Radix et Rhizoma Rhei(DaHuang, ´ó»Æ)

Source
The root and rhizome of Rheum palmatum L, R. tanguticum Maxim. ex Balf. or R. officinale Baill., family Polygonaceae.
Characteristics
Crude drug nearly terete, conical or lecotropal, 5-15 cm long, 2-8 cm in diameter; surface yellow-brown, sometimes with residual cork. Prepared
as transversely cut pieces. The section of rhizome showing narrow cortex and wood, broad pith with altemating yellow-brown and red-brown striae and numerous peculiar vascular bundles in asteriate annular arrangement or scattered; the section of the root showing developed xylem, radially arranged vascular bundles and visible annular marks. Delicately aromatic in odour. Bitter in taste, cold in nature, and attributive to spleen, stomach, large intestine, liver and pericardium channels.
Indication
1. Promote digestion and relieve dyspepsia, purge heat and clear away toxic materials:
(1) for constipation of sthenia-heat type with coma, delirium, convulsion, mania or abdominal distension and pain, usually used together with Natni Sulfas, Fructus Aurantli Immaturus, Cortex Magnoliae Officinalis, (Decoction for Potent Purgation);
(2) for syndrome resulting from evils accumulating in the thorax with abdominal distension and pain, tendemess, dry tongue and thirst, hectic fever, or shortness of breath and restlessness, used together with Radix Euphorbiae Kansui, Natni Sulfas (Decoction for Severe Phlegm-Heat Syndrome in the Chest);
(3) for acute appendicitis, usually used together with Cbrtex Moutan Radicis, Semen Persicae;
(4) for dysentery of dampness-heat type with abdominal pain and tenesmus, used together with Fructus Aurantii Immaturus, Rhizoma Co ptidis, etc;
(5) Single use for biliary infection, cholelithiasis and pancreatitis; for biliary ascariasis used with Herba Artemisiae Scopariae together;
(6) for acute and simple intestinal obstruction, roundworm intestinal obstruction and paralytic intestinal obstruction, Decoction for Potent Purgation may be used;
(7) for food and drug poisoning;
(8) for pulmonary heart disease with respiratory failure and constipation;
(9) for uremia, decoction as enema may be used;
(10) for cold-syndrome with constipation, used together with Radix A coniti Praeparata, Rhizoma Zingiberis, etc.
2. Clear away heat and toxic materials: Oral and external use for furuncle and carbuncle due to intense heat; topical use for bum of medium or small size, cervical erosion and mycotic vaginitis; for furunclosis complicated by septicemia, used together with Flos Lonicerae, Fructus Forsythiae, etc.; also for sorethmat, conjunctival congestion, aphthae and toothache due to domination of fire.
3. Stop bleeding: For peptic ulcer with bleeding, also for hemoptysis and epistaxis due to blood stasis, blood-heat or domination of fire; external use for traumatic bleeding.
4. Promote blood circulation and remove blood stasis: For trauma, especially those of the chest and abdomen with constipation; amenia, dysmenorrhea and postpartum abdominal pain due to blood stasis.
5. Chologogue and relieve jaundice: For preventing and treating icterus neonatorum (including ABO type hemolytic jaundice of newborn), used together with Herba Artemisiae Scopariae, Radix Scutellariae, Radix Glycyrrhizae; for icteric viral jaundice, and acute and serious cases of hepatitis.
Pharmacological Action
1. Sennoside A is the component for purgation.
2. Promoting biliary secretion and enhancing the amount of bilirubin and bile acid.
3. Rhein and Emodin exert bacteriostatic effect by inhibiting the synthesis of DNA, RNA and protein in bacteria.
4. Eniodin is a component for hypotensive.
5. Oral use of its extract reduces the ratio of serum cholesterol and total phospholipid in rabbits with hypercholesterolemia.
6. Chrysophanol, an other active component, exerts a hemostatic effect.
Administration Decoction: 3-12g. Powder: 2-5g, daily dose 4-10g. For purgation, decoct later (only boil for 15 minutes) or soak in the boiled water for oral use.