Active Ingredients. - The active ingredient of pareira is now pretty well ascertained to be nothing more or less than buxine, C18H11NO3, an alkaloid which will be found mentioned as entering into the composition of plants of two other families (Lauraceae and Euphorbiaceae), besides being present in various species of Cissampelos, and, probably, some other plants of the order Menispermaceae. Buxine, discovered by Faure in box bark, is substantially identical with the bibirine which was found by Rodie, Maclagan, and Tilly in the "Bibiru" tree, and the pelosin, discovered by Wiggers in pareira.

Buxine, when pure, is a white amorphous substance, which loses 8.2 per cent. of water when heated to 212° Fahr. It has a strong and clinging bitter taste, and a marked alkaline reaction; is very insoluble in water, freely soluble in absolute alcohol and in ether, remarkably soluble in chloroform and acetone. It completely neutralizes acids, and forms uncrystallizable salts with them. Concentrated sulphuric acid changes it to a brownish-yellow resinoid body.

Physiological Action. - The root of C. Pareira is a well-known tonic and diuretic, exerting a specific influence over the mucous membrane which lines the various passages. What are the effects produced upon the system in general does not appear to be well known, though, in large doses, it would seem certain that pareira is aperient.

Therapeutic Action. - The use of pareira at the present day is almost limited to the cure of discharges from the urino-genital mucous membrane. Gonorrhoea, leucorrhoea, and chronic inflammation of the bladder are successfully treated with it. In the last-named disease Sir B. Brodie considers pareira superior to uva-ursi. It lessens, he tells us, the secretion of the ropy mucus, and appears, at the same time, to diminish the inflammation and the irritability of the organ.

Preparations And Dose. - The best form (Phillips) for the administration of pareira is the decoction (B. Ph.), to which may be added, as occasion renders desirable, alkaloids, acids, or narcotics, especially hyoscyamus. The officinal preparations are: Extract. Pareirae Flui-dum, 3 ss. - j. (2. - 4); Infus. Pareirae, 3 j. - ij. (30. - 60.)