Hyoscyamine

Hyoscyamine
Systematic (IUPAC) name
	(8-methyl-8-azabicyclo[3.2.1]oct-3-yl) 3-hydroxy-2-phenylpropanoate
Clinical data
Trade names	Anaspaz, Levbid, Levsin
AHFS/Drugs.com	monograph
MedlinePlus	a684010
Pregnancy cat.	C
Legal status	Prescription only (US)
Routes	Oral, Injection
Pharmacokinetic data
Bioavailability	50% Protein binding
Metabolism	Hepatic
Half-life	3–5 hrs.
Excretion	Urine
Identifiers
CAS number	101-31-5
ATC code	A03BA03
PubChem	CID 154417
DrugBank	DB00424
ChemSpider	10246417
UNII	PX44XO846X
ChEBI	CHEBI:17486
ChEMBL	CHEMBL1697729
Chemical data
Formula	C17H23NO3
Mol. mass	289.375 g/mol
SMILES	eMolecules & PubChem
	InChI InChI=1S/C17H23NO3/c1-18-13-7-8-14(18)10-15(9-13)21-17(20)16(11-19)12-5-3-2-4-6-12/h2-6,13-16,19H,7-11H2,1H3/t13-,14+,15+,16-/m1/s1 ; Key:RKUNBYITZUJHSG-FXUDXRNXSA-N ;
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Hyoscyamine (also known as daturine) is a tropane alkaloid. It is a secondary metabolite found in certain plants of the Solanaceae family, including henbane (Hyoscyamus niger), mandrake (Mandragora officinarum), jimsonweed (Datura stramonium), tomato (Solanum lycopersicum) and deadly nightshade (Atropa belladonna). It is the levorotary isomer of atropine (third of the three major nightshade alkaloids) and thus sometimes known as levo-atropine. Hyoscyamine should not be confused with hyoscine, an older alternate name for the related nightshade-derived anticholinergic scopolamine.

Brand names for hyoscyamine include Symax, HyoMax, Anaspaz, Egazil, Buwecon, Cystospaz, Levsin, Levbid, Levsinex, Donnamar, NuLev, Spacol T/S and Neoquess.

Uses

Hyoscyamine is used to provide symptomatic relief to various gastrointestinal disorders including spasms, peptic ulcers, irritable bowel syndrome, diverticulitis, 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.¹ It 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, arrhythmia, 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. The euphoric and sexual effects are stronger than those of atropine but weaker than those of scopolamine, as well as dicycloverine, orphenadrine, cyclobenzaprine, trihexyphenidyl, and ethanolamine antihistamines like phenyltoloxamine.^{citation needed}

Hallucinogenic use

Hyoscyamine was one of the active principles in many of the "flying ointments" used to obtain flying sensations sought by users of these compounds. Potions, solids of various types, and other forms were used. These ointments could contain any number of ingredients with belladonna, henbane, and other plants of the belladonna and datura families being present almost invariably; they were applied to large areas of the skin with the objective being to see the gods/spirits or to be transported to the Sabbat.

The hallucinations, sensation of flying, often a rapid increase in libido and other characteristic effects of this practice are largely attributable to the CNS and peripheral effects of hyoscyamine and other active drugs present in the ointments such as atropine, scopolamine, and other tropane alkaloids.

The inclusion of belladonna/datura type plants amongst the dozens of ingredients in the Haitian zombie drug is thought by some authorities to be at least somewhat likely, although scopolamine-bearing plant matter is almost certainly not the main active ingredient, which has been theorised to possibly be Tetrodotoxin or a related substance.

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. It also increases cardiac output, dries secretions, and antagonizes serotonin. At comparable doses, hyoscyamine has 98 per cent of the anticholinergic power of atropine. The other major belladonna-derived drug scopolamine has 92 per cent of the antimuscarinic potency of atropine.^{citation needed}

Isolation and plant biosynthesis

Hyoscyamine can be extracted from plants of the Solanaceae family, notably Datura stramonium. As hyoscyamine is a direct precursor in the plant biosynthesis of scopolamine, it is produced via the same metabolic pathway.²

References

^ http://www.nlm.nih.gov/medlineplus/druginfo/meds/a684010.html
^ Ziegler, J; Facchini, PJ (2008). "Alkaloid biosynthesis: metabolism and trafficking.". Annual review of plant biology 59: 735–69. PMID 18251710.

[Hyoscyamine Sulfate]http://www.medscape.com/druginfo/dosage?drugid=6428&drugname=Hyoscyamine+Sulfate+Oral&monotype=default

[0] ttp://www.nlm.nih.gov/medlineplus/druginfo/meds/a684010.html

[1] Ziegler, J; Facchini, PJ (2008). "Alkaloid biosynthesis: metabolism and trafficking.". Annual review of plant biology 59: 735–69. PMID 18251710.

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