HERBAL MONOGRAPHS KAVA KAVA/443Kava Kava
Piper methysticum
TRADE NAMES
Kava Kava (available from numerous manfacturers) Alcohol
Free Kava Kava, Kava Kava Power, Kava Kava Premium,
Kava Kava Root
DESCRIPTION
Medicinal Parts: The medicinal parts are the peeled, dried,
cut rhizome, which has normally been freed from the roots,
and the fresh rhizome with the roots.
Flower and Fruit: The plant has numerous small flowers in
spike-like inflorescences 3 to 9 cm long.
Leaves, Stem and Root: The plant is a 2 to 3 m high, erect
dioecious bush. The leaves are very large, measuring 13 to
28 cm by 10 to 22 cm. They have a deeply cordate base and
9 to 13 main ribs that are slightly soft on the undersurface.
The stipules are large. The plant has a massive, 2 to 10 kg,
branched and very juicy rhizome with many roots. They are
blackish-gray on the outside and whitish on the inside. The
fracture is mealy and somewhat splintery. The central
portion is porous with irregularly twisted thin woody
bundles, separated by broad medullary rays, forming meshes
beneath the bark.
Characteristics: The taste is pungent and numbing, and the
odor is reminiscent of lilac.
Habitat: The plant is indigenous to the South Sea Islands and
is mainly cultivated there.
Production: Kava Kava rhizome consists of the dried
rhizomes of Piper methysticum.
Other Names: Ava, Ava Pepper, Intoxicating Pepper, Kawa,
Kawa Pepper, Tonga, Kew
ACTIONS AND PHARMACOLOGY
COMPOUNDS
Kava lactones (kava pyrones, 5-12%): chief components
include (+)-kavain, dihydrokavain (marindinine), (+)-meth-
ysticin, dihydromethysticin, yangonine, desmethoxy-
yangoninChalcones: including flavokavin A and B
EFFECTS
The kava pyrones in the drug have centrally muscle-relaxing,
anticonvulsive and antispasmodic effects. The herb also
contains hypnotic/sedative, analgesic and psychotropic prop-
erties contributing to its use for anxiety and insomnia.
The centrally muscle-relaxing, analgesic and anticonvulsive
action of the kava pyrones, kavain, dihydrokavain, dihydro-
methysticin and (+/-) kavain (synthetic kava pyrone) is
attributed to the interaction with ion channels. The interac-
tion consists of fast and specific inhibition of voltage-
dependent sodium channels and reduction of currents
through voltage-activated sodium and calcium channels
(Friese, 1998; Gleitz, 1995; Gleitz, 1996; Schirrmacher,
1999). The paralysis effect of Kava on neuromuscular
transmission and muscle contractility is similar to that of
local anesthetics (Jameison, 1989; Singh, 1983). The lipid
soluble extract (kava resin) decreases spontaneous motility
and motor control (Jamieson, 1989).The analgesic action of kavain, dihydrokavain, methysticin
and dihydromethysticin is due to antinociceptive activities.
Nalaxone (opiate antagonist) is ineffective in reversing the
antinociceptive activities, thus indicating the analgesia pro-
duced from the compounds occurs via non-opiate pathways
(Jameison, 1990; Jameison, 1989).The lipid soluble components of kava do not interact with
benzodiazepine binding sites, but do seem to potentiate the
activity of GABA-A in the brain center for sedative effects
(Davies, 1992; Jussofie, 1994). The psychotropic properties
of Kava have been demonstrated by the inhibition of
norepinephrine uptake by kavain, dihydromethysticin and the
racemate (+/-) kavain (Seitz, 1997). One study did find that
desmethoxyyangonin, methysticin, yangonin, dihydrometh-
ysticin, kihydrokavain and kavain reversibly inhibit MAO-B
(Uebelhack, 1998). An increase of dopamine and serotonin
by activation of neurons results in central nervous system
effects (Fachinfo Antares 120(R), 1996).A recent study investigated the antithrombotic activity of
kava pyrones. Kavain exerts antithrombotic action on human
platelets through the inhibition of cyclooxygenase (COX) as
a primary target. This suppresses the generation of throm-
boxane (TXA2), which normally induces aggregation of
platelets and exocytosis of ATP by its binding on TXA2
receptors (Gleitz, 1997).CLINICAL TRIALS
A randomized, double-blind, placebo-controlled study was
conducted with 101 outpatients suffering from anxiety of
non-psychotic origin who met DSM-IH-R criteria. Improve-
ments in anxiety were seen after week 8 with a standardized
Kava Kava extract (70% kava-pyrone). The study continued
over a 25-week period with significant improvement based
upon the Hamilton Anxiety Scale (HAMA), somatic and
psychic anxiety, Clinical Global Impression, Self-Report
Symptom Inventory and Adjective Mood Scale (Volz, 1997).The anxiolytic effect of a special kava extract (70 mg of kava
pyrones three times daily) was compared to two benzodiaze-
pine preparations (oxazepam 15mg/day, bromazepam). The
multi-center, double-blind study involved 172 patients.
There was a therapeutically relevant reduction in the severity