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.
Viburnum opulus is not official in any country, being deleted from the U. S. P., which formerly included it. It is our native High Cranberry and never was in any extended vogue except in the United States. The berries contain valerianic acid, and the bark carries a trace of it.
Recently the Bureau of Plant Industry, U. S. Department of Agriculture, announced that what has been commonly used as "Cramp Bark" with the botanical name of Viburnum opulus is, in fact, quite a different plant, Acer spicata.
Now Acer spicata is an unknown quantity in medicine, and it does not appear in any pharma copeia or other standard. Wood's Botany lists Acer spicatum, Mountain Maple-bush, and states that it bears a greenish flower. So, then, if we have been actually using a species of maple and not a species of cranberry as "cramp bark," as appears to be the case, it is impossible to give a description here as to the medicinal properties of this plant.
However, the National Formulary IV gives a description of Viburnum opulus, or High Bush Cranberry Bark, and establishes legal standards for it, not, however, using the name "Cramp Bark."
Pilcher reports negative results from viburnum opulus and from valerianic acid on strips of uterine tissue, although valerian had a mild sedative action. The following is taken from his paper in the Jour. Amer. Med. Ass'n., Aug. 12, 1916:
"The active drugs. - The following drugs lessened the amplitude of the excursions or, in the stronger solutions, caused their complete cessation: Unicorn root (Aletris farinosa), Pulsatilla (Pulsatilla pra-tensis), Jamaica dogwood (Ichthyomethia piscipula), and figwort (Scrophularia nodosa); somewhat less active were valerian (Valeriana officinalis) and lady's-slipper (Cypripedium pubescens); the drugs possessing very weak actions were wild yam (Dioscorea villosa), life root (Senecio aureus), and skullcap (Scutellaria lateriflora). The infusions of figwort, Jamaica dogwood and lady's-slipper were active after the manner of the alcoholic preparations, but to a much lesser degree. The infusion of motherwort possessed very insignificant depressant properties, although the fluidextract was inactive. Blue cohosh (Caulophyllum thalictroides), even in the 1:2,000 solution, very promptly put the strips of uterus practically into a state of tonic contraction or tetanus. The action was very persistent and the normal muscular state was not resumed after the strips were placed in fresh Tyrode's solution. The infusion was quite inactive.
"The inactive drugs. - The following were quite inactive or inert, both the fluidextract and the infusion: black haw (Viburnum prunifolium) the bark of both root and stem, cramp bark (Viburnum opulus) [not stated if botanically verified], squaw vine (Mitchella repens), chestnut bark (Castanea dentata), false unicorn (Chamaelirium luteum), passion flower (Passiflora incarnata), blessed thistle (Cnicus bene-dictus), St. Mary's thistle (Silybum marianum or Carduus marianus), and motherwort (Leonurus car-diaca); sodium valerianate was also inactive in solutions up to 1:1,000. The strips were allowed to remain in the solutions of these drugs in concentration up to 1:500 for some time (many of them for an hour) without evidence that the drugs changed the character of the tracings in any way. Control experiments showed that the strips were capable of being depressed or stimulated by these drugs so that there can be no question of their [the drugs] complete inactivity.