Source, Etc

The drug formerly official in the British Pharmacopoeia under the name Pareira Root is derived from Chondrodendron tomentosum, Ruiz and Pavon (N.O. Menispermaceoe), a climbing plant with a stout woody stem, growing to a considerable height. It is a native of Peru and Brazil, and is regarded by the Brazilians as a valuable medicine. Its botanical origin remained long in an obscurity that was increased by Linnaeus, who founded a species of Cissampelos (C. Pareira) and quoted it as the source of Pareira brava.

Description

True Pareira brava occurs in long, woody, nearly cylindrical pieces averaging 2 to 4 cm. in diameter, but attaining 5 cm. or even more. It is nearly black in colour, tortuous and knotty, and marked externally with longitudinal furrows and transverse ridges and fissures. It is hard and heavy, breaking with a coarsely fibrous fracture; internally it is yellowish or brownish grey. The fractured root, when cut with a knife, exhibits a glossy, waxy, rather than woody surface. The transverse section shows four or five crenate, concentric or more or less eccentric zones, separated from each other by lighter lines of parenchymatous tissue. Each zone consists of a varying number of wedge-shaped wood-bundles with large pores alternating with wide medullary rays. A similar abnormal structure is found in many Menispermaceous stems and roots. The innermost zone is usually from 6 to 12 mm. in diameter.

The drug has no odour, but a decidedly bitter taste.

The student should observe

(a) The nearly black outer surface,

(b) The crenate outline of the zones,

(c) The waxy cut,

(d) The bitter taste.

Constituents

Pareira brava contains about 2.5 per cent, of beberine (compare bebeeru bark, p. 273), to which its bitter taste is due; to this alkaloid the name pelo-sine (derived from Cis-sampelos) was given until its identity with beberine was proved. An unusually large quantity (about 9 per cent), of fatty acids, chiefly stearic, is said to be present, but this statement requires confirmation. Other constituents are an amorphous alkaloid (chondrodine), tannin and starch. The genuine drug yields about 12 per cent. of (cold) aqueous extract and about 4 per cent. of ash. Spurious Pareira brava often yields much less aqueous extract (see below). According to Fattis, in addition to beberine, which is soluble in benzene, two other alkaloids insoluble in benzene, one crystalline, the other amorphous, are present.

Uses

Pareira brava is used in inflammatory affections of the urinary tract; it is considered to relieve pain and promote healing and cessation of muco-purulent discharge. It is not much used now, owing possibly to the substitution of other roots for the genuine drug.

Fig. 151.   True Pareira Brava. Portion of a root, and transverse sections. (Bentley, after Hanbury.)

Fig. 151. - True Pareira Brava. Portion of a root, and transverse sections. (Bentley, after Hanbury).

Varieties And Substitutes

Genuine Pareira brava appears at uncertain intervals on the London market. Its place has for some years been frequently taken by the root of a Menispermaceous plant of unknown botanical origin. This, the common substitute, may be distinguished by its distinctly brownish colour, the larger number of narrower zones which are not distinctly crenate, the larger vessels in the wood, and the less bitter taste. The drug is, further, not so heavy as true Pareira brava, and does not exhibit, when cut transversely, the same waxy nature. In addition to the above differences this false Pareira contains scarcely any fat, yields less ash (about 1.3 per cent.), and less aqueous extract (about 6 percent.).

Occasionally the stems of the plant are mixed with true Pareira brava; these are paler in colour, frequently bear the minute apothecia of lichens, and exhibit a small pith.

Other substitutes have occurred, and are likely to occur; it is essential therefore, in this as in all cases, that the student should make himself familiar with the characters of the true drug, so as to be able to distinguish it from any substitute that may occur at any time.