This section is from the book "Botanic Drugs Their Materia Medica, Pharmacology and Therapeutics", by Thomas S. Blair. Also available from Amazon: Botanic Drugs, Their Materia Medica, Pharmacology and Therapeutics.
Culver's Root, Veronica Virginica. Was official in the eighth U. S. P., but has been deleted from the ninth. Not official in any other country. Do not conflict with V. officinalis, or Speedwell, official in Denmark and France, and used as an alterative, tonic, and diuretic.
The recent root of leptandra is a violent cathartic apt to act as an emetic. Leptandrin, its proximate, is a mild cholagogue that appears to influence the muciparous follicles of the intestine. There is some conflict as regards Leptandrin. The product listed by Merck is given in doses of 1 to 8 grains. Pure leptandrin is hard to isolate and is not on the market. I have used leptandrin and found it an uncertain agent. The extract (average dose, 4 grains) and the fl. (average dose, 15 minims) are reliable.
Wonderful claims have, in the past, been made for leptandra; it was even called "vegetable mercury." As a matter of fact, its action does not in the least resemble that of mercury. But 10- to 15-minim doses of a good fl. do serve admirably in atonic states of the liver and bowels, especially when the intestinal glands are inactive. Chronic atonic dyspepsia responds, in many instances, to continuous but moderate dosage. Leptandra is of little value in acute conditions; it is not a very active agent, but it serves well in many cases where a mild cholagogue and laxative is indicated.