer taking TCM. However, an increasing number of studies on herb–drug interactions have been shown. Nevertheless, findings are frequently conflicting and vague. In this review, we discuss the herb–drug interactions between TCM and anticoagulant/antiplatelet drugs to provide guidance on concomitant ingestion with anticoagulant/antiplatelet drugs.

Methods:

We undertook a structured search of medicine and drug databases for peer-reviewed literature using focused review questions.

Results:

Danshen, Ginkgo, Ginger, H. Perforatum, SMY and Puerarin injection had directional regulation effects on the efficacy of anticoagulant drugs by altering the CYPs, pharmacokinetic indexs and hemorheological parameters. H. Perforatum inhibited the efficacy of Clopidogrel by enhancing the CYP3A4 activity and Ginkgo increased the efficacy of Ticlopidine. Additionally, Renshen, the formulae except SMY and injections except Puerarin injection could increase or decrease the efficacy of anticoagulant/antiplatelet drugs via regulating the CYPs, platelet aggregation, hemorheological parameters and others.

Conclusion:

Some cases have reported that TCMs may increase the bleeding risk or has no effect on coagulation when anticoagulant/antiplatelet drugs are concurrently used. However, pharmacokinetic studies have presented either consistent or slightly varying results. So it is difficult to ascertain whether the concurrent use of TCM may increase or reduce the pharmacologic effects of anticoagulant/antiplatelet drugs with adverse reactions. Therefore, herb–drug interactions of TCM and anticoagulant/antiplatelet drugs should be further explored and defined.

The Effect of Ginger (Zingiber officinale) on Platelet Aggregation: A Systematic Literature Review

BACKGROUND

The potential effect of ginger on platelet aggregation is a widely-cited concern both within the published literature and to clinicians; however, there has been no systematic appraisal of the evidence to date.

METHODS

Using the PRISMA guidelines, we systematically reviewed the results of clinical and observational trials regarding the effect of ginger on platelet aggregation in adults compared to either placebo or baseline data. Studies included in this review stipulated the independent variable was a ginger preparation or isolated ginger compound, and used measures of platelet aggregation as the primary outcome.

RESULTS

Ten studies were included, comprising eight clinical trials and two observational studies. Of the eight clinical trials, four reported that ginger reduced platelet aggregation, while the remaining four reported no effect. The two observational studies also reported mixed findings.

DISCUSSION

Many of the studies appraised for this review had moderate risks of bias. Methodology varied considerably between studies, notably the timeframe studied, dose of ginger used, and the characteristics of subjects recruited (e.g. healthy vs. patients with chronic diseases).

CONCLUSION

The evidence that ginger affects platelet aggregation and coagulation is equivocal and further study is needed to definitively address this question.

Medical reconciliation of dietary supplements: don't ask, don't tell

OBJECTIVE

To explore inpatient reconciliation of dietary supplement (DS) use and determine characteristics associated with DS documentation.

METHODS

We analyzed DS use among 558 inpatients recruited from the Re-Engineered Discharge clinical trial to identify: (1) if patients self-reported DS and (2) if DS use was documented at admission. We examined socio-demographics for association with documentation using chi squares and t-tests. Logistic regression was performed to assess adjusted associations with DS documentation.

RESULTS

Sixty percent reported DS use (n=333). Among users, 36% had admission DS documentation, 20% were asked about use at admission, 18% reported disclosing use to a provider, and 48% reported they would continue to use DS. Overall, 6% of participants were asked, disclosed, and had documentation of DS. Logistic regression revealed increased age associated with lower odds of DS documentation. Identifying as Hispanic or African American reduces DS documentation odds compared to those identifying as white.

CONCLUSIONS

There is lack of consistent DS medical reconciliation in the inpatient setting. While more than half of patients used DS prior to hospitalization, most were not asked about use on admission.

PRACTICE IMPLICATIONS

This study adds to literature on medical reconciliation which requires that providers inquire and document patient DS use.

Exploring the decision to disclose the use of natural products among outpatients: a mixed-method study

Background

There is little understanding of the reasons for the limited communication between patients and conventional healthcare professionals regarding patients’ use of complementary and alternative medicine (CAM). The purpose of this study is to explore the predictors of outpatients’ decision to disclose their use of natural products to conventional healthcare professionals.

Methods

A mixed method design was used. Quantitative data were obtained through a survey and qualitative data were obtained from semi-structured interviews. A total of 257 outpatients who fulfilled the criteria of having used natural products prior to the interview were recruited for this study. Subsequently, 39 patients of those who completed the survey were further selected to take part in an in-depth qualitative interview.

Results

Predictors of the decision to disclose the use of natural products to conventional healthcare professionals included age, frequency of clinic visits, knowledge of the natural products and the attitude towards the benefits of CAM use. The themes that emerged from the qualitative data included safeness of the natural products, consulting alternative sources of information, apprehension regarding the development of negative relationships with healthcare professionals and reactions from the healthcare professionals.

Conclusions

Understanding the factors and reasons affecting patients’ decision as to whether to disclose their use of natural products provides an opportunity for conventional healthcare professionals to communicate better with patients. It is important to encourage patients to disclose their use of natural products in order to provide responsible health care as well as increasing patient safety regarding medication usage.

Study of natural health product adverse reactions (SONAR): active surveillance of adverse events following concurrent natural health product and prescription drug use in community pharmacies

BACKGROUND

Many consumers use natural health products (NHPs) concurrently with prescription medications. As NHP-related harms are under-reported through passive surveillance, the safety of concurrent NHP-drug use remains unknown. To conduct active surveillance in participating community pharmacies to identify adverse events related to concurrent NHP-prescription drug use.

METHODOLOGY/PRINCIPAL FINDINGS

Participating pharmacists asked individuals collecting prescription medications about (i) concurrent NHP/drug use in the previous three months and (ii) experiences of adverse events. If an adverse event was identified and if the patient provided written consent, a research pharmacist conducted a guided telephone interview to gather additional information after obtaining additional verbal consent and documenting so within the interview form. Over a total of 112 pharmacy weeks, 2615 patients were screened, of which 1037 (39.7%; 95% CI: 37.8% to 41.5%) reported concurrent NHP and prescription medication use. A total of 77 patients reported a possible AE (2.94%; 95% CI: 2.4% to 3.7%), which represents 7.4% of those using NHPs and prescription medications concurrently (95%CI: 6.0% to 9.2%). Of 15 patients available for an interview, 4 (26.7%: 95% CI: 4.3% to 49.0%) reported an AE that was determined to be "probably" due to NHP use.

CONCLUSIONS/SIGNIFICANCE

Active surveillance markedly improves identification and reporting of adverse events associated with concurrent NHP-drug use. Although not without challenges, active surveillance is feasible and can generate adverse event data of sufficient quality to allow for meaningful adjudication to assess potential harms.

Use of complementary and alternative medicine among USA adults with functional limitations: for treatment or general use?

OBJECTIVES

This study compared the use of complementary and alternative medicine (CAM) to treat health conditions with CAM use for general wellness or disease prevention among USA adults with and without functional limitations.

DESIGN

This was a cross-sectional survey.

METHODS

Data were obtained from the 2007 U.S. National Health Interview Survey (n=20,710).

RESULTS

Overall use of CAM treatment was higher among adults with functional limitations than among those without (61.4% versus 41.8%; p<0.001). Adults with functional limitations were more likely to use 3 of 4 CAM groupings: biologically based therapies (BBT) (47.9% versus 29.5%, p<0.001), manipulative and body-based therapies (73.7% versus 54.1%, p<0.001), and mind-body therapies (MBT) (39.3% versus 17.4%, p<0.001). Use of alternative medical systems for treatment was highly prevalent among adults (86.9% versus 80.0%, p=0.06), regardless of functional status. Adults with functional limitations were as likely to use CAM to treat the condition underlying their functioning difficulty (48.7%) as they were to treat other conditions (51.3%). Massage therapy was used most often to treat conditions that limited functional ability (53.4%). Older age was a predictor of the use of BBT for treatment, whereas younger age was a predictor of the use of MBT.

CONCLUSIONS

The prevalence of CAM use for treatment of conditions is high. Public health strategies are needed to promote disclosure of CAM use to health care providers, promote increased screening for CAM use by health care providers, and promote health care interactions that facilitate communication about CAM safety and efficacy.

Drug and dietary interactions of warfarin and novel oral anticoagulants: an update

Clinicians and patients around the world have been intrigued by the concept of developing an oral anticoagulant with a broad therapeutic window and few drug and dietary interactions that can be administered at fixed doses with no or minimal monitoring. The recently approved oral direct thrombin inhibitor dabigatran, along with the emerging oral anti-factor Xa inhibitors, rivaroxaban, apixaban, and edoxaban, have been developed to address many of the shortcomings of warfarin therapy. As warfarin is associated with extensive food and drug interactions, there is also a need to consider such interactions with the new oral anticoagulants. While to date few drug and dietary interactions have been reported with the new oral anticoagulants, it is still early in their development and clinical use cycle. Pharmacokinetic and pharmacodynamic profiles will have to be closely accounted for when determining the likelihood of a potential drug interaction prior to therapy initiation. As the list of drugs and supplements that interact with warfarin is continuously expanding, and the knowledge on drug interactions with the novel oral anticoagulants is still in its infancy, clinicians need to be vigilant when initiating any of these agents or when any changes in the patient's medication profile occur and perform a close screening for potential drug and dietary interactions. The objective of this paper is to give an update on drug and dietary interactions with warfarin and the novel oral anticoagulants, dabigatran, rivaroxaban, apixaban, and edoxaban.

Warfarin-associated bleeding events and concomitant use of potentially interacting medicines reported to the Norwegian spontaneous reporting system

AIMS

To study warfarin associated bleeding events reported to the Norwegian spontaneous reporting system and evaluate the differences in assessment of potentially interacting medicines between reporters and evaluators.

METHODS

Data on bleeding events on warfarin were retrieved from the Norwegian spontaneous reporting system database. Key measurements were time to bleeding, use of concomitant medications and the evaluation done by reporters.

RESULTS

In 289 case reports a total of 1261 medicines (median 4.0 per patient, range 1-17) was used. The evaluators (authors of this article) identified 546 medicines including warfarin (median 2.0 per patient, range 1-7) that could possibly cause bleeding alone or in combination. Reporters assessed 349 medicines (median 1.0 per patient, range 1-4) as suspect. Evaluators identified 156 pharmacokinetic and 101 pharmacodynamic interactions, compared with 19 pharmacokinetic and 56 pharmacodynamic interactions reported as suspected by the reporters. Time to bleeding was stated in 224 reports. Among the early bleeding events, the reports on warfarin without interacting medicines showed the highest INR (international normalized ratio). Heparin was used in 17/21 reported bleeding events during the first week on warfarin. Among the late bleeding events, reports with pharmacokinetic interacting medicines had the highest INR.

CONCLUSIONS

Concomitant use of potentially interacting medicines was involved in the majority of the warfarin-associated bleeding events reported to the Norwegian spontaneous reporting system. Reporters assessed mostly warfarin as the only contributor to bleeding. In particular, pharmacokinetically interacting medicines were not suspected as contributing to bleeding.

Warfarin and Supplement Interactions: Survey of Published Literature

Objective:

To review published literature related to potential interactions between warfarin and common dietary supplement products.

Data Sources:

Tertiary databases including Micromedex, LexiComp, and Natural Medicines Comprehensive Database were used to assess drug interactions with warfarin. Searches of literature from database inception through July 2010 were conducted in MEDLINE, International Pharmaceutical Abstracts, and Iowa Drug Information Service and were restricted to the English language. The following search terms were used: warfarin, ginkgo biloba, St. John's wort, garlic, coenzyme Q10, ginger, ginseng, red clover, fish oil, dong quai, cranberry, green tea, saw palmetto, bilberry, soy, chamomile, glucosamine, chondroitin, echinacea, interactions, anticoagulation/antiplatelet, bleeding, herbals, and pharmacokinetics/pharmacodynamics.

Study Selection and Data Extraction:

Thirty-two English language publications were identified and analyzed. Reference lists of each of the included articles were reviewed to obtain related articles for further analysis.

Data Synthesis:

Quality of existing data for interactions between warfarin and commonly available dietary supplements varies greatly. The majority of information available is derived from case reports, although for some products pharmacokinetic studies have been performed to assess the effect of supplement use in patients concurrently using warfarin. Some of the data that suggest interactions with warfarin were gleaned from case reports or from an understanding of supplement mechanisms of action that would indicate such an interaction. The strength of evidence for the majority of the herbal products studied seems to be lacking and therefore it is difficult to draw firm conclusions.

Conclusions:

Based on the narrow therapeutic window of warfarin therapy, practitioners should be encouraged to document any potential drug interaction. However, it seems inappropriate to suggest absolute avoidance of all dietary supplements in all patients using warfarin therapy. Instead, diligent monitoring and reporting should be implemented to detect such events.

Evaluation of the effect of lime fruit juice on the anticoagulant effect of warfarin

AIM

Citrus aurantifolia (Family Rutaceae) is commonly known as a familiar food and medicine, and s therapeutic effectiveness in a variety of diseases has been suggested in traditional medicine. Various complementary and alternative medicines (CAM) have been shown to interact with orthodox medicines. Hence, the aim of this study is to investigate such a phenomenon particularly the interaction of lime fruit juice with warfarin.

MATERIALS AND METHOD

Wistar strain albino rats of both sexes weighing between 190 and 230g were administered with oral doses of the respective drugs used depending on the groups of animals. Effects on the anticoagulant activity of warfarin were determined by standard laboratory methods.

RESULT

Lime fruit juice caused a reduction in the anticoagulant activity of warfarin.

CONCLUSION

This finding has shown that CAM can interact with orthodox medicines hence, warfarin prescribers need to be aware of the usage of CAM and monitor the international normalized ratio (INR) of their patients more frequently.

Patient Factors That Influence Warfarin Dose Response

Warfarin has long been the mainstay of oral anticoagulation therapy for the treatment and prevention of venous and arterial thrombosis. The narrow therapeutic index of warfarin, and the complex number of factors that influence international normalized ratio (INR) response, makes optimization of warfarin therapy challenging. Determination of the appropriate warfarin dose during initiation and maintenance therapy requires an understanding of patient factors that influence dose response: age, body weight, nutritional status, acute and chronic disease states, and changes in concomitant drug therapy and diet. This review will examine specific clinical factors that can affect the pharmacokinetics and pharmacodynamics of warfarin, as well as the role of pharmacogenetics in optimizing warfarin therapy.