Kavae Rhizoma. Br.
"Kava Rhizome is the peeled, dried, and divided rhizome of Piper methysticum, Forst. fil." Br. "The dried rhizome and roots of Piper methysticum Forster (Fam. Piperaceae)" N.F.
Kava, N. F.; Methysticum; Kava-kava.
The genus Piper includes a large number of sub-tropical plants, which are mostly shrubs, and rarely herbs or trees. A number of the species are of great economic importance. Piper methysticum is a shrub, several feet high, indigenous to many of the South Sea Islands. The plant has cordate, acuminate leaves and very short axillary spikes of flowers. The natives prepare a fermented liquor from the upper portion of the rhizome and the base of the stems.
Kava rhizome occurs "in whitish or light brownish-grey irregularly cuboid or roughly wedge-shaped fragments from which the periderm has been sliced off; from one to five centimetres thick. In transverse section, usually exhibiting a central dense pith, surrounded by a distinct ring of narrow, radiating, vascular bundles separated by relatively broad, paler, medullary rays. Fracture starchy. Slight agreeable odor; taste pungent and bitter." Br.
The N. F. description is as follows: "Consisting of a large, irregular knotty crown, often 12 cm. or more in diameter, from which proceed numerous, long, cylindrical, tough, nearly simple roots, which tend to fray out into bare, separated fibro-vascular bundles; the crown soft, light, spongy, and granular and very starchy; externally dark-brown or blackish, the crown frequently partly scraped and light brown to light gray; internally white. Odor faint but characteristic; taste aromatic and pungent, slightly bitter, more or less local anaesthesia resulting. The powdered drug, when examined under the microscope, exhibits numerous, simple, or two- to three-compound starch grains, the individual grains being up to 0.045 mm. in diameter, many with radial clefts or triangular fissures at the center; yellow resin and oil cells; narrow sclerenchymatous fibers with thin, strongly-lignified walls; tracheae with scalariform or reticulate markings, up to 0.15 mm. in width; few nearly isodiametric wood parenchyma from the remains of the stem. Kava yields not more than 8 per cent. of ash." N. F.
The pharmacognosy of this drug has been written up by Semenow in Ap. Ztg., 1890, p. 216, and True, Ph. Rev., xiv, No. 2. Powdered Kava consists of numerous starch grains which are either single or 2- to 3-com-pound, the individual grains having central radial clefts with triangular fissures varying from 0.006 to 0.035 mm. in diameter. The sclerenchymatous fibers have thin walls which are strongly lignified. The tracheae have scalariform or reticulate markings. The oil cells frequently contain a yellowish resin. The drug should not yield more than 8 per cent. of ash.
Gobley isolated from kava root a crystalline principle (analogous to piperin), methysticin, or kavahin, which is without odor and taste, and is probably inert. (J. P. C., Jan., 1860.) It possesses the formula C15H14O5. and is the methyl ester of p-piperonyl acetic acid, and when purified forms silky, lustrous needles melting at 138° to 139° C. (280.4°-282.2° F.). Kavahin differs from piperin and cubebin in being colored red by hydrochloric acid, the red color fading on exposure to air into a bright yellow, and in being colored by strong sulphuric acid a purplish violet, which passes into green. In 1844 Morson discovered an active principle, kawine. This is a greenish-yellow, strongly aromatic and acrid resin. It was again studied by Cuzaut in 1860, and by Lewin in 1886. This latter investigator separates it into two resins, of which the b-resin is greasy and of a reddish-brown color, appearing in mass almost black. This is less active than the a-resin, which is yellowish-brown, has the characteristic odor of the drug, is freely soluble in alcohol, and placed upon the tongue produces a burning sensation followed by local anesthesia. (A. J. P., 1886, 450.) Yangonin is another glucoside which has been studied by Borsche and Gerhardt. (Riedels Archives, 1914, 50.) A volatile oil has also been found in the root. (J. P. C., March, 1862.) Lavialle (L'Union Pharm., Jan., 1889) claims to have obtained an alkaloid, kavaine. (See also Proc. A. Ph. A., 1897, 564.)
Uses.—Under the names of Ava or Kava the natives of the Sandwich Islands have used as an intoxicant a beverage prepared from kava rhizome. The intoxication is wholly unlike that caused by alcohol, being of a silent and drowsy character, accompanied by incoherent dreams, with great loss of muscular power, which is probably due to the action of kava resin upon the spinal cord.
The physiological action of kava and its resin has been investigated by L. Lewin (Piper Methysticum, Berlin, 1886), and David Cerna (T. G., 1891). The phenomena which follow the hypodermic injection of the fluidextract of kava or of a solution of its resin are, anesthesia at the point of injection, followed, after absorption, by general paralysis, due to a direct action on the motor side of the spinal cord; the motor nerves and the muscles remain intact. The local anesthesia is due to a paralysis of the sensory nerve filaments, and when the resin is brought in contact with the mucous membranes there is a burning pain, followed in time by a complete loss of sensibility, which is remarkably permanent, since Lewin found that from six to seven minims of a solution of kava injected beneath the skin produced a complete loss of sensibility in the surrounding area, which did not pass away for eight days. (D. M. Ztg., Feb., 1886.) The action of the drug upon the circulation is subordinate to its nervous influence, but according to the experiments of Cerna it does stimulate the heart, although it decreases the number of pulsations by stimulating the inhibitory nerve centers. The same investigator found that at first it stimulates, afterwards depresses, and finally paralyzes the respiratory center. The insolubility and irritant action of kava resin has lessened its use as a practical local anesthetic.
As long ago as 1857 kava root was employed in the treatment of gonorrhea, and there is much testimony to its value both in the acute and the chronic form of the disease, as well as in vaginitis, leucorrhea, nocturnal incontinence, and similar conditions of the genito-urinary tract.
Under the name of gonosan a twenty per cent. solution of kava resin in oil of sandalwood is used internally in the treatment of gonorrhea. The advantages claimed for it are that it is much less likely to disturb the stomach than sandalwood oil, that it is locally anesthetic and hence relieves the pain and, apparently, also has some anaphrodisiac action. According to Ganz (All. M. C. Z., 1906, p. 213), while not of itself gonocidal it renders the urine permanently antiseptic and so deprives the gonococci of conditions favorable for their growth. The preparation is marketed in capsules containing 0.3 Gm. of which two to four may be given several times a day. (For the methods of determining kava resins in this and similar preparations, see Ph. Ztg., 1914, 284.)
Dose, of kava rhizome, from fifteen to forty-five grains (1-3 Gm.).
Off. Prep.—Extractum Kavae Liquidum, Br., (N. F.).
The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.