RHUBARB 409 



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 enormous doses. It Is sometimes prescribed with aloes. Plienolphthalein is elimi- 

 nated chiefly by the intestines. It is the common constituent of candy cathartics. 



Doae. — H., 3i-3iss, (4-6) ; dogs, gr.ii-x, (0.12-0.6) ; puppies and cats, gr.ss-ii, 

 (0.03-0.12). 



Phenolplithalein may be given to horses with food. To dogs and cats it is 

 given in capsule, or tablets with chocolate (Thaletts, Mulford), or in pill with 

 aloes, strychnine, belladonna and cascara (Phenalos, Mulford). 

 Rheum. Rhubarb. (U. S. P.) 



Synonym. — Rhei radix* B. P.; rhubarbe, Fr. ; rhubarber, G. 



The rhizome and roots of Rheum officinale Baillon, Rheum palmatnm LinnS, 

 and the var. tanguticum Maximowicz (Fam. Polygonacew), or probably other 

 species of Rheum, grown in China and Thibet, deprived of most of the bark and 

 carefully dried. 



Description. — In sub-cylindrical, barrel-shaped, or conical pieces known in 

 commerce as "rounds," or in plano-convex pieces known in commerce as "flats," 

 or in irregularly formed pieces, frequently with perforations. It is hard and 

 moderately heavy ; attaining a length of 17 cm. and a diameter of 10 cm., often 

 cut in pieces of variable form and size; outer surfaces yellowish-brown, mottled, 

 with alternating, longitudinal striae of grayish-white parenchyma and reddish or 

 brownish medullary rays; odor aromatic, characteristic; taste characteristic, 

 slightly bitter and astringent, gritty when chewed and tingeing the saliva yellow. 



The powder is bright orange-yellow to yellowish-brown; becoming red with 

 alkalies; when examined under the microscope it exhibits calcium oxalate. 



Constituents. — 1, the purgative principle which gives the yellow color, a 

 glucoside, chrysarobin (CsoHzoOt), yields 2-3 per cent, of chrysophanic acid 

 (CisHioOi), also called rhein or chrysophan; 2, rheotannic acid (CaoHjoOu), which 

 gives astringency to rhubarb; 3, calcium oxalate (35 per cent.), causing gritti- 

 ness; 4, resinous bodies: phaeoretin, emodin, aporetin and erythroretin. Chryso- 

 phanic acid and the resins are somewhat purgative, but the exact purgative 

 principles have yet to be discovered? 



Dose.— Stomachic— U. & C, 5i-ii, (30-60) ; Sh., 3i, (4) ; D. & Cats, gr.v-x, 

 (.3-.6). 



Mild Purgative. — Foals and Calves, 3i-ii, (4-8) ; D., 3i-ii, (4-8). Fowl, gr.v-vii 

 in pill. , 



PREPARATIONS. 



Fluddextractum Rhei. Fluidextract of Rhubarb. (U. S. P.) 

 Made by maceration and percolation with alcohol and water, and evaporation, 

 so that 1 mil::=l Gm. of the crude drug. 

 Dose. — Same as that of rhubarb. 

 Pulvis Rhei Compositus. Compound Powder of Rhubarb. (U. S. & B. P.) 

 Synonym. — Gregory's powder. Rhubarb, 25; magnesium oxide, 65; ginger, 10. 

 Dose.— Foals and Calves, gss-i, (15-30). 



Extractum Rhei. Extract of Rhubarb. (U. S. & B. P.) 

 Dose.— D., gr.v-x, (.3-.6). 



There are many other oflicial preparations, but they possess no value in 

 veterinary medicine. 



Action Internal. — Alimentary Canal. — Rhubarb is a bitter, and there- 

 fore in small doses improves digestion in all animals by increasing the 

 flow of salivary and gastric juices, and by stimulating the appetite, vas- 

 cularity, and movements of the stomach. It is called a stomachic and 

 bitter tonic. Larger doses cause mild purgation in the case of dogs and 

 cats, but horses and cattle are but slightly affected in this way. The 

 activity of rhubarb is partly due to the solvent action of bile. It is com- 

 monly described as an agent which stimulates peristaltic action, but it is 

 not certainly known how purging is brought about. Secondary constipa- 

 tion is more apt to follow the use of rhubarb than other drugs, because 

 of rheotannic acid. This substance may be absorbed and eliminated into 



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