HEALTH SERVICE RESEARCH POSTER PRESENTATION ABSTRACTS
Please note: All posters will be displayed in
Salons 10-12.
THURSDAY, 5:30-6:15 PM
Vik SA, Hanley DA, Patten SB, Verhoef M, Brasher P,
Hopman W, Anastassiades T, Tanveer T.
A preliminary assessment of potential drug-herb interactions
in a Canadian population-based study
University of Calgary savik@ucalgary.ca
PURPOSE: To assess the prevalence of selected
potential drug-herb interactions among Canadian Multicentre Osteoporosis
participants.
METHODS: Subjects were participants in the Canadian
Multicentre Osteoporosis Study (CaMos), a prospective cohort study,
evaluating prevalence, incidence and determinants of osteoporosis. Participants
were recruited to the study in 1995 from an age-sex stratified random
sample of non-institutionalized persons aged >25 years, living within
50 kilometres of one of the nine CaMos study centers. The present analysis
is restricted to data collected between 2001-2002, during the 5-year
follow-up interviews. Potential drug-herb interactions were selected
based on review articles and a recently published book that provided
an assessment of the quality of the evidence or clinical impact of drug-herb
interactions. The specific criteria included: type of study (e.g. clinical
trials versus case reports), report reliability, biological plausibility
and the clinical significance of interactions. In this preliminary analysis,
the proportion of subjects at-risk for potentially dangerous drug-herb
interactions is reported for subjects using the selected cardiovascular
(digoxin, furosemide and warfarin) and neuroleptic agents (alprazolam,
levodopa, lithium, phenelzine and selective seratonin reuptake inhibitors).
The concomitant use of St. John's Wort with cyclosporin, spironolactone
or venlafaxine was also examined.
RESULTS: At 5-years, 7652 (81 %) of the original
9423 cohort participants were remaining. The average age was 70 years
(range 31-99) and 70% were female. Of the 7652, 1069 (14%) were taking
at least one of the prescription medications for which drug-herb interactions
were assessed. In total, only 14 (1.3%) of the 1069 participants were
using at least one contraindicated drug-herb combination. Of the 514
subjects on one of the cardiovascular medications, 13 (2.5%) were concomitantly
using a contraindicated herb. Only one of the 514 subjects taking a
neuroleptic agent was identified as at-risk for a potential drug-herb
interaction (lithium and psyllium). No subjects were concomitantly using
the potentially dangerous combination of St. John's Wort with cyclosporin,
spironolactone or venlafaxine.
CONCLUSIONS: Concerns regarding interactions
between herbal supplements and prescribed medications have been the
subject of much speculation, and previous studies have been limited
to convenience samples, primarily on older adults. In this randomly
selected, population-based sample we found a relatively low rate of
potential drug-herb interactions, most of which were among subjects
using specific cardiovascular medications.
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