Hyoscyamine is a tropane alkaloid

Tropane alkaloid

Tropane alkaloids are a class of alkaloids and secondary metabolites that contain a tropane ring in their chemical structure...

. It is a secondary metabolite

Secondary metabolite

Secondary metabolites are organic compounds that are not directly involved in the normal growth, development, or reproduction of an organism. Unlike primary metabolites, absence of secondary metabolities does not result in immediate death, but rather in long-term impairment of the organism's...

 found in certain plants of the Solanaceae

Solanaceae

Solanaceae are a family of flowering plants that include a number of important agricultural crops as well as many toxic plants. The name of the family comes from the Latin Solanum "the nightshade plant", but the further etymology of that word is unclear...

 family, including henbane

Henbane

Henbane , also known as stinking nightshade or black henbane, is a plant of the family Solanaceae that originated in Eurasia, though it is now globally distributed.-Toxicity and historical usage:...

 (Hyoscyamus niger), mandrake

Mandrake

Mandrake may refer to:* Mandrake , a plant of the genus Mandragora* Mandragora , in occultism* Mandrake Linux, former name of Mandriva Linux, a computer operating system...

  (Mandragora officinarum

Mandragora officinarum

Mandragora officinarum is a species of the plant genus mandrake. It has a variety of medicinal uses, especially anodyne and soporific, though in the past much of the use was due to superstition.-Physical characteristics:...

), jimsonweed (Datura stramonium

Datura stramonium

Datura stramonium, known by the common names Jimson weed, devil's trumpet, devil's weed, thorn apple, tolguacha, Jamestown weed, stinkweed, locoweed, datura, pricklyburr, devil's cucumber, Hell's Bells, moonflower and, in South Africa, malpitte and mad seeds, is a common weed in the...

), tomato

Tomato

The word "tomato" may refer to the plant or the edible, typically red, fruit which it bears. Originating in South America, the tomato was spread around the world following the Spanish colonization of the Americas, and its many varieties are now widely grown, often in greenhouses in cooler...

 (Solanum lycopersicum) and deadly nightshade

Deadly nightshade

Atropa belladonna or Atropa bella-donna, commonly known as Belladonna, Devil's Berries, Death Cherries or Deadly Nightshade, is a perennial herbaceous plant in the family Solanaceae, native to Europe, North Africa, and Western Asia. The foliage and berries are extremely toxic, containing tropane...

 (Atropa belladonna). It is the levorotary isomer

Isomer

In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...

 of atropine

Atropine

Atropine is a naturally occurring tropane alkaloid extracted from deadly nightshade , Jimson weed , mandrake and other plants of the family Solanaceae. It is a secondary metabolite of these plants and serves as a drug with a wide variety of effects...

 (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

Scopolamine

Scopolamine, also known as levo-duboisine, and hyoscine, is a tropane alkaloid drug with muscarinic antagonist effects. It is among the secondary metabolites of plants from Solanaceae family of plants, such as henbane, jimson weed and Angel's Trumpets , and corkwood...

.

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 ulcer

Peptic ulcer

A peptic ulcer, also known as PUD or peptic ulcer disease, is the most common ulcer of an area of the gastrointestinal tract that is usually acidic and thus extremely painful. It is defined as mucosal erosions equal to or greater than 0.5 cm...

s, irritable bowel syndrome

Irritable bowel syndrome

Irritable bowel syndrome is a diagnosis of exclusion. It is a functional bowel disorder characterized by chronic abdominal pain, discomfort, bloating, and alteration of bowel habits in the absence of any detectable organic cause. In some cases, the symptoms are relieved by bowel movements...

, diverticulitis

Diverticulitis

Diverticulitis is a common digestive disease particularly found in the large intestine. Diverticulitis develops from diverticulosis, which involves the formation of pouches on the outside of the colon...

, pancreatitis

Pancreatitis

Pancreatitis is inflammation of the pancreas. It occurs when pancreatic enzymes that digest food are activated in the pancreas instead of the small intestine. It may be acute – beginning suddenly and lasting a few days, or chronic – occurring over many years...

, colic

Colic

Colic is a form of pain which starts and stops abruptly. Types include:*Baby colic, a condition, usually in infants, characterized by incessant crying*Renal colic, a pain in the flank, characteristic of kidney stones...

 and cystitis

Cystitis

Cystitis is a term that refers to urinary bladder inflammation that results from any one of a number of distinct syndromes. It is most commonly caused by a bacterial infection in which case it is referred to as a urinary tract infection.-Signs and symptoms:...

. It has also been used to relieve some heart problems, control some of the symptoms of Parkinson's disease

Parkinson's disease

Parkinson's disease is a degenerative disorder of the central nervous system...

, as well as for control of respiratory secretions in palliative care

Palliative care

Palliative care is a specialized area of healthcare that focuses on relieving and preventing the suffering of patients...

. 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

Atropine

Atropine is a naturally occurring tropane alkaloid extracted from deadly nightshade , Jimson weed , mandrake and other plants of the family Solanaceae. It is a secondary metabolite of these plants and serves as a drug with a wide variety of effects...

 and scopolamine

Scopolamine

Scopolamine, also known as levo-duboisine, and hyoscine, is a tropane alkaloid drug with muscarinic antagonist effects. It is among the secondary metabolites of plants from Solanaceae family of plants, such as henbane, jimson weed and Angel's Trumpets , and corkwood...

 and other members of the anticholinergic drug group like cyclobenzaprine

Cyclobenzaprine

Cyclobenzaprine is a muscle relaxant medication used to relieve skeletal muscle spasms and associated pain in acute musculoskeletal conditions. It is the most well-studied drug for this application, and it also has been used off-label for fibromyalgia treatment.- Mechanism of action :The mechanism...

, trihexyphenidyl

Trihexyphenidyl

Trihexyphenidyl , also known as benzhexol, is an antiparkinsonian agent of the antimuscarinic class. It has been in clinical usage for decades...

, and orphenadrine

Orphenadrine

Orphenadrine is an anticholinergic drug of the ethanolamine antihistamine class with prominent CNS and peripheral actions used to treat painful muscle spasms, other similar conditions, as well as the treatment...

 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

Ileus

Ileus is a disruption of the normal propulsive ability of the gastrointestinal tract.Ileus is commonly defined simply as bowel obstruction. However, authoritative sources define it as decreased motor activity of the GI tract due to non-mechanical causes...

.

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. Some people can experience transient combativeness. The euphoric and sexual effects are stronger than those of atropine

Atropine

Atropine is a naturally occurring tropane alkaloid extracted from deadly nightshade , Jimson weed , mandrake and other plants of the family Solanaceae. It is a secondary metabolite of these plants and serves as a drug with a wide variety of effects...

 but weaker than those of scopolamine

Scopolamine

Scopolamine, also known as levo-duboisine, and hyoscine, is a tropane alkaloid drug with muscarinic antagonist effects. It is among the secondary metabolites of plants from Solanaceae family of plants, such as henbane, jimson weed and Angel's Trumpets , and corkwood...

, as well as dicycloverine, orphenadrine

Orphenadrine

Orphenadrine is an anticholinergic drug of the ethanolamine antihistamine class with prominent CNS and peripheral actions used to treat painful muscle spasms, other similar conditions, as well as the treatment...

, cyclobenzaprine

Cyclobenzaprine

Cyclobenzaprine is a muscle relaxant medication used to relieve skeletal muscle spasms and associated pain in acute musculoskeletal conditions. It is the most well-studied drug for this application, and it also has been used off-label for fibromyalgia treatment.- Mechanism of action :The mechanism...

, trihexyphenidyl

Trihexyphenidyl

Trihexyphenidyl , also known as benzhexol, is an antiparkinsonian agent of the antimuscarinic class. It has been in clinical usage for decades...

, and ethanolamine antihistamines like phenyltoloxamine

Phenyltoloxamine

Phenyltoloxamine is an antihistamine with sedative and analgesic effects. It is a member of the ethanolamine class of antihistaminergic agents and an anticholinergic.-Common use:...

.

Pharmacology

Hyoscyamine is an anticholinergic

Anticholinergic

An anticholinergic agent is a substance that blocks the neurotransmitter acetylcholine in the central and the peripheral nervous system. An example of an anticholinergic is dicycloverine, and the classic example is atropine....

, specifically an antimuscarinic, working by blocking the action of acetylcholine

Acetylcholine

The chemical compound acetylcholine is a neurotransmitter in both the peripheral nervous system and central nervous system in many organisms including humans...

 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

Anticholinergic

An anticholinergic agent is a substance that blocks the neurotransmitter acetylcholine in the central and the peripheral nervous system. An example of an anticholinergic is dicycloverine, and the classic example is atropine....

 power of atropine

Atropine

Atropine is a naturally occurring tropane alkaloid extracted from deadly nightshade , Jimson weed , mandrake and other plants of the family Solanaceae. It is a secondary metabolite of these plants and serves as a drug with a wide variety of effects...

. The other major belladonna-derived drug scopolamine

Scopolamine

Scopolamine, also known as levo-duboisine, and hyoscine, is a tropane alkaloid drug with muscarinic antagonist effects. It is among the secondary metabolites of plants from Solanaceae family of plants, such as henbane, jimson weed and Angel's Trumpets , and corkwood...

 has 92 per cent of the antimuscarinic potency of atropine.

Isolation and plant biosynthesis

Hyoscyamine can be extracted from plants of the Solanaceae

Solanaceae

Solanaceae are a family of flowering plants that include a number of important agricultural crops as well as many toxic plants. The name of the family comes from the Latin Solanum "the nightshade plant", but the further etymology of that word is unclear...

family, notably Datura stramonium

Datura stramonium

Datura stramonium, known by the common names Jimson weed, devil's trumpet, devil's weed, thorn apple, tolguacha, Jamestown weed, stinkweed, locoweed, datura, pricklyburr, devil's cucumber, Hell's Bells, moonflower and, in South Africa, malpitte and mad seeds, is a common weed in the...

. As hyoscyamine is a direct precursor in the plant biosynthesis of scopolamine, it is produced via the same metabolic pathway

Metabolic pathway

In biochemistry, metabolic pathways are series of chemical reactions occurring within a cell. In each pathway, a principal chemical is modified by a series of chemical reactions. Enzymes catalyze these reactions, and often require dietary minerals, vitamins, and other cofactors in order to function...

.