A convulsant is a drug which induces convulsion

Convulsion

A convulsion is a medical condition where body muscles contract and relax rapidly and repeatedly, resulting in an uncontrolled shaking of the body. Because a convulsion is often a symptom of an epileptic seizure, the term convulsion is sometimes used as a synonym for seizure...

s and/or epileptic seizures, the opposite of an anticonvulsant

Anticonvulsant

The anticonvulsants are a diverse group of pharmaceuticals used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of bipolar disorder, since many seem to act as mood stabilizers, and in the treatment of neuropathic pain. The goal of an...

. These drugs generally act as stimulant

Stimulant

Stimulants are psychoactive drugs which induce temporary improvements in either mental or physical function or both. Examples of these kinds of effects may include enhanced alertness, wakefulness, and locomotion, among others...

s at low doses, but are not used for this purpose due to the risk of convulsions and consequent excitotoxicity

Excitotoxicity

Excitotoxicity is the pathological process by which nerve cells are damaged and killed by excessive stimulation by neurotransmitters such as glutamate and similar substances. This occurs when receptors for the excitatory neurotransmitter glutamate such as the NMDA receptor and AMPA receptor are...

. Most convulsants are antagonists

Receptor antagonist

A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a receptor, but blocks or dampens agonist-mediated responses...

 (or inverse agonist

Inverse agonist

In the field of pharmacology, an inverse agonist is an agent that binds to the same receptor as an agonist but induces a pharmacological response opposite to that agonist....

s) at either the GABA_A or glycine

Glycine receptor

The glycine receptor, or GlyR, is the receptor for the amino acid neurotransmitter glycine. GlyR is an ionotropic receptor that produces its effects through chloride current...

 receptor

Receptor (biochemistry)

In biochemistry, a receptor is a molecule found on the surface of a cell, which receives specific chemical signals from neighbouring cells or the wider environment within an organism...

s, or ionotropic

Ligand-gated ion channel

Ligand-gated ion channels are one type of ionotropic receptor or channel-linked receptor. They are a group of transmembrane ion channels that are opened or closed in response to the binding of a chemical messenger , such as a neurotransmitter.The binding site of endogenous ligands on LGICs...

 glutamate receptor

Glutamate receptor

Glutamate receptors are synaptic receptors located primarily on the membranes of neuronal cells. Glutamate is one of the 20 amino acids used to assemble proteins and as a result is abundant in many areas of the body, but it also functions as a neurotransmitter and is particularly abundant in the...

 agonist

Agonist

An agonist is a chemical that binds to a receptor of a cell and triggers a response by that cell. Agonists often mimic the action of a naturally occurring substance...

s. Many other drugs may cause convulsions as a side effect at high doses (e.g. bupropion

Bupropion

Bupropion is an atypical antidepressant and smoking cessation aid. The drug is a non-tricyclic antidepressant and differs from most commonly prescribed antidepressants such as SSRIs, as its primary pharmacological action is thought to be norepinephrine-dopamine reuptake inhibition...

, tramadol

Tramadol

Tramadol hydrochloride is a centrally acting synthetic opioid analgesic used in treating moderate pain. The drug has a wide range of applications, including treatment for restless legs syndrome and fibromyalgia...

, pethidine

Pethidine

Pethidine or meperidine Pethidine (INN) or meperidine (USAN) Pethidine (INN) or meperidine (USAN) (commonly referred to as Demerol but also referred to as: isonipecaine; lidol; pethanol; piridosal; Algil; Alodan; Centralgin; Dispadol; Dolantin; Mialgin (in Indonesia); Petidin Dolargan (in Poland);...

, dextropropoxyphene

Dextropropoxyphene

Dextropropoxyphene, manufactured by Eli Lilly and Company, is an analgesic in the opioid category. It is intended to treat mild pain and has, in addition, anti-tussive and local anesthetic effects. It has been taken off the market in Europe and the US due to concerns of fatal overdoses and...

) but only drugs whose primary action is to cause convulsions are known as convulsants.

Uses

Some convulsants such as pentetrazol and flurothyl

Flurothyl

Flurothyl is a volatile liquid drug from the halogenated ether family, related to inhaled anaesthetic agents such as diethyl ether, but having the opposite effects, acting as a stimulant and convulsant...

 were previously used in shock therapy

Shock therapy

Shock therapy or shock treatment may refer to:* A form of aversion therapy in which an electric shock is used as a negative stimulus* Electroconvulsive therapy, or electroshock, a psychiatric treatment in which seizures are electrically induced in anaesthetized patients for therapeutic effect*...

 in psychiatric medicine, as an alternative to electroconvulsive therapy

Electroconvulsive therapy

Electroconvulsive therapy , formerly known as electroshock, is a psychiatric treatment in which seizures are electrically induced in anesthetized patients for therapeutic effect. Its mode of action is unknown...

. Others such as strychnine

Strychnine

Strychnine is a highly toxic , colorless crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents. Strychnine causes muscular convulsions and eventually death through asphyxia or sheer exhaustion...

 and tetramethylenedisulfotetramine

Tetramethylenedisulfotetramine

Tetramethylenedisulfotetramine is an organic compound that is used as a rodenticide . It is an odorless, tasteless white powder that is slightly soluble in water, DMSO and acetone, and insoluble in methanol and ethanol. It is a sulfamide derivative...

 are used as poisons for exterminating pests. Bemegride

Bemegride

Bemegride is a central Nervous System stimulant and antidote for barbiturate poisoning.- John Bodkin Adams case :...

 and flumazenil

Flumazenil

Flumazenil is a benzodiazepine antagonist available for injection only, and the only benzodiazepine receptor antagonist on the market today.It was first introduced in 1987 by Hoffmann-La Roche under the trade name Anexate, but only approved by...

 are used to treat drug overdoses (of barbiturates and benzodiazepine

Benzodiazepine

A benzodiazepine is a psychoactive drug whose core chemical structure is the fusion of a benzene ring and a diazepine ring...

s respectively), but may cause convulsions if the dose is too high. Convulsants are also widely used in scientific research, for instance in the testing of new anticonvulsant drugs. Convulsions are induced in captive animals, then high doses of anticonvulsant drugs are administered.

Examples

GABA_A receptor antagonists, inverse agonists or negative allosteric modulators

• Bemegride
  Bemegride
  Bemegride is a central Nervous System stimulant and antidote for barbiturate poisoning.- John Bodkin Adams case :...
  
  
• Bicuculline
  Bicuculline
  Bicuculline is a light-sensitive competitive antagonist of GABAA receptors. It was originally identified in 1932 in plant alkaloid extracts and has been isolated from Dicentra cucullaria, Adlumia fungosa, Fumariaceae, and several Corydalis species. Since it blocks the inhibitory action of GABA...
  
  
• Cicutoxin
  Cicutoxin
  Cicutoxin is a poisonous polyyne and alcohol found in various plants, most notably water hemlock . It is structurally related to the oenanthotoxin of hemlock water dropwort....
  
  
• Cyclothiazide
  Cyclothiazide
  Cyclothiazide is a benzothiadiazide diuretic and antihypertensive that was originally introduced in the United States in 1963 by Eli Lilly and was subsequently also marketed in Europe and Japan...
  
  
• DMCM
  DMCM
  DMCM is a drug from the beta-carboline family. It acts as an inverse agonist of benzodiazepine receptors, meaning that it causes the opposite effects to the benzodiazepine class of drugs...
  
  
• FG-7142
• Fipronil
  Fipronil
  Fipronil is a broad spectrum insecticide that disrupts the insect central nervous system by blocking the passage of chloride ions through the GABA receptor and glutamate-gated chloride channels, components of the central nervous system. This causes hyperexcitation of contaminated insects' nerves...
  
  
• Flumazenil
  Flumazenil
  Flumazenil is a benzodiazepine antagonist available for injection only, and the only benzodiazepine receptor antagonist on the market today.It was first introduced in 1987 by Hoffmann-La Roche under the trade name Anexate, but only approved by...
  
  
• Flurothyl
  Flurothyl
  Flurothyl is a volatile liquid drug from the halogenated ether family, related to inhaled anaesthetic agents such as diethyl ether, but having the opposite effects, acting as a stimulant and convulsant...
  
  
• Gabazine
  Gabazine
  Gabazine is a drug that acts as an antagonist at GABAA receptors. It is used in scientific research and has no role in medicine, as it would be expected to produce convulsions if used in humans....
  
  
• Oenanthotoxin
  Oenanthotoxin
  Oenanthotoxin is a toxin extracted from hemlock water dropwort and other plants of the genus Oenanthe. It is a central nervous system poison, and acts as a noncompetitive gamma-aminobutyric acid antagonist. This toxin played some role in euthanasia in ancient Sardinia, for inducing risus...
  
  
• Pentetrazol
• Picrotoxin
  Picrotoxin
  Picrotoxin, also known as cocculin, is a poisonous crystalline plant compound, first isolated by Pierre Boullay in 1812. The name "picrotoxin" is a combination of the Greek words "picros" and "toxicon" ....
  
  
• Sarmazenil
  Sarmazenil
  Sarmazenil is a drug from the benzodiazepine family. It acts as a partial inverse agonist of benzodiazepine receptors, meaning that it causes the opposite effects to most benzodiazepine drugs, and instead acts as an anxiogenic and convulsant...
  
  
• Securinine
• Tetramethylenedisulfotetramine
  Tetramethylenedisulfotetramine
  Tetramethylenedisulfotetramine is an organic compound that is used as a rodenticide . It is an odorless, tasteless white powder that is slightly soluble in water, DMSO and acetone, and insoluble in methanol and ethanol. It is a sulfamide derivative...
  
  
• Thujone
  Thujone
  Thujone is a ketone and a monoterpene that occurs naturally in two diastereomeric forms: -α-thujone and -β-thujone. It has a menthol odor. Even though it is best known as a chemical compound in the spirit absinthe, recent tests show absinthe contains only small quantities of thujone, and may or may...
  
  

Glycine receptor antagonists

• Brucine
  Brucine
  Brucine is a bitter alkaloid closely related to strychnine. It occurs in several plant species, the most well known being the Strychnos nux-vomica tree, found in South-East Asia.While brucine is related to strychnine, it is not as poisonous...
  
  
• Colubrine
• Diaboline
• Gelsemine
• Hyenandrine
• Strychnine
  Strychnine
  Strychnine is a highly toxic , colorless crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents. Strychnine causes muscular convulsions and eventually death through asphyxia or sheer exhaustion...
  
  
• Tutin
  Tutin (toxin)
  Tutin is a poisonous plant derivative found in the New Zealand tutu plant . It acts as a potent antagonist of the glycine receptor, and has powerful convulsant effects...
  
  

Ionotropic glutamate receptor agonists

• AMPA
  AMPA
  AMPA is a compound that is a specific agonist for the AMPA receptor, where it mimics the effects of the neurotransmitter glutamate....
  
  
• Domoic acid
  Domoic acid
  Domoic acid , the neurotoxin that causes amnesic shellfish poisoning , also known as zombie acid, is a kainic acid analog, heterocyclic amino acid associated with certain harmful algal blooms.-Occurrence:...
  
  
• Kainic acid
  Kainic acid
  Kainic acid is a natural marine acid present in some seaweed. It is a specific agonist for the kainate receptor used as an ionotropic glutamate receptor which mimics the effect of glutamate...
  
  
• NMDA
  NMDA
  N-Methyl-D-aspartic acid or N-Methyl-D-aspartate is an amino acid derivative which acts as a specific agonist at the NMDA receptor mimicking the action of glutamate, the neurotransmitter which normally acts at that receptor...
  
  
• Quisqualic acid
  Quisqualic acid
  Quisqualic acid is an agonist for both AMPA receptors and group I metabotropic glutamate receptors. It causes excitotoxicity and is used in neuroscience to selectively destroy neurons in the brain or spinal cord...
  
  
• Tetrazolylglycine
  Tetrazolylglycine
  Tetrazolylglycine is a potent and selective NMDA receptor agonist, stimulating the NMDA receptor with higher potency than either glutamate or NMDA. It is a potent convulsant and excitotoxin and is used in scientific research....