Drugs and Chemicals of
Concern > Kava (Other Names:
Ava, Intoxicating Pepper, Kawa Kawa, Kew, Sakau, Tonga, Yangona)
Kava
(Other Names: Ava, Intoxicating Pepper, Kawa Kawa, Kew,
Sakau, Tonga, Yangona)
May 2008
DEA/OD/ODE
Introduction:
Kava, also known as Piper methysticum
(intoxicating pepper), is a perennial shrub native to the South Pacific
Islands, including Hawaii. This relatively slow growing plant is harvested for
its rootstock, which contains the pharmacologically active compounds
kavalactones.
The term kava also refers to the
non-fermented, psychoactive beverage prepared from the rootstock. For many
centuries, Pacific Island societies have consumed kava beverages for social,
ceremonial, and medical purposes. Traditionally, kava beverages are prepared
by chewing or pounding the rootstock to produce a cloudy, milky pulp that is
then soaked in water before the liquid is filtered to drink.
Kava-containing dietary supplements are marketed in the
U.S. for the treatment of anxiety and insomnia. There is also an increasing
use of kava for recreational purposes. The reinforcing effects of kava include
mild euphoria, muscle relaxation, sedation, and analgesia. Currently, kava is
not controlled under the federal Controlled Substances Act (CSA).
Licit Uses:
In the U.S., kava is sold as dietary
supplements promoted as natural alternatives to anti-anxiety drugs and
sleeping pills. A meta-analysis of six randomized, placebo-controlled,
double-blind kava clinical trials found that kava (60-200 mg of
kavalactones/day) produced a significant reduction in anxiety compared to
placebo. However, the FDA has not made a determination about the ability of
dietary supplements containing kava to provide such benefits.
Kava dietary supplements are commonly
formulated as tablets and capsules (30-90 percent kavalactones;
50-250 mg per capsule). Kava is also available as whole root, powdered
root, extracts (powder, paste, and liquid), tea bags, and instant powdered
drink mix. Kava is frequently found in products containing a variety of herbs
or vitamins, or both.
A number of cases of liver damage
(hepatitis and cirrhosis), and liver failure have been associated with
commercial extract preparations of kava. In 2002, the FDA issued an advisory
alerting consumers and healthcare providers to the potential risk of liver
related injuries associated with the use a kava dietary supplements.
Chemistry and Pharmacology:
The pharmacologically active
kavalactones are found in the lipid soluble resin of the kava rootstock. Of
the 18 isolated and identified, yangonin, methysticin, dihydromethysticin,
dihydrokawain, kawain, and desmethoxyyangoin are the six major kavalactones.
Different varieties of kava plants possess varying concentrations of the
kavalactones.
The pharmacokinetics of the kavalactones
has not been extensively studied. Kavalactones are thought to be relatively
quickly absorbed in the gut. There may be differences in the bioavailability
between the different kavalactones.
The limbic structures, amygdala complex,
and reticular formation of the brain appear to be the preferential sites of
action of kavalactones. However, the exact molecular mechanisms of action are
not clear.
Kava has the potential for causing drug
interactions through the inhibition of CYP450 enzymes that are responsible for
the metabolism of many pharmaceutical agents and other herbal remedies.
Chronic use of kava in large quantities may cause a dry scaly skin or yellow
skin discoloration known as kava dermopathy. It may also cause liver toxicity,
and extrapyramidal effects (e.g., tremor and abnormal body movement). The
National Toxicology Program is currently conducting toxicology studies of the
kava extract.
Individuals may experience a numbing or
tingling of the mouth upon drinking kava due to its local anesthetic action.
High doses of kavalactones can also produce CNS depressant effects (e.g.,
sedation and muscle weakness) that appear to be transient.
Illicit Uses:
Information on the illicit use of kava
in the U.S. is anecdotal. Based on information on the Internet, kava is being
used recreationally to relax the body and achieve a mild euphoria. It is
typically consumed as a beverage made from dried kava root powder, flavored
and unflavored powdered extracts, and liquid extract dissolved in pure grain
alcohol and vegetable glycerin. Individuals may consume 25 grams of
kavalactones, which is about 125 times the daily dose in kava dietary
supplements.
Intoxicated individuals typically have
sensible thought processes and comprehensive conversations, but have
difficulty coordinating movement and often fall asleep. Kava users do not
exhibit the generalized confusion and delirium that occurs with high levels of
alcohol intoxication. However, while kava alone does not produce the motor and
cognitive impairments caused by alcohol, kava does potentiate both the
perceived and measured impairment produced by alcohol alone.
User Population:
Information on user population in the
U.S. is very limited. Kava use is not monitored by any national drug abuse
surveys.
In the 1980s, kava was introduced to
Australian Aboriginal communities where it quickly became a drug of abuse. It
has become a serious social problem in regions of Northern Australia.
Distribution:
Kava is widely available on the
Internet. Some websites promoting and selling kava products also sell other
uncontrolled psychoactive products such as Salvia divinorum and kratom.
Several kava bars and lounges in the U.S. sell kava drinks.
Control Status:
Kava is not a controlled substance in
the U.S. Due to concerns of liver toxicity, many countries including
Australia, Canada, France, Germany, Malaysia, Singapore, Switzerland, and the
United Kingdom have placed regulatory controls on kava. These controls range
from warning consumers of the dangers of taking kava to removing kava products
from the marketplace.
Comments and additional information are welcomed by the
Drug and Chemical Evaluation Section, FAX 202-353-1263 or telephone
202-307-7183.
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