Interactions between natural products and cancer treatments: underlying mechanisms and clinical importance

Natural products, also referred to as dietary supplements, complementary and alternative medicines, and health or food supplements are widely used by people living with cancer. These products are predominantly self-selected and taken concurrently with cancer treatments with the intention of improving quality of life, immune function and reducing cancer symptoms and treatment side effects. Concerns have been raised that concurrent use may lead to interactions resulting in adverse effects and unintended treatment outcomes. This review provides an overview of the mechanisms by which these interactions can occur and the current evidence about specific clinically important natural product-drug interactions. Clinical studies investigating pharmacokinetic interactions provide evidence that negative treatment outcomes may occur when Hypericum perforatum, Grapefruit, Schisandra sphenanthera, Curcuma longa or Hydrastis canadensis are taken concurrently with common cancer treatments. Conversely, pharmacodynamic interactions between Hangeshashinto (TJ-14) and some cancer treatments have been shown to reduce the side effects of diarrhoea and oral mucositis. In summary, research in this area is limited and requires further investigation.

Prevalence of drug-drug interactions in sarcoma patients: key role of the pharmacist integration for toxicity risk management

BACKGROUND

The risk of drug-drug interactions (DDI) has become a major issue in cancer patients. However, data in sarcoma patients are scarce. We aimed to evaluate the frequency and the factors associated with DDI with antitumor treatments, and to evaluate the impact of a pharmacist evaluation before anticancer treatment.

PATIENTS AND METHODS

We performed a retrospective review of consecutive sarcoma patients starting chemotherapy (CT) or Tyrosine kinase inhibitor (TKI). A pharmacist performed medication reconciliation and established an early toxicity risk assessment. Potential DDI with antitumor drugs were identified using Micromedex electronic software.

RESULTS

One hundred and twenty-two soft-tissue and 80 bone sarcoma patients (103 males, median age 50 years,) were included before CT (86%) or TKI (14%). The median number of medications was 3; 34 patients (22% of patients with medication reconciliation) reported complementary medicine use. 37 potential DDI classified as major, were identified (12% of the 243 pre-therapeutic assessments). In multivariate analysis, TKI (p < 0.0001), proton pump inhibitor (p = 0.026) and antidepressant (p < 0.001) were identified as risk factors of DDI (p < 0.02). Only marital status (p = 0.003) was associated with complementary medicine use. A pharmacist performed 157 medication reconciliations and made 71 interventions among 59 patients (37%). In multivariate analysis, factors associated with pharmacist intervention were: complementary medicines (p = 0.004), drugs number (p = 0.005) and treatment with TKI (p = 0.0002) CONCLUSIONS: Clinical interventions on DDI are more frequently required among sarcoma patients treated with TKI than CT. Multidisciplinary risk assessment including a medication reconciliation by a pharmacist could be crucial to prevent DDI with TKI.

Self-medication with herbal medicine and breast cancer survival: a prospective monocentric study

PURPOSE

The use of complementary and alternative medicine (CAM) is common among breast cancer patients, but less is known about whether CAM influences breast cancer survival. The primary aim of this study was to determine the impact of self-use of herbs on the overall survival.

METHODS

This was a prospective study including 110 patients with breast cancer. All patients were questioned about the concept of taking herbs. We analyzed the demographic data and the overall survival.

RESULTS

The average age was 51 years (30-80 years old). 37 had metastatic disease (33.6%). 48 patients had taken plants (43.6%). 19 patients consumed Graviola (39.6%) and 29 Alenda (60.4%). Overall survival at 3 years and at 5 years were, respectively, 96.2% and 82.4% in the absence of plant consumption versus 78.5% and 78.5% in case of plant consumption (p = 0.015).

CONCLUSION

This study concluded that self-medication with Graviola or Alenda may be associated with an increase of death risk in patients with breast cancer. Further studies are needed to confirm these results.

Improving pharmacy practice in relation to complementary medicines: a qualitative study evaluating the acceptability and feasibility of a new ethical framework in Australia

BACKGROUND

There is a need for clearer guidance for pharmacists regarding their responsibilities when selling complementary medicines. A recently published ethical framework provides guidance regarding the specific responsibilities that pharmacists need to meet in order to fulfil their professional obligations and make a positive contribution to health outcomes when selling complementary medicines.

OBJECTIVE

Evaluate the acceptability and feasibility of a new ethical framework for the sale of complementary medicines in community pharmacy.

METHODS

Australian community pharmacists were invited to participate in online focus groups and interviews. Participants were recruited via multiple methods, including social media and the professional networks of pharmacy groups. Participants were provided the ethical framework prior to the discussion. Discussions were transcribed verbatim and analysed using thematic analysis.

RESULTS

Seventeen community pharmacists participated in the study (11 in 4 focus groups and 6 in individual interviews). There was good representation among participants in terms of gender, years of practice, pharmacy location and script volume. Participants differed in how proactive they were in relation to selling and providing advice on complementary medicines, how they interpreted evidence in relation to complementary medicines, and how they navigated their practice within the retail environment of community pharmacy. The majority of participants found the framework was acceptable for practice and was feasible for implementation with targeted support. Participants identified two important areas for targeted support in implementing the framework: improved access to evidence-based information resources on complementary medicines and independent evidence-based education and training on complementary medicine for pharmacists and pharmacy support staff.

CONCLUSION

The ethical framework addresses an important gap in providing specific professional guidance to pharmacists when selling complementary medicines. The results of the study suggest that the framework may be acceptable to community pharmacists and be feasible to implement with targeted support.

The provision of care provided by the pharmacy workforce in relation to complementary medicines in Australia

BACKGROUND

The use of complementary medicines (CMs) is prevalent across the world. Some CMs, such as St John's Wort, when taken with specific pharmaceutical medicines, may cause drug-herb interactions. In this context, pharmacists have the opportunity to play an important role in preventing harm to patients.

OBJECTIVE

The aim of this study was to explore real-life pharmacy practice in relation to CMs in New South Wales, Australia.

METHODS

The study design involved 'pseudo-patient' pharmacy visits while posing as a patient's relative requesting St John's Wort and using a standardized set of questions to document details of the interaction with a range of pharmacy staff.

RESULTS

Of the 110 metropolitan pharmacy visits made, the pharmacy workforce who were involved in assisting the pseudo-patient's request included 51 pharmacists (46.4%), 57 pharmacy assistants (51.8%) and 1 naturopath (0.9%). Advice that may have resulted in harm to the patient, was offered by pharmacists in 11.8% (n = 13) of the encounters, and 20.9% (n = 23) by pharmacy assistants. Conversely, advice that prevented harm was provided by only 17.3% (n = 19) pharmacists and 10.9% (n = 12) pharmacy assistants. History-taking was not attempted by 84 pharmacy staff.

CONCLUSION

The majority of pharmacy staff involved in this study did not manage a request for a CM with known drug-herb interactions in a way that would prevent harm. These findings highlight the need for the pharmacy workforce to engage in education and training in CMs, with a focus on how to consult evidence-based resources regarding interactions in the interest of patient safety.

Involving systems thinking and implementation science in pharmacists' emerging role to facilitate the safe and appropriate use of traditional and complementary medicines

The use of traditional and complementary medicines (TM/CMs) has become an increasingly popular part of healthcare and self-care practices across the world. While the benefits and risks of many TM/CMs are yet to be fully evaluated, their prevalent use without consistent oversight has not been fully addressed by the public health sector. Pharmacists play an integral role in contributing to public health. Discussion about integrating TM/CMs into the professional practice of the pharmacist began over two decades ago. Nevertheless, TM/CMs are predominantly managed as "retail products" and are not integrated into pharmaceutical care and practice. While some isolated measures towards integration have been proposed, there remains no consensus on how to deliver pharmaceutical care in a coordinated, systematic manner. Systems thinking approaches are needed to formulate and implement strategies that change pharmacists' practice related to TM/CMs. Such approaches will ultimately reduce risk, optimize patient care, and result in better health outcomes.

Complementary and alternative medicine beliefs in type 2 diabetes: The Fremantle Diabetes Study Phase II

Complementary medicine (CM) treatment beliefs of people with type 2 diabetes were assessed using a validated three-domain questionnaire. Belief in holistic health, but not natural treatments or participation in treatment, was independently associated with CM use (P = 0.003). Strong holistic health beliefs could identify present/future CM use, with potential management implications.

An ethical framework for the responsibilities of pharmacists when selling complementary medicines

BACKGROUND

Whether pharmacists should sell complementary medicines that lack evidence of effectiveness is an important ethical question which is not explicitly addressed in the existing literature or professional guidelines. The question arises because many complementary medicines lack rigorous evidence that they are effective. There is a need for specific practical guidance for pharmacists regarding their responsibilities when selling complementary medicines.

OBJECTIVE

Outline and defend an ethical framework for the responsibilities of pharmacists when selling complementary medicines.

METHOD

Principle-based ethics consists in the application of the four bioethical principles to make decisions in healthcare. A public health argument is provided that supports the sale of complementary medicines in pharmacy providing pharmacists meet a number of specific professional responsibilities. The theoretical resources provided by principle-based ethics are used to develop and defend a framework for the responsibilities of pharmacists when selling complementary medicines. The proposed framework is defended against counter-arguments that propose a stricter or more lenient approach.

RESULTS

The framework identifies the following responsibilities of pharmacists selling complementary medicines: (1) pharmacists should provide evidence-based recommendations to consumers regarding complementary medicines, (2) pharmacists should train all staff in a pharmacy to ensure that they provide evidence-based recommendations regarding complementary medicines and refer to a pharmacist when required, (3) when providing advice, pharmacists should provide sufficient information for consumers to make informed decisions, (4) pharmacists should setup the pharmacy so that consumers are offered advice from a pharmacist when purchasing complementary medicines; pharmacists need to be available to provide that advice, and (5) pharmacists must be vigilant for complementary medicine harm and intervene if risk of harm is significant.

CONCLUSION

The framework provides practical guidance for pharmacists regarding their responsibilities when selling complementary medicines.

Yes to Recreational Drugs and Complementary Medicines But No to Life-Saving Medications: Beliefs Underpinning Treatment Decisions Among PLHIV

Despite the life-preserving benefits of antiretroviral therapy (ART), some people living with HIV (PLHIV) delay, decline or diverge from recommended treatment while paradoxically being willing to use potentially dangerous substances, such as recreational drugs (RD) and complementary medicines (CM). During 2016 and 2017, interviews were conducted with 40 PLHIV, in Australia to understand drivers underpinning treatment decisions. While many believed ART to be effective, they expressed concerns about long-term effects, frustration over perceived lack of autonomy in treatment decisions and financial, emotional and physical burdens of HIV care. In contrast, they ascribed a sense of self-control over the use of RD and CM, along with multiple professed benefits. The perceived burden of ART emerged as a motivator for deviating from recommended treatment, while positive views towards RD and CM appear to justify use. This study may serve as guidance for the development of future strategies to address barriers to treatment uptake and adherence and subsequently health outcomes for PLHIV in Australia and elsewhere.

Complementary medicines use amongst elective surgery patients at a public tertiary hospital: A prospective observational cohort study in Australia

BACKGROUND

and purpose. Complementary medicines (CM) use may result in untoward effects perioperatively. The study purpose is to identify CM pattern of use amongst elective surgery patients, and improve effectiveness of information collection relating to CM use.

MATERIALS AND METHODS

This is a prospective observational cohort study. CM questionnaire was administered alongside standard hospital forms at pre-admission clinic over eight weeks.

RESULTS

992 patients attended pre-admission clinic; 317 patients were included in analysis. Introduction of CM questionnaire increased disclosure rate by 11.7% giving a total prevalence of 44.2%. CM use was significantly higher in females and in older patients. Top CM reported were vitamin D (12%) and omega-3 (12%). Majority of patients did not plan to withhold CM before surgery, and were not concerned about perioperative risks.

CONCLUSION

Pre-admission clinics need to encourage CM disclosure. Patient education of potential risks and greater engagement of clinicians in patient assessment is required.

Sources, distribution, bioavailability, toxicity, and risk assessment of heavy metal(loid)s in complementary medicines

The last few decades have seen the rise of alternative medical approaches including the use of herbal supplements, natural products, and traditional medicines, which are collectively known as 'Complementary medicines'. However, there are increasing concerns on the safety and health benefits of these medicines. One of the main hazards with the use of complementary medicines is the presence of heavy metal(loid)s such as arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg). This review deals with the characteristics of complementary medicines in terms of heavy metal(loid)s sources, distribution, bioavailability, toxicity, and human risk assessment. The heavy metal(loid)s in these medicines are derived from uptake by medicinal plants, cross-contamination during processing, and therapeutic input of metal(loid)s. This paper discusses the distribution of heavy metal(loid)s in these medicines, in terms of their nature, concentration, and speciation. The importance of determining bioavailability towards human health risk assessment was emphasized by the need to estimate daily intake of heavy metal(loid)s in complementary medicines. The review ends with selected case studies of heavy metal(loid) toxicity from complementary medicines with specific reference to As, Cd, Pb, and Hg. The future research opportunities mentioned in the conclusion of review will help researchers to explore new avenues, methodologies, and approaches to the issue of heavy metal(loid)s in complementary medicines, thereby generating new regulations and proposing fresh approach towards safe use of these medicines.

Comparative analysis of speciation and bioaccessibility of arsenic in rice grains and complementary medicines

In many countries, rice grains and complementary medicines are important sources of arsenic (As) consumption. The objective of this study was to compare the speciation and bioaccessibility of As in selected rice grains and complementary medicines. A number of rice grain samples, and a range of herbal and ayurvedic medicines were analyzed for total As, speciation of As using sequential fractionation and extended x-ray absorption fine structure (EXAFS) techniques, and bioaccessibility of As using an in vitro extraction test. The daily intake of As through the uptake of these As sources was compared with the safety guidelines for As. The results demonstrated higher levels of As in ayurvedic medicines compared to herbal medicines and rice grains. The sequential fractionation showed the dominance of organic-bound As species in rice grains and herbal medicines, however, inorganic-bound As species dominated the ayurvedic medicines. This implies that As is derived from plant uptake in herbal medicines and rice grains, and from inorganic mineral input in ayurvedic medicines. Arsenic bioaccessibility was higher in ayurvedic than herbal medicines and rice grains, suggesting that inorganic As added as a mineral therapeutic input is more bioaccessible than organic As species derived from plant uptake. This study also showed a positive relationship between soluble As fractions and bioaccessibility indicating that solubility is an important factor controlling bioaccessibility. The daily intake values for As as estimated by total As content are likely to exceed the safe threshold level in rice grains that are enriched with As.

Key stakeholder perspectives on the barriers and solutions to pharmacy practice towards complementary medicines: an Australian experience

BACKGROUND

Although pharmacists are entrusted to play a role in ensuring the safe and appropriate use of all medicines, in general, the inclusion of complementary medicines (CMs) into their professional practice has not been observed. The purpose of this study was to explore the perceptions and opinions of pharmacists and 8 key stakeholder leaders regarding the barriers that hinder pharmacists from providing care related to the use of CMs by patients/consumers and to identify solutions that would support pharmacists' in extending their role in this area.

METHODS

Semi-structured key informant interviews were conducted with 2 practicing pharmacists, 1 pharmacy owner, 1 key representative of a pharmacist professional organization, 1 key representative of a consumer advocacy group, 1 key representative of a medical professional organization, 1 key representative from a complementary medicine practitioner professional organization, 1 leader within a pharmacy school, 2 senior staff from a regulatory authority, and 1 key representative of the complementary medicine industry in Australia.

RESULTS

A total of 9 barriers were identified in this study. Barriers including a lack of CMs knowledge, doubts about the evidence-base, a lack of research skills and access to reliable and reputable information dominated the discussions. A total of 7 solutions were proposed. Of those, the integration of CMs curricula into under-graduate and professional pharmacy education, and defining a clearer role for pharmacists' standard of practice were considered the most important. Apposing opinions about the role of naturopaths in pharmacies were identified..

CONCLUSION

It is anticipated that pharmacists will be required to formalise a role in ensuring the safe and appropriate use of complementary medicines to fulfil their professional and ethical responsibilities. However, pharmacists in general are not ready to take up this extended role. Individual key stakeholder groups have considered the existing barriers and have proposed solutions that are isolated measures. To facilitate further developments related to CMs and the professional practice of pharmacy, collaborative efforts between key stakeholders are needed to strategically plan and execute an extended role in a unified manner.

An assessment of the impact of herb-drug combinations used by cancer patients

BACKGROUND

Herb/Dietary Supplements (HDS) are the most popular Complementary and Alternative Medicine (CAM) modality used by cancer patients and the only type which involves the ingestion of substances which may interfere with the efficacy and safety of conventional medicines. This study aimed to assess the level of use of HDS in cancer patients undergoing treatment in the UK, and their perceptions of their effects, using 127 case histories of patients who were taking HDS. Previous studies have evaluated the risks of interactions between HDS and conventional drugs on the basis on numbers of patient using HDSs, so our study aimed to further this exploration by examining the actual drug combinations taken by individual patients and their potential safety.

METHOD

Three hundred seventy-five cancer patients attending oncology departments and centres of palliative care at the Oxford University Hospitals Trust (OUH), Duchess of Kent House, Sobell House, and Nettlebed Hospice participated in a self-administered questionnaire survey about their HDS use with their prescribed medicines. The classification system of Stockley's Herbal Medicine's Interactions was adopted to assess the potential risk of herb-drug interactions for these patients.

RESULTS

127/375 (34 %; 95 % CI 29, 39) consumed HDS, amounting to 101 different products. Most combinations were assessed as 'no interaction', 22 combinations were categorised as 'doubt about outcomes of use', 6 combinations as 'Potentially hazardous outcome', one combination as an interaction with 'Significant hazard', and one combination as an interaction of "Life-threatening outcome". Most patients did not report any adverse events.

CONCLUSION

Most of the patients sampled were not exposed to any significant risk of harm from interactions with conventional medicines, but it is not possible as yet to conclude that risks in general are over-estimated. The incidence of HDS use was also less than anticipated, and significantly less than reported in other areas, illustrating the problems when extrapolating results from one region (the UK), in one setting (NHS oncology) in where patterns of supplement use may be very different to those elsewhere.

Speciation and bioavailability of lead in complementary medicines

Complementary medicines have associated risks which include toxic heavy metal(loid) and pesticide contamination. The objective of this study was to examine the speciation and bioavailability of lead (Pb) in selected complementary medicines. Six herbal and six ayurvedic medicines were analysed for: (i) total heavy metal(loid) contents including arsenic (As), cadmium (Cd), Pb and mercury (Hg); (ii) speciation of Pb using sequential fractionation and extended x-ray absorption fine structure (EXAFS) techniques; and (iii) bioavailability of Pb using a physiologically-based in vitro extraction test (PBET). The daily intake of Pb through the uptake of these medicines was compared with the safety guidelines for Pb. The results indicated that generally ayurvedic medicines contained higher levels of heavy metal(loid)s than herbal medicines with the amount of Pb much higher than the other metal(loid)s. Sequential fractionation indicated that while organic-bound Pb species dominated the herbal medicines, inorganic-bound Pb species dominated the ayurvedic medicines. EXAFS data indicated the presence of various Pb species in ayurvedic medicines. This implies that Pb is derived from plant uptake and inorganic mineral input in herbal and ayurvedic medicines, respectively. Bioavailability of Pb was higher in ayurvedic than herbal medicines, indicating that Pb added as a mineral therapeutic input is more bioavailable than that derived from plant uptake. There was a positive relationship between soluble Pb fraction and bioavailability indicating that solubility is an important factor controlling bioavailability. The daily intake values for Pb as estimated by total and bioavailable metal(loid) contents are likely to exceed the safe threshold level in certain ayurvedic medicines. This research demonstrated that Pb toxicity is likely to result from the regular intake of these medicines which requires further investigation.