Botanical name: 

The leaves and flowering or fruiting tops of Hyoscyamus niger, Linné (Nat. Ord. Solanaceae). Europe; naturalized in waste places in the United States. Dose, 2 to 10 grains.
Common Name: Henbane.

Principal Constituents.—Two alkaloids: Hyoscyamine (C17H23NO3), probably identical with duboisine (from Duboisia) and daturine (from Stramonium); and hyoscine (scopolamine) (C17H21NO4)
Preparation.—Specific Medicine Hyoscyamus. Dose, 1/10 to 20 drops.
Derivative. Hyoscyaminae Hydrobromidum, Hyoscyamine Hydrobromide (Hyoscyamine Bromide). Dose, 1/200 grain.

Specific Indications.—Nervous irritability, with unrest and insomnia; dilated pupils and flushed face, accompanied by debility; fright and restlessness in sleep; night terrors; loquaciousness; garrulousness; destructiveness; busy muttering delirium, or singing, talkativeness, amusing hallucinations and illusions, particularly in fevers; choking sensations; the insomnia of debility, exhaustion, or insanity; the excitability of the insane; urethral irritation in the feeble, with urging to urinate; rapid, palpitating heart action; muscular spasms; spasmodic pain; sharp, dry nervous cough, aggravated by the recumbent position. A remedy to relieve pain, spasm, and nervous unrest in the aged and the infant, and in the anemic and the debilitated.

Action.—The physiological actions of hyoscyamus, belladonna, stramonium, and duboisia are quite similar, differing chiefly in degree and less in quality. They produce the same dryness of the throat, flushing of the face, dilatation of the pupils, quickening of the respiratory and heart action, illusions, hallucinations and delirium. While the alkaloids of these drugs also act in the same general manner, there are shades of difference which make some variation in effects. Thus hyoscine (scopolamine) acts somewhat as a check upon its associated hyoscyamine in the parent drug, the latter alkaloid being more closely allied to atropine in action. This check upon the latter makes hyoscyamus less excitant and less furiously deliriant than its congeners and it is less likely to cause cerebral hyperaemia. Under hyoscyamus the primary stimulation observed under belladonna and stramonium and their alkaloids may be absent, or at least it is of very much shorter duration and subdued character, so that under its influence sleep is induced without much previous excitement. This is of great advantage in the treatment of the insane.

There is little observable difference between atropine and hyoscyamine upon the mechanism of ocular accommodation, but the latter sometimes fails to produce mydriasis. There is also but little variation in their effects upon the heart or breathing. Scopolamine (hyoscine), however, is said to cause stronger mydriasis and more quickly than atropine, though it is of shorter duration. Hyoscyamine is more hypnotic and less deliriant than atropine, but this is probably due to the presence of hyoscine in commercial hyoscyamine. It is well-established knowledge that scopolamine is more depressant to the higher cerebral centers than either hyoscyamine or atropine, and that even smaller amounts act decidedly as a hypnotic. Hyoscyamine acts more powerfully upon the peripheral nerves, hence hyoscyamus is a better agent than belladonna to combine with cathartics to lessen griping and tormina. Moreover, it does not restrain secretion and is likely to prove more or less laxative.

Great care must be observed, however, in the use of hyoscine and hyoscyamine. The former, in particular, in large doses dangerously depresses respiration, and if in any case it must be given in full doses its effects upon breathing should be closely watched.

The symptoms of poisoning by hyoscyamus and its alkaloids are sufficiently similar to those named under belladonna for diagnosis, and the treatment is the same as there recommended.

Therapy.—According to the dose in which it is administered hyoscyamus is a cerebral stimulant or a cerebral sedative. It is largely used under conditions in which opium would be indicated, but is not acceptable on account of the constipation, nausea, and headache induced by it. Hyoscyamus does not, like opium, restrain secretion, and proves laxative rather than constipating. Hyoscyamus is a safer drug for old persons and children than belladonna or opium. As a remedy for pain it is relatively far weaker than the latter, but should be preferred in mild attacks and especially in such when associated with spasmodic tubular contractions.

Hyoscyamus is the remedy for nervous irritability and irritation (small doses), and mental excitation with great motility (large doses).

Hyoscyamus allays spasm and relieves pain. It is a better agent for spasmodic disorders and peripheral pain than belladonna, but less effective than opium. Where it can be made to control the pain, however, it should always be preferred to the latter. Hyoscyamus is a better remedy for spasm, especially tubular and sphincteric spasm, than for pain, but if the latter is caused by the former it is doubly efficient. It cannot be relied upon, however, for very severe paroxysms of either pain or spasm such as attend bad cases of calculi colic—either biliary or renal. But it does very well in the milder attacks. In all painful and spasmodic conditions it takes rather full doses, except in states characterized by nervous irritation with feeble circulation—in other words, in nervous depression rather than in nervous excitability—; then small doses act specifically. Properly selected according to this depression or the contrary, and in doses to meet each condition, it is extremely useful in spasmodic dysmenorrhea, flatulent colic, gastrodynia, spasmodic bowel disorders, painful hemorrhoids, spasmodic cystic pain, spasmodic asthma, and whooping cough. As a remedy for pain it will usually be found to meet depressed conditions best. Hence its value in nervous headache, the headache of debility, the vague pains of so-called chronic rheumatism, idiopathic neuralgia, visceral pain, urethral pain, and that of herpes zoster. The more these cases show nervous irritation, weak circulation, tendency to anemia, and constant but not violent unrest, the better they are helped by small doses of the drug.

Hyoscyamus quiets that form of irritability akin to pain but not amounting to actual pain, such as irritation of the bladder and urethra with tendency to sphincteric spasm. Here nerve force is low and under similar conditions it relieves the ever-annoying urging to urinate accompanied by tenesmus that is so often associated with diurnal as well as nocturnal incontinence of urine, and in the cystic troubles of the aged and women during the menopause. In combination with camphor it has long held a reputation for the relief of nervous erethism produced by the passage of instruments into the urethra.

Cough, whether occurring in acute or chronic disorders, is controlled by hyoscyamus. The more spasmodic or convulsive the better it acts, though for some reason it is not as effective in whooping cough as stramonium, solanum, or belladonna. Probably none of these agents act any too well because there is some causative factor other than spasm, probably of a bacterial character. It relieves the short, dry, explosive cough of bronchitis. It relieves most irritable dry coughs, nervous cough, and harassing bronchial cough, caused or made worse upon lying down. It may be given for long periods, preferably in syrup of wild cherry, to relieve the cough and nervousness and thus promote rest in phthisis. In most of the forms of cough mentioned medium doses must be employed, except where nervous and physical depression is very marked. Hyoscyamus, in the small dose, is often the best agent to use in pneumonia, with dry cough and sub-delirium with widely dilated pupils.

Hyoscyamus is one of the most important agents in nervous and mental diseases. In the small doses it meets the depressive types; in full doses the excitable and furious manias. One of the chief uses of the drug (usually in this instance, hyoscyamine, or preferably hyoscine) is to produce sleep in acute mania. If of the violent, furious and destructive type, with great mental and motor excitability, full doses of hyoscine should be given. But if of the sub-delirious or mildly aberrative form, the smaller doses of hyoscyamus are to be preferred. Often both drugs fail to overcome the insomnia, in which instance wider wakefulness ensues and the patient paces the floor until the effect of the drug is spent. Full doses are usually required in delusional insanity, epileptic mania, recurrent mania, and puerperal mania—all with sleeplessness and great mental excitement. On the contrary when in such disorders as nymphomania following childbirth, and due more to delirium than to passion, and in puerperal mania, in both of which there is a feeble pulse, exhaustion, continuous but mild mental agitation, and nervous unrest, then small doses of the parent drug give the best results. Small doses of hyoscyamus are also to be preferred in the insanities, and in the delirium of acute diseases, when the patient indulges in singing, continuous talking, or low muttering delirium, or when garrulous and quarrelsome, but not violent.

When insomnia depends upon mere excitability, or when it is needed to relieve restlessness and unpleasant dreams during sleep, small doses of hyoscyamus are splendidly effective. These conditions often occur during the acute diseases of children and are promptly met by the drug. For the wandering delirium of exhaustion—the typhomania of typhoid fever, it is often the best calmative we can employ. The patient feels that he is away from home and friends and constantly asks and makes an effort "to go home". In hysteria with frequent voiding of small quantities of urine hyoscyamus should be given in fractional doses.

If it is borne in mind that all of the solanaceae in true therapeutic doses produce effects opposite from those of their gross physiologic action, it will not be difficult to apply them specifically. If strong sedation is needed, the large doses are to be given; if stimulation, the small doses. For violent maniacal excitement the alkaloids are preferable: for mild forms, hyoscyamus.

Hyoscine is sometimes used in attempts to cure the opium habit. For the violent excitement following the complete withdrawal of the drug it is useful, but it should not be given continuously. It should be regarded here as an emergency remedy and so employed. It is an easy matter to permanently damage the intellect with the powerful solanaceous alkaloids.

The Eclectic Materia Medica, Pharmacology and Therapeutics, 1922, was written by Harvey Wickes Felter, M.D.