The bark of Rhamnus purshiana.

Cascara in small doses is tonic and stomachic; in large dose, laxative or cathartic, with active and certain effect. It sometimes causes griping pain.

Fluidextractum Cascarae Sagradae. Fluid Extract Of Cascara Sagrada

May be given at night, or one or two hours after meals. Average dose, at night, ʒ ss.; after meals,  xv.-1 mil, well diluted. The aromatic fluidextract may be given in twice as large a dose.

Cascara is now used in greater quantity than any other drug in the pharmacopoeia. It is pleasantly laxative and may be used year in and year out without losing its specific effect, and without fear of harm to the individual. Usually ten to twenty drops at night in a little water is the best manner of taking it, but the pellet form is more convenient.