Administration of the increasingly popular dietary supplements containing quercetin may interfere with drug therapy. We intended to evaluate the online availability and quercetin content of the high‐dose mono‐component quercetin products and to review the potential use of quercetin products and their interactions with drugs. We monitored the online access to quercetin‐containing dietary supplements, collected the relevant information from the websites, procured selected products from the vendors, and subjected them to substance analysis. The quercetin content was quantified by an HPLC‐UV method. Twenty‐five websites offered mono‐component quercetin products, and nine products were procured. The quercetin content of eight products differed only ±10% from the nominal dose, whereas one product contained almost 30% more quercetin. Misleading indications such as antitumor and cardiovascular effects were often found on the sellers' websites. Quercetin‐containing dietary supplements are available online with misleading indications. The recommended daily doses are often high (occasionally over 1,000 mg), which may induce clinically relevant interactions with medications. Because high‐quercetin content of dietary supplements was confirmed, health care professionals should be aware of the unregulated internet market of dietary supplements and should consider the interactions of these substances with drugs.
In the present situation mapping these ambiguities and creating a standardized classification system would be advantageous.
Background Drug-drug interactions (DDIs) present a significant source of adverse drug reactions. Despite being one of the commonly cited risks to patient safety, prevention of DDIs still poses a challenge to healthcare systems. The prevalence of DDIs can be used as a quality indicator for the safety of prescribing. With the analysis of drug utilization databases, real-world data on critical DDIs can be obtained. The aim of this study was to establish a list of critical DDIs and estimate their prevalence in the Hungarian outpatient population. Methods Since there is no conclusive and generally accepted repository of high-risk DDIs, a systematic search of the literature for consensus-based lists was performed. Based on these results and their analysis with 5 interaction compendia, we propose a simple methodology to identify critical combinations. Present study focused on DDIs which are (1) of high clinical importance thus being most likely to cause significant harm if not detected, (2) well-supported by available evidence and (3) affect drugs which are routinely dispensed in the community pharmacy setting. A retrospective analysis of prescriptions filled between 2013 and 2016 was performed. The source of drug utilization data was the IQVIA’s national prescription fill database. The number of interacting drug pairs dispensed at the same time to the same patient was established. Results After excluding drugs with low dispensing rates, the analysis covered 39 DDIs. The distribution of risk categories of the analysed DDIs was inconsistent among different drug interaction compendia. The total number of prescriptions filled varied between 173924449 and 176368468 per year. The prevalence of the selected potential DDIs ranged from 0.00 to 355.89 per 100000 prescriptions per year. There was significant variation between how the number of cases had changed for each DDI throughout the study period, no general tendency could have been described. Conclusions There were 1.8 million cases of co-dispensing each year, where prescribers’ and community pharmacists’ role in recognizing and managing potentially serious interactions was or would have been critical. The method presented to identify high-risk DDIs can serve as a starting point for the much-needed improvement of routine interaction screening. Electronic supplementary material The online version of this article (10.1186/s40360-019-0311-0) contains supplementary material, which is available to authorized users.
BackgroundDue to the increasing number of supplementary products and patients taking supplements (dietary supplements, herb drugs, vitamins, etc) and OTC medications during their therapy, healthcare professionals have to take up the challenge of getting to know these products and identify any unwanted effects and drug–supplement interactions.PurposeIn association with the department of psychiatry and psychotherapy we purposed to identify patients’ motivation for supplement use, and evaluate and analyse potential interactions between drugs and supplement products in a patient group with unipolar major depression. We also aimed to estimate patient adherence to medical treatment.Material and methodsIn our study, we involved 54 inpatients and outpatients (men 16, women 38) in a point of care survey of 40–50 min. After voluntary interviews with a pharmacist, we checked the medical records of the patients. To identify interactions, we used four English language interaction checker databases (Micromedex Interaction Checker, Lexi-Interact, Medscape Interaction Checker and Drugs.com). Regarding the heterogenous nomenclature of the active ingredients of supplements and the fact that a few medicines were only available in our country and in central Europe, we had to standardise our screening methods. For pharmacokinetic and pharmacodynamic properties, and chemical structure of the drugs, we substituted these active ingredients with others presented in the databases above. To estimate adherence, we asked patients to complete the Morisky Medication Adherence Scale-4 survey.ResultsThe average number of products taken by patients were 8.7 prescribed medicines and 4.7 supplements. 90.8% of the patients took at least 1 supplement during 1 month prior to the survey. We identified in these 49 patients 68 supplement ingredients, 123 interactions and, in case of 5 patients (9.3%), we analysed potential severe interactions related to the use of supplements. By screening for adherence, we found a rate of 25.5% of non-adherent patients.ConclusionPharmacists should consider that a significant number of patients are taking supplements without any control of healthcare professionals, so they are exposed to the risk of severe interactions. We should aim to educate patients and improve interaction checker databases regarding supplement screening.References and/or acknowledgementsThis work was supported by the MGYT-KGYSZ.No conflict of interest
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