Pharmacy study of natural health product adverse reactions (SONAR): a cross-sectional study using active surveillance in community pharmacies to detect adverse events associated with natural health products and assess causality

Abstract

ObjectivesTo investigate the rates and causality of adverse event(s) (AE) associated with natural health product (NHP) use, prescription drug use and concurrent NHP-drug use through active surveillance in community pharmacies.DesignCross-sectional study of screened patients.Setting10 community pharmacies across Alberta and British Columbia, Canada from 14 January to 30 July 2011.ParticipantsThe participating pharmacy staff screened consecutive patients, or agents of patients, who were dropping or picking up prescription medications.Primary outcome measuresPatients were screened to determine the proportions of them using prescription drugs and/or NHPs, as well as their respective AE rates. All AEs reported by the screened patients who took a NHP, consented to, and were available for, a detailed telephone interview (14%) were adjudicated fully to assess for causality.ResultsOver a total of 105 pharmacy weeks and 1118 patients screened, 410 patients reported taking prescription drugs only (36.7%; 95% CI 33.9% to 39.5%), 37 reported taking NHPs only (3.3%; 95% CI 2.4% to 4.5%) and 657 reported taking prescription drugs and NHPs concurrently (58.8%; 95% CI 55.9% to 61.6%). In total, 54 patients reported an AE, representing 1.2% (95% CI 0.51% to 2.9%), 2.7% (95% CI 0.4% to 16.9%) and 7.3% (95% CI 5.6% to 9.6%) of each population, respectively. Compared with patients who reported using prescription drugs, the patients who reported using prescription drugs and NHPs concurrently were 6.4 times more likely to experience an AE (OR; 95% CI 2.52 to 16.17; p<0.001). Combined with data from Ontario, Canada, a national proportion was calculated, which found that 45.4% (95% CI 43.8% to 47.0%) of Canadians who visit community pharmacies take NHPs and prescription drugs concurrently, and of those, 7.4% (95% CI 6.3% to 8.8%) report an AE.ConclusionsA substantial proportion of community pharmacy patients use prescription drugs and NHPs concurrently; these patients are at a greater risk of experiencing an AE. Active surveillance provides a means of detecting such AEs and collecting high-quality data on which causality assessment can be based.

Pediatric Integrative Medicine

“…6 Despite the fact that natural health products may be perceived as safe because of their natural origins, researchers have demonstrated the potential for serious toxicity and possible adverse reactions or events, especially in patients taking prescription medications concurrently. 85 Compounding this risk is the fact that safety standards that specifically address the pediatric population are lacking, 86 and parents may be reluctant to disclose the use of natural products for fear of censure or ridicule. 6 Failure of pharmacists and physicians to routinely inquire about natural health product use is another significant compounder.…”

Concurrent use of herbal supplements and prescription drugs in northeastern Puerto Rico

“…At the same time, it is clear that some herbal supplements could put patients at risk for harm when those patients use these kinds of supplements concomitantly with prescription drugs . In a study of 10 community pharmacies in which the use of natural products and adverse reactions were explored, it was found that patients who used natural supplements together with their prescribed medications had a 6.4 times higher risk of experiencing adverse reactions than did those patients taking only their prescribed medication (OR; 95 CI, P < 0.001) . Furthermore, a systematic review from Alsanad et al .…”

“…[26,28,31] In a study of 10 community pharmacies in which the use of natural products and adverse reactions were explored, it was found that patients who used natural supplements together with their prescribed medications had a 6.4 times higher risk of experiencing adverse reactions than did those patients taking only their prescribed medication (OR; 95 CI, P < 0.001). [32] Furthermore, a systematic review from Alsanad et al [21] identified 167 theoretical interactions among the 433 participating patients with cancer taking supplements. Risk is aggravated by the fact that the decision about whether to use herbals is not always based on evidenced indications; in addition, patients tend to use various herbals simultaneously, which adds yet another element of risk.…”

Melatonin Interaction Resulting in Severe Sedation

“…Detailed methods have been presented previously (9,10) In brief, adverse events were identified in a community pharmacy where participating pharmacists and pharmacy staff were systematically asking patients collecting prescriptions for conventional medicines whether they had recently been taking NHPs such as herbal medicines, vitamins, minerals or other supplements together with prescription medications and whether they had experienced an unwanted or unexpected effect. Where adverse events were identified, the study team then obtained informed written consent from the patient prior to an in-depth guided telephone interview.…”

“…A formidable challenge for pharmacovigilance of NHPs is the under-reporting of suspected adverse drug reactions associated with these products (7,8). The Pharmacy Study Of Natural health product Adverse Reactions (SONAR) is a multi-centre study assessing the feasibility of a community pharmacy-based active surveillance system to identify adverse reactions related to NHPs (9,10). The study identified a patient who presented with severe sedation after intake of melatonin with two antidepressants (citalopram and nortriptyline) and one opioid analgesic (oxycodone).…”