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Hyoscyamine chemical structure

(8-methyl-8-azabicyclo[3.2.1]oct-3-yl) 3-hydroxy-2-phenyl-propanoate
IUPAC name
CAS number
ATC code


Chemical formula {{{chemical_formula}}}
Molecular weight 289.375 g/mol
Bioavailability 50% Protein binding
Metabolism Hepatic
Elimination half-life 3-5 hrs.
Excretion Urine
Pregnancy category C
Legal status Prescription only (US)
Routes of administration Oral, Injection

Hyoscyamine, pronounced hi-oh-SYE-uh-meen, is a chemical compound, a tropane alkaloid. It is the levorotary isomer to atropine. It is a secondary metabolite found in certain plants of the Solanaceae family, including henbane (Hyoscamus niger), mandrake (Mandragora officinarum), jimsonweed (Datura stramonium), and deadly nightshade (Atropa belladonna).

Brand names for hyoscyamine include Symax, HyoMax, Anaspaz, Buwecon, Cystospaz, Levsin, Levbid, Donnamar, NuLev, Buscopan (containing the derivative hyoscine-N-butylbromide), Hyospasmol (also hyoscine-N-butylbromide) 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 palliative care.

Side effectsEdit

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, sexual arousal, 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 linksEdit


Drug Information Handbook 11th Ed. pp. 710-11. Lexi-Comp

Template:Drugs for functional gastrointestinal disorders

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