Clomethiazole is a sedative

Sedative

A sedative or tranquilizer is a substance that induces sedation by reducing irritability or excitement....

 and hypnotic

Hypnotic

Hypnotic drugs are a class of psychoactives whose primary function is to induce sleep and to be used in the treatment of insomnia and in surgical anesthesia...

 originally developed by Hoffmann-Le Roche in the 1930s. The drug is used in treating and preventing symptoms of acute alcohol withdrawal.

It is a drug which is structurally related to thiamine

Thiamine

Thiamine or thiamin or vitamin B1 , named as the "thio-vitamine" is a water-soluble vitamin of the B complex. First named aneurin for the detrimental neurological effects if not present in the diet, it was eventually assigned the generic descriptor name vitamin B1. Its phosphate derivatives are...

 (vitamin B₁) but acts like a sedative, hypnotic, muscle relaxant

Muscle relaxant

A muscle relaxant is a drug which affects skeletal muscle function and decreases the muscle tone. It may be used to alleviate symptoms such as muscle spasms, pain, and hyperreflexia. The term "muscle relaxant" is used to refer to two major therapeutic groups: neuromuscular blockers and spasmolytics...

 and 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...

. It is also used for the management of agitation

Psychomotor agitation

Psychomotor agitation is a series of unintentional and purposeless motions that stem from mental tension and anxiety of an individual. This includes pacing around a room, wringing one's hands, pulling off clothing and putting it back on and other similar actions...

, restlessness, short-term insomnia

Insomnia

Insomnia is most often defined by an individual's report of sleeping difficulties. While the term is sometimes used in sleep literature to describe a disorder demonstrated by polysomnographic evidence of disturbed sleep, insomnia is often defined as a positive response to either of two questions:...

 and Parkinson's disease

Parkinson's disease

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

 in the elderly. In the U.K, it is sold under the brand Heminevrin (AstraZeneca Pharmaceuticals). Another brand name includes Nevrin (in Romania). The drug is marketed either as a free base in an oily suspension containing 192 mg in capsule form, or as clomethiazole edisylate (ethane disulfonate) syrup.

Pharmacology

Chlomethiazole acts as a positive allosteric modulator at the barbiturate

Barbiturate

Barbiturates are drugs that act as central nervous system depressants, and can therefore produce a wide spectrum of effects, from mild sedation to total anesthesia. They are also effective as anxiolytics, as hypnotics, and as anticonvulsants...

/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" ....

 site of the GABA-A 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...

. It works to enhance the action of the neurotransmitter

Neurotransmitter

Neurotransmitters are endogenous chemicals that transmit signals from a neuron to a target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to...

 GABA

Gamma-aminobutyric acid

γ-Aminobutyric acid is the chief inhibitory neurotransmitter in the mammalian central nervous system. It plays a role in regulating neuronal excitability throughout the nervous system...

 at this receptor. GABA is the major inhibitory neurotransmitter in the brain and produces anxiolytic, anticonvulsant, sedative, and hypnotic effects. Chlomethiazole appears to also have another mechanism of action mediating some of its hypothermic and neuroprotective effects.

Adverse effects

Long term and frequent use of chlomethiazole can cause tolerance and physical dependence

Physical dependence

Physical dependence refers to a state resulting from chronic use of a drug that has produced tolerance and where negative physical symptoms of withdrawal result from abrupt discontinuation or dosage reduction...

. Abrupt withdrawal may result in symptoms similar to those of sudden withdrawal of alcohol or benzodiazepines.

Overdose

Chlomethiazole is particularly toxic and dangerous in overdose and can be potentially fatal.