Ginseng (Panax ginseng
and Panax quinquefolius)
Ginseng has been labeled an adaptogen
because it reputedly protects the body against stress and restores homeostasis.[62]
It has been used for virtually every purpose, including to promote health, immune
function, endocrine function, athletic performance, and cognitive function and to
treat cardiovascular disease, diabetes mellitus, cancer, impotence, and viral infections.
[63]
Although ginseng has measurable pharmacologic
activity, compelling evidence to support its use for any specific indication is lacking.
[64]
Other "varieties" of ginseng, such as Siberian
ginseng (Eleutherococcus senticosus) and Brazilian
ginseng (Pfaffia paniculata) are unique plants with
different pharmacologic effects that may nevertheless be included in commercially
available ginseng preparations.
Most pharmacologic effects of ginseng are attributed to the ginsensosides,
a group of compounds known as steroidal saponins that act as steroid hormones. It
is not known, however, whether long-term use of ginseng can cause the well-described
complications of long-term steroid use. The broad but incompletely understood pharmacologic
profile of ginseng can be attributed to the many heterogeneous and sometimes opposing
effects of different ginsenosides.[63]
Actions
on virtually every organ system have been described, but the neuroendocrine and hematologic
effects have the greatest implications for anesthesiologists. Panax
quinquefolius lowers postprandial blood glucose in healthy subjects and
in patients with type 2 diabetes mellitus.[65]
[66]
Although this effect may have therapeutic potential, it may also create unintended
hypoglycemia, particularly in patients fasting preoperatively. Another potential
clinical issue surrounding the use of this herb is its effects on coagulation pathways.
Ginsenosides inhibit platelet aggregation in vitro[67]
[68]
and prolong the thrombin time and activated
partial thromboplastin time in rats.[69]
Results
from one preliminary study suggest that the antiplatelet activity of panaxynol, a
constituent of ginseng, may be irreversible in humans.[70]
Although ginseng may inhibit the coagulation cascade, ginseng use was associated
with a significant decrease in warfarin anticoagulation in one reported case.[71]
The pharmacokinetics of ginsenosides Rg1, Re, and Rb2 have been
investigated in rabbits.[72]
The elimination half-lives
of these three ginsenosides ranged from 0.8 hour for ginsenoside Re to 7.4 hours
for ginsenoside Rb2. These data suggest that patients should discontinue ginseng
use at least 24 hours before surgery, but discontinuation at least 7 days before
surgery is preferred because of the potential for irreversible platelet inhibition.
