FWD 2 Expanded Commission E: Kava Kava rhizome (root)

Herbal Medicine: Expanded Commission E

Kava Kava rhizome (root)

Latin Name: Piper methysticum
Pharmacopeial Name: Piperis methystici rhizoma
Other Names: kava, awa

Overview

Kava (also known as kava kava) is the most respected herb in the islands of the South Pacific. It is used as a ritual beverage for ceremonial purposes, including the welcoming of important guests. Pope John Paul II, Queen Elizabeth, President Lyndon B. Johnson, Lady Bird Johnson, and Hillary Rodham Clinton are all known to have drunk kava upon being welcomed to Fiji (the Pope) and Samoa (others) (Singh and Blumenthal, 1997).

Kava has been used in native medicine for its relaxing qualities, for urinary tract infections, asthma (Hope et al., 1993), as a topical anesthetic, and other applications. The primary interest in the West has been its well documented anxiolytic effects.

Numerous clinical studies, including laboratory testing, conducted in Germany reveal the relative safety and efficacy of kava extracts for reduction of symptoms in patients with anxiety disorders (Kinzler et al., 1991; Volz and Kieser, 1997). The results of the clinical studies and the experiences of German patients using kava phytomedicines have shown that kava is an appropriate treatment compared to tricyclic antidepressants and benzodiazepines in anxiety disorders. Kava has also been shown effective for long-term use without the tolerance problems associated with the use of tricyclics and benzodiazepines (Volz and Kieser, 1997).

There is some documentation to support the increased popularity of kava with menopausal women. An eight-week study on a special kava extract (Laitan, W. Schwabe, Germany) resulted in reduction of neurovegetative and psychosomatic dysfunctions (hot flashes, depressive moods, irritability) after only one week of treatment (Warnecke, 1991).

Although usually contraindicated with alcohol, a recent study designed to determine any adverse synergies between the two substances concluded that no negative 'multiplicative' (i.e., synergistic) effects of a special proprietary kava extract (WS 1490) were observed with persons ingesting alcohol (0.05% blood alcohol concentration) (Herberg, 1993).

Other safety concerns with kava deal with the observed yellowing and scaling of the skin in persons using kava beverages heavily for an extended period, a condition known as 'kava dermopathy.' A study (Ruze, 1990) of male kava drinkers in the Tongan Islands concluded that the observed pellagroid dermopathy was not due to niacin deficiency as had previously been suggested.

The general safety of kava was assessed in an industry-sponsored review of the historical and scientific literature, and it was concluded that, 'When used in normal therapeutic doses, kava appears to offer safe and effective anti-anxiety and muscle relaxant actions without depressing centers of higher thought. The safe use of kava as a dietary supplement in cultures that do not have historical experience with its use depends on responsible manufacturing, marketing, individual consumer patterns, and education (Dentali, 1997).

Due to concerns about the relative safety of kava, in September 1997 the American Herbal Products Association recommended the following label warning to all its members: 'Caution: Not for use by persons under the age of 18. If pregnant, nursing, or taking a prescription drug, consult healthcare practitioner prior to use. Do not exceed recommended dosage. Excessive consumption may impair ability to drive or operate heavy equipment' (Anon, 1999). This warning is consistent with cautions published by the Commission E.

German pharmacopeial grade kava kava consists of the peeled and cut dried rhizome of Piper methysticum G. Forster, mostly removed from the root. It must contain not less than 3.5% total kavalactones, calculated as kavain. Botanical identification is confirmed by thin-layer chromatography (TLC), macroscopic and microscopic examinations, as well as organoleptic evaluations including taste, smell, and chewing the rhizome to stimulate salivation and a long lasting anesthetic effect on the tongue (DAC, 19861989).

Description

Kava kava rhizome consists of the dried rhizomes of P. methysticum G. Forster [Fam. Piperaceae], as well as their preparations in effective dosage. The rhizome contains kava pyrones (kawain).

Chemistry and Pharmacology

Kava kava rhizome contains >3.5% kavalactones, a.k.a. kavapyrones, mainly methysticin, dihydromethysticin, kavain, 7,8-dihydrokavain, 5,6-dehydrokavain, 5-6,dehydromethysticin, and yangonin; chalcones, including flavokavains A, B, and C (He et al., 1997). The major kavalactones can be classified into enolides (e.g., 5,6-dihydro-a-pyrones with an asymmetric carbon atom) and dienolides (e.g., achiral a-pyrones) (Hberlein et al., 1997); approximately 3.2% minerals, including potassium (approximately 2.2%), calcium, magnesium, sodium, aluminum, iron; approximately 3.5% amino acids (Leung and Foster, 1996; Mack, 1994).

The Commission E reported anti-anxiety activity for kava kava. In animal experiments a potentiation of narcosis (sedation), as well as anticonvulsive, antispasmodic, and central muscular relaxant effects were described.

The neuropharmacologic effects of kava include analgesia, anesthesia, sedation, and hyporeflexia (Holm et al., 1991; Jamieson et al., 1989; Singh, 1983). Kava affects motor and muscular function (Holm et al., 1991; Jamieson et al., 1989; Meyer, 1962; Singh, 1983), while mental function appears to remain clear (Pfeiffer et al., 1967). Kava pyrones have been shown to protect mice from strychnine-induced convulsions (Klohs et al., 1959). Kava has also been shown to improve seizure control in epileptic patients but with unacceptable skin-yellowing side effects (Pfeiffer et al., 1967).

The mechanism of action by kava on the central nervous system is not clear. In vitro and in vivo studies have produced differing conclusions regarding whether kava binds at GABA receptors. A possible noradrenaline uptake effect has been shown in 3 kavalactones. Anticonvulsant activity may be a result of mediation of Na+ channel receptor sites, common targets of anti-epileptic drugs (Anon, 1998). One of the more interesting features about kava is its ability to relax skeletal muscles, yet it does not act as a central nervous system depressant. Studies show that kava actually helps to retain or increase mental processes (Emser, 1993; Heinze et al., 1994; M nte et al., 1993; Pfeiffer et al., 1967; Saletu et al., 1989).

Uses

Commission E approved kava for use in conditions of nervous anxiety, stress, and restlessness.

Clinical trials have also studied the use of kava for cognitive enhancement (Emser, 1993; Heinze et al., 1994; M nte et al., 1993; Saletu et al., 1989) and climacteric symptom reduction (Warnecke, 1991).

Contraindications

Endogenous depression.

Side Effects

None known.

Note: Extended continuous intake can cause a temporary yellow discoloration of skin, hair, and nails. In this case, application of this preparation must be discontinued. In rare cases, allergic skin reactions can occur. Also, accommodative disturbances, such as enlargement of the pupils and disturbances of the oculomotor equilibrium, have been described.

Use During Pregnancy and Lactation

Not recommended.

Interactions with Other Drugs

Potentiation of effectiveness is possible for substances acting on the central nervous system, such as alcohol, barbiturates, and psychopharmacological agents.

Dosage and Administration

Unless otherwise prescribed: 1.7-3.4 g per day of cut rhizome and other galenical preparations for oral use, equivalent to 60-120 mg kava pyrones. Do not exceed recommended dose.

Note: The equivalency of 1.7-3.4 g dry rhizome to 60-120 mg kava pyrones is based on the drug codex requirement of minimum 3.5% (35 mg/g) kava pyrones content in the raw material.

Cold macerate: Soak 1.7-3.4 g of ground rhizome in 150 ml cold water for several hours, then strain.

Dried rhizome: 1.5-3 g, in divided doses throughout the day (Bone, 1993-1994; Burgess, 1998); 2-4 g (Karnick, 1994).

Note: The rhizome needs to be chewed well and suffiently mixed with saliva while ingesting (Alschuler, 1998).

Fluidextract 1:2 (g/ml): 3-6 ml, in divided doses (Alschuler, 1998; Bone, 1993-1994; Burgess, 1998).

Dry normalized extract containing 30% (300 mg/g) kava pyrones: 0.2-0.4 g (200-400 mg).

Soft native extract containing approximately 55% (550 mg/g) kava pyrones: 0.1-0.2 g (100-200 mg).

Note: The traditional kava preparation in a single dose is reported to deliver approximately 250-300 mg of active a-pyrones (Dentali, 1997).

Duration of administration: Not more than 3 months without medical advice.

Note: Even when administered within its prescribed dosages, this herb may adversely affect motor reflexes and judgment for driving and/or operating heavy machinery.

References

Alschuler, L. 1998. Kava: an herb for our hectic times. Nature's Impact by Impact Communications, Inc.

Anon. 1999. AHPA's Recommended Label Language for Kava Products. HerbalGram 45.

Anon. 1998. Monograph: Piper methysticum (kava kava). Alt Med Rev 3(6):458460.

Bone, K. 19931994. Kavaa safe herbal treatment for anxiety. Brit J Phytother 3(4):147153.

Burgess, N. 1998. Regulatory issues on Piper methysticum (kava). Aust J Med Herbalism 10(1):23.

Dentali, S.J. 1997. Herb Safety Review: Kava, PipermethysticumForster f. (Piperaceae). Bethesda, MD: American Herbal Products Association.

Deutscher Arzneimittel-Codex, 1st suppl. (DAC). 19861989. Stuttgart: Deutscher Apotheker Verlag. K-155:16.

Emser, W. 1993. Phytotherapy of insomniaa critical overview. Pharmacopsychiatry 26:150.

Hberlein, H., G. Boonen, M.A. Beck. 1997. Piper methysticum: enantiomeric separation of kavapyrones by high performance liquid chromatography. Planta Med 63:6365.

He, X., L. Lin, L. Lian. 1997. Electrospray high performance liquid chromatography-mass spectrometry in phytochemical analysis of kava (Piper methysticum) extract. Planta Med 63:7074.

Heinze, H.J., T.F. Munthe, J. Steitz, M. Matzke. 1994. Pharmacopsychological effects of oxazepam and kava-extract in a visual search paradigm assessed with event-related potentials. Pharmacopsychiatry 27(6):224230.

Herberg, K.W. 1993. [Effect of kava-special extract WS 1490 combined with ethyl alcohol on safety-relevant performance parameters] [In German]. Blutalkohol 30(2):96105.

Holm, E. et al. 1991. Untersuchungen zum Wirkungsprofil von D, L-Kavain. Arzneimforsch/Drug Res 41(7):673683.

Hope, B.E., D.B. Massey, G. Fournier-Massey. 1993. Hawaiian materia medica for asthma. Hawaii Med J 52(6):160166.

Jamieson, D.D., P.H. Duffield, D. Cheng, A.M. Duffield. 1989. Comparison of the central nervous system activity of the aqueous and lipid extract of kava (Piper methysticum). Arch Int Pharmacodyn Ther 301:6680.

Karnick, C.R. 1994. Pharmacopoeial Standards of Herbal Plants, Vol. 2. Delhi: Sri Satguru Publications. 79.

Kinzler, E., J. Kromer, E. Lehmann. 1991. [Effect of a special kava extract in patients with anxiety-, tension-, and excitation states of non-psychotic genesis. Double blind study with placebos over four weeks] [In German]. Arzneimforsch 41(6):584588.

Klohs, M.W.F. et al. 1959. A chemical and pharmacological investigation of Piper methysticum Forst. J Med Pharm Chem 1:9599.

Leung, A.Y. and S. Foster. 1996. Encyclopedia of Common Natural Ingredients Used in Food, Drugs, and Cosmetics, 2nd ed. New York: John Wiley & Sons, Inc. 330331.

Mack, R. 1994. Kava kava. Piper methysticuma unique economic plant of the Pacific Islands. J Health Sci 1(1):4348.

Meyer, H.J. 1962. Pharmakologie der Wirksamen Prinzipien de Kawa-rhizoms (Piper methysticum Forst.) Arch Int Pharmacodyn Ther 138:505536.

M nte, T.F. et al. 1993. Effects of oxazepam and an extract of kava roots (Piper methysticum) on event-related potentials in a word recognition task. Neuropsychobiology 27(1):4653.

Pfeiffer, C.C., H.G. Murphree, L. Goldstein. 1967. Effects of kava in normal subjects and patients. Ethnopharmacologic search for psychoactive drugs: Proceedings of a symposium held in San Francisco, California. January 2830. Public Health Service Publication No. 1645:155161.

Ruze, P. 1990. Kava-induced dermopathy: a niacin deficiency? Lancet 335(8703):14421445.

Saletu, B. et al. 1989. EEG-brain mapping, psychometric and psychophysiological studies on central effects of kavaina kava plant derivative. Hum Psychopharmacol 4:169190.

Singh, Y.N. 1983. Effects of kava on neuromuscular transmission and muscle contractility. J Ethnopharmacol 7(3):267276.

Singh, Y.N. and M. Blumenthal. 1997. KavaAn Overview. HerbalGram 39:3356.

Volz, H.P. and M. Kieser. 1997. Kava-kava extract WS 1490 versus placebo in anxiety disordersA randomized placebo controlled 25-week outpatient trial. Pharmacopsychiatry 30(1):15.

Warnecke, G. 1991. [Psychosomatic dysfunction in the female climacteric. Clinical effectiveness and tolerance of Kava Extract WS 1490] [In German]. Fortschr Med 109(4):119122.

Additional Resources

Frater, A.S. 1976. Medical aspects of yaqona. Fiji Med J 4:526530.

Lebot, V., M. Merlin, L. Lindstrom. 1992. Kava: the Pacific Drug. New Haven: Yale University Press.

Lebot, V. and P. Cabalion. 1988. Kavas of Vanuatu: Cultivars of Piper Methysticum Forst. Technical Paper No. 1955. Noumea, New Caledonia: South Pacific Commission. 353.

Lebot, V. and J. Levesque. 1989. The origin and distribution of kava (Piper methysticum Forst. f., Piperaceae): a phytochemical approach. Allertonia 5:223281.

Lehmann, E. et al. 1996. [Effects of a special Kava extract (Piper methysticum) in patients with states of anxiety, tension and excitedness of non-mental originA double blind placebo controlled study of four weeks treatment] [In German]. Phytomedicine 3(2):113119.

Lindenberg, Von D. and H. Pitule-Schodel. 1990. D,L-Kavain in comparison with oxazepam in anxiety states. Double-blind clinical trial. Forschr Med 108(2):4950; 5354.

McGuffin, M., C. Hobbs, R. Upton, A. Goldberg. 1997. American Herbal Product Association's Botanical Safety Handbook. Boca Raton: CRC Press.

Russell, P.N., D. Bakker, N.N. Singh. 1987. The effects of kava on alerting and speed of access of information from long-term memory. Bull Psychonomic Society 25:236237.

Shulgin, A.T. 1973. The narcotic pepper: the chemistry and pharmacology of Piper methysticum and related species. Bulletin on Narcotics 25:5974.

Singh, Y.N. 1992. KavaAn Overview. J Ethnopharmacol 37(1):1345.

Smith, RM. 1979. Pipermethystine: a novel pyridone alkaloid from Piper methysticum. Tetrahedron Lett 35:437439.

Titcomb, M. 1948. Kava in Hawaii. J Polynesian Society 57:105171.

This material was adapted from The Complete German Commission E MonographsTherapeutic Guide to Herbal Medicines. M. Blumenthal, W.R. Busse, A. Goldberg, J. Gruenwald, T. Hall, C.W. Riggins, R.S. Rister (eds.) S. Klein and R.S. Rister (trans.). 1998. Austin: American Botanical Council; Boston: Integrative Medicine Communications.

1) The Overview section is new information.

2) Description, Chemistry and Pharmacology, Uses, Contraindications, Side Effects, Interactions with Other Drugs, and Dosage sections have been drawn from the original work. Additional information has been added in some or all of these sections, as noted with references.

3) The dosage for equivalent preparations (tea infusion, fluidextract, and tincture) have been provided based on the following example:

  • Unless otherwise prescribed: 2 g per day of [powdered, crushed, cut or whole] [plant part]
  • Infusion: 2 g in 150 ml of water
  • Fluidextract 1:1 (g/ml): 2 ml
  • Tincture 1:5 (g/ml): 10 ml

4) The References and Additional Resources sections are new sections. Additional Resources are not cited in the monograph but are included for research purposes.

This monograph, published by the Commission E in 1994, was modified based on new scientific research. It contains more extensive pharmacological and therapeutic information taken directly from the Commission E.

Excerpt from Herbal Medicine: Expanded Commission E Monographs
Copyright 2000 American Botanical Council
Published by Integrative Medicine Communications
Available from the American Botanical Council.