AskDefine | Define hyoscyamine

Dictionary Definition

hyoscyamine n : a poisonous crystalline alkaloid (isometric with atropine but more potent); used to treat excess motility of the gastrointestinal tract

User Contributed Dictionary



  1. an alkaloid, the stereoisomer of atropine, used medicinally to treat abdominal pain and similar conditions

Extensive Definition

Hyoscyamine, pronounced hi-oh-SYE-uh-meen, is a chemical compound, a tropane alkaloid it is the levo-isomer to atropine. It is a secondary metabolite found in certain plants of the Solanaceae family, including henbane (Hyoscamus niger) and mandrake (Mandragora officinarum).
Brand names for hyoscyamine include Symax, Anaspaz, Buwecon, Cystospaz, Levsin, Levbid, Donnamar, NuLev, and Neoquess.


Hyoscyamine is used to provide symptomatic relief to various gastrointestinal disorders including spasms, peptic ulcers, irritable bowel syndrome, pancreatitis, colic and cystitis. It has also been used to relieve some heart problems, control some of the symptoms of Parkinson's disease, as well as for control of respiratory secretions in end of life care.

Side effects

Side effects include dry mouth and throat, eye pain, blurred vision, restlessness, dizziness, arrythmia, flushing, faintness. An overdose will cause headache, nausea, vomiting and CNS symptoms including disorientation, hallucinations, euphoria, inappropriate affect, short-term memory loss and possible coma in extreme cases.


Hyoscyamine is an anticholinergic, specifically an antimuscarinic, working by blocking the action of acetylcholine at parasympathetic sites in smooth muscle, secretory glands and the CNS; increases cardiac output, dries secretions, and antagonizes serotonin. At comparable doses, hyoscyamine has 98 per cent of the anticholinergic power of atropine and the other major belladonna-derived drug scopolamine having 92 per cent of the antimuscarinic potency of atropine.


Hyoscyamine can be extracted from plants of the Solanaceae family, notably Datura stramonium. Empirically it is C17H23NO3. Its structural name is α-(hydroxymethyl)-, 8-methyl-8-azabicyclo[3.2.1]oct-3-yl ester, [3(S)-endo]-1αH,5αH-Tropan-3α-ol. Do not crush, chew, or divide the extended-release capsules, otherwise, an overdose will result.

External links


Drug Information Handbook 11th Ed. pp. 710-11. Lexi-Comp
hyoscyamine in German: Hyoscyamin
hyoscyamine in Spanish: Hiosciamina
hyoscyamine in French: Hyoscyamine
hyoscyamine in Dutch: Hyoscyamine
hyoscyamine in Polish: Hioscyjamina
hyoscyamine in Romanian: Hiosciamină
hyoscyamine in Russian: Гиосциамин
hyoscyamine in Swedish: Hyoscyamin
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