Kava rhizome, or Kava-kava, is obtained from Piper methysticum, Forster (N.O. Piperaceae), a shrub indigenous to, the Sandwich Islands. For medicinal use the periderm and roots are removed from the rhizome, which is then cut longitudinally or transversely into irregular pieces and dried. The rhizome occurs in white or pale greyish-brown, irregularly cubical or wedge-shaped pieces, which vary from 1 to 5 centimetres or more in thickness, and are more or less porous in texture. A transverse section exhibits a dense central pith, surrounded by a ring of narrow, radiating, vascular bundles, separated by medullary rays. The rhizome breaks with a starchy fracture. It has a slight, rather pleasant odour, and a pungent, bitter taste.
Constituents.—The active constituents of the drug appear to be two resins, α-kava and β-kava resins. In addition to these the drug contains methysticin, φ-methysticin, and yangonin, together with abundance (50 per cent.) of starch. An alkaloid, kavaine, is also said to be present.
Action and Uses.—Kava rhizome is official in the Australian Colonies. It resembles pepper in its local action, and is employed medicinally as an antiseptic and diuretic in gonorrhoea and cystitis. A liquid extract is prepared for use in mixture form with bladder sedatives and diuretics; by removal of the spirit from the liquid extract, a solid extract is obtained, which is given in capsules with oil of sandal wood, in gonorrhoea and catarrhal conditions of the genito-urinary organs. It is used in the South Sea Islands for preparing an intoxicating drink; the intoxication is said to affect the power of movement, while leaving the intellect clear.
- Extractum Kavae, B.P.C.—EXTRACT OF KAVA.
- This solid extract is given in pills. Dose.—6 to 30 centigrams (1 to 5 grains).
- Extractum Kavae Liquidum, I.C.A.—LIQUID EXTRACT OF KAVA.
- Kava rhizome, in No. 20 powder, 100; alcohol (45 per cent.), a sufficient quantity; alcohol, sufficient to produce 100. Macerate the drug with 200 of alcohol for forty-eight hours, then transfer to a percolator, and allow percolation to proceed, reserving the first 75 of the percolate, and subsequently exhausting the drug by percolation with alcohol (45 per cent.). Recover most of the alcohol from the second percolate by distillation, evaporate the residue at a temperature below 80° to a soft extract, dissolve this in the reserved percolate, and add sufficient alcohol (90 per cent.) to make up to the required volume. Liquid extract of kava is official in the Australasian Colonies. Dose.—2 to 4 mils (30 to 60 minims).
The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.