Hyoscyamine (also known as daturine or duboisine) is a naturally occurring
tropane alkaloid and plant toxin. It is a
secondary metabolite found in certain plants of the family
Solanaceae, including
henbane,
mandrake,
angel's trumpets,
jimsonweed,
tomato
The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to the Spanish word ...
,
the sorcerers' tree, and
deadly nightshade. It is the
levorotary isomer
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers.
Is ...
of
atropine
Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically given ...
(third of the three major nightshade alkaloids) and thus sometimes known as levo-atropine.
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 of spasms caused by various lower abdominal and bladder disorders including
peptic ulcers,
irritable bowel syndrome,
diverticulitis
Diverticulitis, specifically colonic diverticulitis, is a gastrointestinal disease characterized by inflammation of abnormal pouches— diverticula—which can develop in the wall of the large intestine. Symptoms typically include lower abdomi ...
,
pancreatitis
Pancreatitis is a condition characterized by inflammation of the pancreas. The pancreas is a large organ behind the stomach that produces digestive enzymes and a number of hormones. There are two main types: acute pancreatitis, and chronic p ...
,
colic
Colic or cholic () is a form of pain that starts and stops abruptly. It occurs due to muscular contractions of a hollow tube (small and large intestine, gall bladder, ureter, etc.) in an attempt to relieve an obstruction by forcing content out. ...
, and
interstitial cystitis.
It has also been used to relieve some heart problems, control some of the symptoms of
Parkinson's disease
Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms beco ...
, as well as for control of abnormal respiratory symptoms and "hyper-mucus secretions" in patients with lung disease.
It is also useful in pain control for neuropathic pain, chronic pain and palliative care – "comfort care" – for those with intractable pain from treatment resistant, untreatable, and incurable diseases. When combined with opioids it increases the level of analgesia (pain relief) obtained. Several mechanisms are thought to contribute to this effect. The closely related drugs
atropine
Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically given ...
and
hyoscine
Scopolamine, also known as hyoscine, or Devil's Breath, is a natural or synthetically produced tropane alkaloid and anticholinergic drug that is formally used as a medication for treating motion sickness and postoperative nausea and vomi ...
and other members of the anticholinergic drug group like
cyclobenzaprine
Cyclobenzaprine (sold under the brand name Flexeril, among others) is a medication used for muscle spasms from musculoskeletal conditions of sudden onset. It is not useful in cerebral palsy. It is taken by mouth. Use is not recommended for mor ...
,
trihexyphenidyl
Trihexyphenidyl (THP, benzhexol, trihex, marketed as Artane and others) is an antispasmodic drug used to treat stiffness, tremors, spasms, and poor muscle control. It is an agent of the antimuscarinic class and is often used in management of Pa ...
, and
orphenadrine
Orphenadrine (sold under many brand names) is an anticholinergic drug of the ethanolamine antihistamine class; it is closely related to diphenhydramine. It is a muscle relaxant that is used to treat muscle pain and to help with motor control i ...
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.
Adverse effects
Side effects include dry mouth and throat, increased appetite leading to weight gain, eye pain, blurred vision, restlessness, dizziness,
arrhythmia
Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adult ...
, 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
Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically given ...
but weaker than those of
hyoscine
Scopolamine, also known as hyoscine, or Devil's Breath, is a natural or synthetically produced tropane alkaloid and anticholinergic drug that is formally used as a medication for treating motion sickness and postoperative nausea and vomi ...
, as well as
dicycloverine,
orphenadrine
Orphenadrine (sold under many brand names) is an anticholinergic drug of the ethanolamine antihistamine class; it is closely related to diphenhydramine. It is a muscle relaxant that is used to treat muscle pain and to help with motor control i ...
,
cyclobenzaprine
Cyclobenzaprine (sold under the brand name Flexeril, among others) is a medication used for muscle spasms from musculoskeletal conditions of sudden onset. It is not useful in cerebral palsy. It is taken by mouth. Use is not recommended for mor ...
,
trihexyphenidyl
Trihexyphenidyl (THP, benzhexol, trihex, marketed as Artane and others) is an antispasmodic drug used to treat stiffness, tremors, spasms, and poor muscle control. It is an agent of the antimuscarinic class and is often used in management of Pa ...
, and ethanolamine antihistamines like
phenyltoloxamine
Phenyltoloxamine is an antihistamine with sedative and analgesic effects. It is available in combination with other drugs such as paracetamol (acetominophen).
Common use
Phenyltoloxamine is widely used in preparations as an enhancing agent fo ...
.
Pharmacology
Hyoscyamine is an
antimuscarinic; i.e., an antagonist of
muscarinic acetylcholine receptor
Muscarinic acetylcholine receptors, or mAChRs, are acetylcholine receptors that form G protein-coupled receptor complexes in the cell membranes of certain neurons and other cells. They play several roles, including acting as the main end- ...
s. It blocks the action of
acetylcholine
Acetylcholine (ACh) is an organic chemical that functions in the brain and body of many types of animals (including humans) as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Par ...
at sweat glands (sympathetic) and at
parasympathetic
The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of ...
sites in salivary glands, stomach secretions, heart muscle,
sinoatrial node, smooth muscle in the
gastrointestinal tract
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and ...
, and the
central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...
. It increases cardiac output and heart rate, lowers blood pressure and dries secretions.
It may antagonize
serotonin
Serotonin () or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Its biological function is complex and multifaceted, modulating mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and va ...
.
At comparable doses, hyoscyamine has 98 per cent of the
anticholinergic power of
atropine
Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically given ...
. The other major
belladonna-derived drug
hyoscine
Scopolamine, also known as hyoscine, or Devil's Breath, is a natural or synthetically produced tropane alkaloid and anticholinergic drug that is formally used as a medication for treating motion sickness and postoperative nausea and vomi ...
(known in the United States as Scopolamine) has 92 per cent of the antimuscarinic potency of atropine.
Biosynthesis in plants
Hyoscyamine can be extracted from plants of the family
Solanaceae, notably ''
Datura stramonium''. As hyoscyamine is a direct
precursor
Precursor or Precursors may refer to:
* Precursor (religion), a forerunner, predecessor
** The Precursor, John the Baptist
Science and technology
* Precursor (bird), a hypothesized genus of fossil birds that was composed of fossilized parts of u ...
in the
plant biosynthesis of hyoscine, it is produced via the same
metabolic pathway
In biochemistry, a metabolic pathway is a linked series of chemical reactions occurring within a cell. The reactants, products, and intermediates of an enzymatic reaction are known as metabolites, which are modified by a sequence of chemical ...
.
The
biosynthesis
Biosynthesis is a multi-step, enzyme-catalyzed process where substrates are converted into more complex products in living organisms. In biosynthesis, simple compounds are modified, converted into other compounds, or joined to form macromolecul ...
of hyoscine begins with the
decarboxylation
Decarboxylation is a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO2). Usually, decarboxylation refers to a reaction of carboxylic acids, removing a carbon atom from a carbon chain. The reverse process, which is ...
of ''L''-
ornithine to
putrescine
Putrescine is an organic compound with the formula (CH2)4(NH2)2. It is a colorless solid that melts near room temperature. It is classified as a diamine. Together with cadaverine, it is largely responsible for the foul odor of putrefying flesh ...
by
ornithine decarboxylase
The enzyme ornithine decarboxylase (, ODC) catalyzes the decarboxylation of ornithine (a product of the urea cycle) to form putrescine. This reaction is the committed step in polyamine synthesis. In humans, this protein has 461 amino acids and f ...
EC 4.1.1.17. Putrescine is
methylated to ''N''-methylputrescine by
putrescine ''N''-methyltransferaseEC 2.1.1.53.
A
putrescine oxidase
In enzymology, a putrescine oxidase () is an enzyme that catalyzes the chemical reaction
:putrescine + O2 + H2O \rightleftharpoons 4-aminobutanal + NH3 + H2O2
The 3 substrates of this enzyme are putrescine, O2, and H2O, whereas its 3 produc ...
EC 1.4.3.10 that specifically recognizes methylated putrescine catalyzes the
deamination of this compound to 4-methylaminobutanal which then undergoes a spontaneous ring formation to ''N''-methylpyrrolium cation. In the next step, the pyrrolium cation condenses with
acetoacetic acid yielding
hygrine
Hygrine is a pyrrolidine alkaloid, found mainly in coca leaves (0.2%). It was first isolated by Carl Liebermann in 1889 (along with a related compound cuscohygrine) as an alkaloid accompanying cocaine
Cocaine (from , from , ultimately f ...
. No enzymatic activity could be demonstrated that catalyzes this reaction. Hygrine further rearranges to
tropinone.
Subsequently,
tropinone reductase IEC 1.1.1.206 converts tropinone to
tropine which condenses with
phenylalanine
Phenylalanine (symbol Phe or F) is an essential α-amino acid with the formula . It can be viewed as a benzyl group substituted for the methyl group of alanine, or a phenyl group in place of a terminal hydrogen of alanine. This essential amin ...
-derived phenyllactate to littorine. A
cytochrome P450
Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various co ...
classified as Cyp80F1
oxidizes and rearranges littorine to hyoscyamine
aldehyde
In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl gro ...
.
Bush medicine basis
A
bush medicine
Bush medicine comprises traditional medicines used by Indigenous Australians, being Aboriginal and Torres Strait Islander people. Indigenous people have been using various components of native Australian flora and some fauna as medicine for ...
developed by
Aboriginal peoples of the
eastern states of Australia from the soft
corkwood tree, or ''
Duboisia myoporoides
''Duboisia myoporoides'', or corkwood, is a shrub or tree native to high-rainfall areas on the margins of rainforest in eastern Australia. It has a thick and corky bark.
The leaves are obovate to elliptic in shape, 4–15 cm long and 1–4 ...
'', was used by the
Allies
An alliance is a relationship among people, groups, or states that have joined together for mutual benefit or to achieve some common purpose, whether or not explicit agreement has been worked out among them. Members of an alliance are called ...
in World War II to stop soldiers getting
seasick when they sailed across the
English Channel
The English Channel, "The Sleeve"; nrf, la Maunche, "The Sleeve" ( Cotentinais) or ( Jèrriais), ( Guernésiais), "The Channel"; br, Mor Breizh, "Sea of Brittany"; cy, Môr Udd, "Lord's Sea"; kw, Mor Bretannek, "British Sea"; nl, Het Ka ...
during the
Invasion of Normandy
Operation Overlord was the codename for the Battle of Normandy, the Allied operation that launched the successful invasion of German-occupied Western Europe during World War II. The operation was launched on 6 June 1944 (D-Day) with the Norm ...
. Later, it was found that the same substance could be used in the production of
scopolamine
Scopolamine, also known as hyoscine, or Devil's Breath, is a natural or synthetically produced tropane alkaloid and anticholinergic drug that is formally used as a medication for treating motion sickness and postoperative nausea and vomi ...
and hyoscyamine, which are used in
eye surgery
Eye surgery, also known as ophthalmic or ocular surgery, is surgery performed on the eye or its adnexa, by an ophthalmologist or sometimes, an optometrist. Eye surgery is synonymous with ophthalmology. The eye is a very fragile organ, and requ ...
, and a multi-million dollar industry was built in
Queensland
)
, nickname = Sunshine State
, image_map = Queensland in Australia.svg
, map_caption = Location of Queensland in Australia
, subdivision_type = Country
, subdivision_name = Australia
, established_title = Before federation
, establishe ...
based on this substance.
References
{{Muscarinic acetylcholine receptor modulators
Tropane alkaloids
Muscarinic antagonists
Antispasmodics
Oneirogens
Tropane alkaloids found in Solanaceae
Carboxylate esters
Entheogens
Plant toxins