This section is from the book "Materia Medica Pharmacy, Pharmacology And Therapeutics", by W. Hale White. Also available from Amazon: Materia Medica Pharmacy, Pharmacology And Therapeutics..
Dose, 1/60 to 1/30 gr.; .001 to .002 gm.
C17 H21No4hbr+3H2O=436.98. The Hydrobromate of an alkaloid obtained from Hyoscyamus.
Colorless, transparent, rhombic crystals, odorless, and having an acrid, slightly bitter taste; permanent in the air.
In 1.9 parts of water, and in 13 parts of Alcohol; very slightly soluble in Ether or Chloroform.
Dose, 1/150 to 1/100 gr.; .0004 to .0006 gm.
That the action of hyoscyamus is almost identical with that of belladonna and stramonium is not surprising when we remember the close resemblance in alkaloidal composition. The following are the chief points of difference: (1) Hyoscyamus contains hyoscine in minute quantities. This is a powerful cerebral and spinal sedative, and therefore the excitation and delirium occasioned by the atropine in belladonna are not so evident when hyoscyamus is given; indeed, that may, owing to the hyoscine in it, distinctly depress the higher functions of the brain. The heart is not quite so powerfully affected by hyoscyamus as by belladonna, for hyoscine has a comparatively feeble cardiac influence. Still it is, of course, affected by the hyoscyamine, which acts like atropine. (2) Hyoscyamus increases the peristaltic contractions of the intestines more powerfully than belladonna, and at the same time it is more efficient in relieving the griping of other purgatives. (3) Hyoscyamus has a more markedly sedative action on the urinary unstriped muscle than belladonna. (4) Hyoscine diminishes intra-ocular tension, therefore hyoscyamus does not affect this so much as belladonna.
Hyoscyamus might be used for the same purpose as belladonna, but is chiefly employed in combination with purgatives to diminish their griping action. It is also largely given to relieve vesical spasm in calculus, cystitis, and prostatitis, usually in conjunction with other urinary sedatives, as buchu, uva ursi, or benzoic acid if the urine is alkaline. It will be noticed that the doses of the preparations of hyoscyamus are larger than those of the corresponding preparations of belladonna.
Hyoscine and hyoscyamine may, if given cautiously, be employed as cerebral depressants, and are used in acute mania, delirium tremens, febrile delirium, and insomnia, sometimes with good results. They are mostly given in asylum practice. Hyoscine is most used, and is usually given subcutaneously. Chorea, paralysis agitans, and other convulsive diseases have been treated with them, but the convulsions always recur when these drugs are discontinued. They must be given very carefully, as the activity of different specimens varies, and fatal results have followed their use. They should never be employed if the patient is weak.