Complementary Alternative Cardiovascular Medicine

50 Alternative Cardiovascular Medicine
decrease, or increase the action of prescribed drugs, which is especially
important for drugs with narrow therapeutic windows, such as numerous
cardiovascular drugs, and in sensitive patient populations, such as the
elderly, chronically ill, and those with compromised immune systems.
The dramatically increased popularity of herbal products in North
America in the 1990s (1) has led to increased scrutiny of commercial
products for quality and conformity to label claims, as reflected in numerous
analytical surveys sponsored by media and consumer organizations.
Also, recently a plethora of articles in scientific, mainly medical, publications
have appeared addressing the question of herb–drug interactions
(2–4); two books on the topic were published in 1998 from the same
publishing company (5,6). Particular attention has been directed to the
potential for adverse consequences in the treatment of chronic conditions
(7), effected by preoperative herbal use (8), especially regarding
homeostasis (9). Several recent publications have focused on the potential
for adverse effects of herbal medicinals on cardiovascular drugs
(10–12).
Assessment of the potential for adverse consequences, resulting from
either the intrinsic pharmacological effect of botanicals or their influence
on the activity of prescription medications, has been criticized on
mainly two counts. First, many of the reports of herb-induced interactions
are unreliable, because they are based on poorly documented case
reports (2) or theoretical extrapolations from in vitro activity (7); a review
of the published clinical evidence on interactions between herbal and
conventional drugs evaluated 108 cases of suspected interactions and
classified 68.5% as unable to be evaluated, 13% as well-documented,
and 18.5% as possible interactions (13).
Concern over the potential adverse effects of dietary supplements,
and also of some food items, is exacerbated by a conviction in some
regions of the country that the dearth of adverse-event reports may reflect
a combination of underreporting and the pervasive belief of herbal enthusiasts
in the general benignity of natural products (2), with a consequent
lack of causality attribution. Furthermore, it has been expressed that the
likelihood of herb–drug interactions could be higher with herbs than
with prescription drugs, which usually contain single chemical entities,
whereas herbs contain an array of constituents with varied pharmacological
activity (13). It has been highlighted that the potential importance
of herb–drug interactions warrants an increased research effort because
of the paucity of reliable information in this area (14). Herbs, as well as
nutritional items, may influence treatment of patients with cardiac problems
by directly affecting either the cardiovascular system, the absorption,
and/or metabolism of cardiovascular drugs.