Dietary supplement use among anticoagulation clinic patients

The Clinical Significance of Drug-Food Interactions of Direct Oral Anticoagulants

Cardiovascular diseases are the most common cause of death in the world. For almost 60 years, vitamin K antagonists (VKAs) were the mainstay of anticoagulation therapy, but in recent years direct oral anticoagulants (DOACs) have become the anticoagulant treatment of choice. DOACs were initially considered drugs with no significant food interactions; however, clinical observations from daily practice have proved otherwise as interactions with food ingredients have been reported. Food, dietary supplements or herbs may contain substances that, when administered concomitantly with DOACs, can potentially affect the plasma concentration of the drugs. The aim of this paper was to evaluate the clinical significance of drug-food interactions of DOACs, such as dabigatran, rivaroxaban, apixaban, edoxaban and betrixaban. Patients treated with anticoagulants should avoid products containing St. John's wort and take special care with other food ingredients. As the interest in dietary supplements is on the rise, healthcare providers can contribute to the development of well-designed clinical trials on interactions between DOACs and food, and distribute sufficient knowledge about the proper use of these supplements among patients.

Prevalence and Knowledge of Potential Interactions Between Over-the-Counter Products and Apixaban

BACKGROUND

Direct-acting oral anticoagulants (DOACs), such as apixaban, are the most commonly prescribed anticoagulants, with advantages in that they do not require routine monitoring. However, less frequent contact with healthcare professionals may contribute to poor patient knowledge about potential interactions between over-the-counter (OTC) products and DOACs.

OBJECTIVE

Determine the prevalence of use of OTC products (OTC medications and dietary supplements) with potentially serious apixaban interactions and assess patient knowledge of potential interactions.

DESIGN

Cross-sectional survey.

SETTING

Academic-affiliated outpatient medical practices in northern and southern California.

PARTICIPANTS

A total of 791 English- or Spanish-speaking patients prescribed apixaban.

MEASUREMENTS

Use and knowledge of OTC medications and dietary supplements with potentially serious apixaban interactions.

RESULTS

Almost all respondents (n = 771; 97.5%) reported OTC product use. Of respondents, 33% (n = 266) took at least one OTC product with potentially serious apixaban interactions daily/most days and 53 (6.7%) took multiple products (mean = 2.6 [SD = 2.6]). Aspirin was taken daily by 116 (14.7%; of which 75 [64.7%] also consumed other potentially interacting OTC products), and some days/as needed by an additional 82 (10.4%). Ibuprofen and naproxen were taken daily/most days by 14 (1.8%) and occasionally by 225 (28.5%). Dietary supplements with potentially serious interactions were taken daily/most days by 160 (20.2%). Approximately 66% of respondents were either uncertain or incorrect about the potential for increased bleeding from combining nonsteroidal anti-inflammatory drugs and apixaban. Less knowledge about OTC products with potentially serious interactions was associated with greater OTC product use (odds ratio = 0.54; 95% confidence interval = 0.35-0.85).

CONCLUSION

Significant numbers of patients take OTC products (particularly dietary supplements) with potentially serious interactions with the DOAC apixaban and appear to lack knowledge about potentially harmful interactions. Interventions are needed to educate patients and healthcare providers about potential dangers of taking interacting OTC products in combination with apixaban, and data are needed on outcomes associated with concomitant apixaban-OTC product use. J Am Geriatr Soc 68:155-162, 2019.

How do pharmacists use and recommend vitamins, minerals, herbals and other dietary supplements?

Background

Use of complementary and alternative medicine (CAM), including vitamins, minerals, herbals, and other dietary supplements, is widespread in the United States (ranging from 24% in Hispanics to 50% in American Indians). Pharmacists are an accessible source for healthcare information, but little is known about their use of CAM products and to whom they would recommend these products.

Methods

A cross-sectional survey was sent via email to pharmacists licensed in one state in the United States in 2015. The survey included items about their use of 10 vitamins and minerals, and 21 herbal or other dietary supplements, as well as reasons for use, conditions used to treat, if they would recommend the product to patients, family, or friends, their perception of CAM safety and effectiveness, and four demographic questions. Descriptive statistics were used to summarize the data, and a chi-square test was used to determine differences between pharmacists’ use of vitamins/minerals and herbals/other dietary supplements. The a priori alpha level was 0.05.

Results

A total of 639 pharmacists completed the survey. Female pharmacists used vitamins/minerals (p = 0.031) and herbals/others (p = 0.039) more than male pharmacists. Older pharmacists used herbals/others more than younger pharmacists (p < 0.001). Fifty-nine percent thought the dietary supplements in the survey were safe while 32% reported they were effective. Seventy-eight percent of respondents reported use of any vitamin or mineral product versus 42% who reported use of any herbal or other dietary supplement. Commonly used products included: multivitamins (91%), vitamin C (71%), fish oil (65%), probiotics (53%), and fiber (53%). The most commonly reported reason for use was general health and wellness (17–90%). Pharmacists most commonly recommend fiber/psyllium (94%) and calcium (90%) to patients, family, and friends.

Conclusions

Pharmacists in this survey selectively used vitamins, minerals, herbals and other dietary supplements, and recommended some of the more commonly used products to patients, family and friends. This is valuable information given that pharmacists are frontline healthcare professionals who may be asked to provide advice about these products.

Electronic supplementary material

The online version of this article (10.1186/s12906-019-2637-y) contains supplementary material, which is available to authorized users.

Oral anticoagulant therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

The objective of this article is to summarize the published literature concerning the pharmacokinetics and pharmacodynamics of oral anticoagulant drugs that are currently available for clinical use and other aspects related to their management.

METHODS

We carried out a standard review of published articles focusing on the laboratory and clinical characteristics of the vitamin K antagonists; the direct thrombin inhibitor, dabigatran etexilate; and the direct factor Xa inhibitor, rivaroxaban

RESULTS

The antithrombotic effect of each oral anticoagulant drug, the interactions, and the monitoring of anticoagulation intensity are described in detail and discussed without providing specific recommendations. Moreover, we describe and discuss the clinical applications and optimal dosages of oral anticoagulant therapies, practical issues related to their initiation and monitoring, adverse events such as bleeding and other potential side effects, and available strategies for reversal.

CONCLUSIONS

There is a large amount of evidence on laboratory and clinical characteristics of vitamin K antagonists. A growing body of evidence is becoming available on the first new oral anticoagulant drugs available for clinical use, dabigatran and rivaroxaban.

Challenges of Older Patients’ Knowledge About Warfarin Therapy

Objective: To review the challenges of warfarin education for older patients (aged 65 years or older) in terms of knowledge, access to warfarin education, and education resources. Methods: A quasi-systematic review of the literature was performed via electronic database searches (eg, Medline, Embase, Cumulative Index to Nursing and Allied Health Literature, International Pharmaceutical Abstracts, Meditext, and Google Scholar) from 1990 to May 2011. Results: The 62 articles reviewed found that improved patient knowledge results in better anticoagulation control. The review also found that between 50% and 80% of older patients have inadequate knowledge about the basic aspects of warfarin therapy (eg, action, benefits and risks, interactions with other drugs or foods, international normalized ratio management). Demographic factors, such as advancing age, lower family income, and limited health literacy, were found to inversely affect patients’ warfarin knowledge, and access to warfarin education and information resources were often suboptimal in different practice settings. Finally, a number of educational strategies and resources that could be readily incorporated to improve the effectiveness of current warfarin education programs were extracted from the review. Conclusion: This comprehensive review highlights that education about warfarin in older patients is currently suboptimal and may in part contribute to poor therapeutic outcomes. This review article also acknowledges the need to identify, target, and develop educational strategies and resources to further improve older patients’ knowledge about their warfarin therapy.

Pharmacology and management of the vitamin K antagonists: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This article concerning the pharmacokinetics and pharmacodynamics of vitamin K antagonists (VKAs) is part of the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). It describes the antithrombotic effect of the VKAs, the monitoring of anticoagulation intensity, and the clinical applications of VKA therapy and provides specific management recommendations. Grade 1 recommendations are strong and indicate that the benefits do or do not outweigh the risks, burdens, and costs. Grade 2 recommendations suggest that the individual patient's values may lead to different choices. (For a full understanding of the grading, see the "Grades of Recommendation" chapter by Guyatt et al, CHEST 2008; 133:123S-131S.) Among the key recommendations in this article are the following: for dosing of VKAs, we recommend the initiation of oral anticoagulation therapy, with doses between 5 mg and 10 mg for the first 1 or 2 days for most individuals, with subsequent dosing based on the international normalized ratio (INR) response (Grade 1B); we suggest against pharmacogenetic-based dosing until randomized data indicate that it is beneficial (Grade 2C); and in elderly and other patient subgroups who are debilitated or malnourished, we recommend a starting dose of < or = 5 mg (Grade 1C). The article also includes several specific recommendations for the management of patients with nontherapeutic INRs, with INRs above the therapeutic range, and with bleeding whether the INR is therapeutic or elevated. For the use of vitamin K to reverse a mildly elevated INR, we recommend oral rather than subcutaneous administration (Grade 1A). For patients with life-threatening bleeding or intracranial hemorrhage, we recommend the use of prothrombin complex concentrates or recombinant factor VIIa to immediately reverse the INR (Grade 1C). For most patients who have a lupus inhibitor, we recommend a therapeutic target INR of 2.5 (range, 2.0 to 3.0) [Grade 1A]. We recommend that physicians who manage oral anticoagulation therapy do so in a systematic and coordinated fashion, incorporating patient education, systematic INR testing, tracking, follow-up, and good patient communication of results and dose adjustments [Grade 1B]. In patients who are suitably selected and trained, patient self-testing or patient self-management of dosing are effective alternative treatment models that result in improved quality of anticoagulation management, with greater time in the therapeutic range and fewer adverse events. Patient self-monitoring or self-management, however, is a choice made by patients and physicians that depends on many factors. We suggest that such therapeutic management be implemented where suitable (Grade 2B).

Dietary supplements, herbs and oral anticoagulants: the nature of the evidence

In the US, the use of dietary supplements, including vitamins, minerals, amino acids, and herbal products, is extensive. Nonetheless, the majority of patients report that they have little information about the risks, benefits, and adverse effects of medicines, or about their potential interactions with prescription drugs. Patients taking warfarin are at particular risk of interactions with dietary supplements, yet approximately 30% use herbal or natural product supplements on a regular basis. No current governmental regulations or voluntary programs address dietary supplement interactions with prescription drugs. Case reports represent the majority of the evidence surrounding drug interactions between warfarin and dietary supplements. Those of the highest quality include, as an assessment of causality, a modification of the recently published Drug Interaction Probability Scale. Despite positive case reports, formal drug interaction studies are often negative, suggesting that numerous patient-specific influences other than the suspected interaction alone may be responsible for a particular observation. The cranberry-juice/warfarin interaction is a recent example of such a discrepancy. Healthcare providers can play an active role in improving quantity and the quality of case reports of interactions involving warfarin and dietary supplements. A registry of anticoagulant interactions with dietary supplements has been proposed, and is currently being developed through Clotcare Online Resource (http://www.clotcare.com). The goal of this registry is to obtain high quality case-based evidence of drug interactions between anticoagulants and dietary supplements, to define these interactions based on clinical and monitoring outcomes, and to analyze likelihood of causation using a modification of the Drug Interaction Probability Scale.