Hyospaz  

Hyoscyamine

Systematic (IUPAC) name
(8-methyl-8-azabicyclo[3.2.1]oct-3-yl) 3-hydroxy-2-phenyl-propanoate
Identifiers
CAS number	101-31-5
ATC code	A03BA03
PubChem	3661
DrugBank	APRD00607
ChemSpider	10246417
Chemical data
Formula	C17H23NO3
Mol. mass	289.375 g/mol
Pharmacokinetic data
Bioavailability	50% Protein binding
Metabolism	Hepatic
Half life	3-5 hrs.
Excretion	Urine
Therapeutic considerations
Pregnancy cat.	C
Legal status	Prescription only (US)
Routes	Oral, Injection
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Hyoscyamine, pronounced hee-oh-skee-ah-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 (Hyoscyamus niger), mandrake (Mandragora officinarum), jimsonweed (Datura stramonium), and deadly nightshade (Atropa belladonna).

Brand names for hyoscyamine include Symax, HyoMax, Anaspaz, Buwecon, Cystospaz, Levsin, Levbid, Levsinex, Donnamar, NuLev, Spacol T/S, Buscopan (containing the derivative hyoscine-N-butylbromide), Hyospasmol (also hyoscine-N-butylbromide) and Neoquess.

Uses

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. It is may be useful in pain control for neuropathic pain treated with opioids as it increases the level of analgesia obtained. Several mechanisms are thought to contribute to this effect. The closely related drugs atropine and scopolamine and other members of the anticholinergic drug group like cyclobenzaprine, trihexyphenidyl, and orphenadrine are also used for this purpose. When hyoscyamine is used along with opioids or other anti-peristaltic agents, measures to prevent constipation are especially important given the risk of paralytic ileus.

Side effects

Side effects include dry mouth and throat, eye pain, blurred vision, restlessness, dizziness, arrythmia, flushing, and faintness. An overdose will cause headache, nausea, vomiting, and central nervous system symptoms including disorientation, hallucinations, euphoria, sexual arousal, short-term memory loss, and possible coma in extreme cases. Some people can experience transient combativeness. The euphoric and sexual effects are stronger than those of atropine but weaker than those of scopolamine, as well as dicycloverine, orphenadrine, cyclobenzaprine, trihexyphenidyl (street name Sexy Trihexy), ethanolamine antihistamines like phentyltoloxamine and the like

Pharmacology

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.

Isolation

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

References