Clomethiazole

Last updated
Clomethiazole
Clomethiazole structure.svg
Clomethiazole ball-and-stick model.png
Clinical data
AHFS/Drugs.com International Drug Names
Routes of
administration
Oral
ATC code
Legal status
Legal status
  • BR: Class C1 (Other controlled substances) [1]
  • UK: POM (Prescription only) [2]
  • US: ℞-only
  • In general: ℞ (Prescription only)
Pharmacokinetic data
Elimination half-life 3.6–5 hours
Identifiers
  • 5-(2-Chloroethyl)-4-methyl-1,3-thiazole
CAS Number
PubChem CID
ChemSpider
UNII
KEGG
ChEMBL
CompTox Dashboard (EPA)
ECHA InfoCard 100.007.788 OOjs UI icon edit-ltr-progressive.svg
Chemical and physical data
Formula C6H8ClNS
Molar mass 161.65 g·mol−1
3D model (JSmol)
  • ClCCC1=C(C)N=CS1
  • InChI=1S/C6H8ClNS/c1-5-6(2-3-7)9-4-8-5/h4H,2-3H2,1H3 Yes check.svgY
  • Key:PCLITLDOTJTVDJ-UHFFFAOYSA-N Yes check.svgY
 X mark.svgNYes check.svgY  (what is this?)    (verify)

Clomethiazole (also called chlormethiazole) is a sedative and hypnotic originally developed by Hoffmann-La Roche in the 1930s. [3] The drug is used in treating and preventing symptoms of acute alcohol withdrawal.

Contents

It is structurally related to thiamine (vitamin B1), but acts like a sedative, hypnotic, muscle relaxant and anticonvulsant, having the same mechanism of action as traditional barbiturates. It is also rarely used for the management of agitation, restlessness, short-term insomnia and Parkinson's disease in the elderly, when all other treatment options have failed. In the UK, it is sold under the brand Heminevrin (AstraZeneca Pharmaceuticals). Other brand names include Nevrin in Romania, Distraneurin in Germany and Distraneurine in Spain. The drug is marketed either as a free base in an oily solution containing 192 mg in capsule form, or as clomethiazole edisylate syrup. Due to its high toxicity compared to similar drugs it is not recommended as a first-line treatment for any indication and is particularly dangerous to patients with an elevated risk for drug abuse such as those with a personal or familial history of addiction.

Pharmacology

Clomethiazole acts as a positive allosteric modulator at the barbiturate/picrotoxin site of the GABAA receptor. It works to enhance the action of the neurotransmitter GABA at this receptor. GABA is the major inhibitory neurotransmitter in the brain and produces anxiolytic, anticonvulsant, sedative, and hypnotic effects. Clomethiazole appears to also have another mechanism of action mediating some of its hypothermic and neuroprotective effects. [4] The oxazole homologue is also known [5] providing a little QSAR information.

As opposed to barbiturates, clomethiazole doesn't affect the electrophysiological responses to excitatory aminoacids, and additionally, it also directly acts on chloride ion channels.

Clomethiazole is a potent CYP2E1 enzyme inhibitor which slows down the metabolism of ethanol, hence its use in alcohol withdrawal. It is also an inhibitor of CYP2B6 and possibly CYP2A6 and thus can affect the plasma clearance of substrates of those enzymes.

When clomethiazole is administered via IV in addition to carbamazepine, its clearance is increased by 30%, which results in a proportional reduction in plasma concentration. Therefore, when co-administered with carbamazepine or other potent CYP3A4 inducers via IV, it is necessary to increase the dose of clomethiazole. [6]

Adverse effects

Long term and frequent use of clomethiazole can cause tolerance and physical dependence. Abrupt withdrawal may result in symptoms similar to those of sudden withdrawal of alcohol or benzodiazepines. [7]

Overdose

Clomethiazole is particularly toxic and dangerous if overdosed and is potentially fatal. Alcohol multiplies the effect. As the drug can be fatal in high doses, prescribing clomethiazole outside of a controlled environment, for example a hospital, is not recommended, especially because there are much less toxic alternatives, such as diazepam. Diazepam is one of many drugs belonging to the benzodiazepine class, with a long half-life (50–100 hours) and a very low risk of a fatal overdose, so long as the patient does not also consume alcohol or certain other types of medication. [8]

Due to clomethiazole's action at the barbiturate complex the benzodiazepine antidote flumazenil cannot reverse the effects of overdose; overdose treatment is restricted to the application of a mechanical ventilation apparatus until enough of the drug has been metabolized and/or excreted for the patient to breathe sufficiently without assistance.

Drummer Keith Moon of the rock band The Who died of a clomethiazole overdose. [9]

See also

Related Research Articles

<span class="mw-page-title-main">Benzodiazepine</span> Class of depressant drugs

Benzodiazepines, colloquially called "benzos", are a class of depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed to treat conditions such as anxiety disorders, insomnia, and seizures. The first benzodiazepine, chlordiazepoxide (Librium), was discovered accidentally by Leo Sternbach in 1955 and was made available in 1960 by Hoffmann–La Roche, who soon followed with diazepam (Valium) in 1963. By 1977, benzodiazepines were the most prescribed medications globally; the introduction of selective serotonin reuptake inhibitors (SSRIs), among other factors, decreased rates of prescription, but they remain frequently used worldwide.

<span class="mw-page-title-main">Diazepam</span> Benzodiazepine sedative

Diazepam, first marketed as Valium, is a medicine of the benzodiazepine family that acts as an anxiolytic. It is commonly used to treat a range of conditions, including anxiety, seizures, alcohol withdrawal syndrome, muscle spasms, insomnia, and restless legs syndrome. It may also be used to cause memory loss during certain medical procedures. It can be taken orally, as a suppository inserted into the rectum, intramuscularly, intravenously or used as a nasal spray. When injected intravenously, effects begin in one to five minutes and last up to an hour. Orally, effects begin after 15 to 60 minutes.

<span class="mw-page-title-main">Lorazepam</span> Benzodiazepine medication

Lorazepam, sold under the brand name Ativan among others, is a benzodiazepine medication. It is used to treat anxiety, trouble sleeping, severe agitation, active seizures including status epilepticus, alcohol withdrawal, and chemotherapy-induced nausea and vomiting. It is also used during surgery to interfere with memory formation and to sedate those who are being mechanically ventilated. It is also used, along with other treatments, for acute coronary syndrome due to cocaine use. It can be given orally, transdermal, intravenously (IV), or intramuscularly When given by injection, onset of effects is between one and thirty minutes and effects last for up to a day.

<span class="mw-page-title-main">Sedative</span> Drug that reduces excitement without inducing sleep

A sedative or tranquilliser is a substance that induces sedation by reducing irritability or excitement. They are CNS depressants and interact with brain activity causing its deceleration. Various kinds of sedatives can be distinguished, but the majority of them affect the neurotransmitter gamma-aminobutyric acid (GABA). In spite of the fact that each sedative acts in its own way, most produce relaxing effects by increasing GABA activity.

Colloquially known as "downers", depressants or central depressants are drugs that lower neurotransmission levels, or depress or reduce arousal or stimulation in various areas of the brain. Depressants do not change the mood or mental state of others. Stimulants, or "uppers", increase mental or physical function, hence the opposite drug class from depressants are stimulants, not antidepressants.

<span class="mw-page-title-main">Triazolam</span> Triazolobenzodiazepine class medication

Triazolam, sold under the brand name Halcion among others, is a central nervous system (CNS) depressant tranquilizer of the triazolobenzodiazepine (TBZD) class, which are benzodiazepine (BZD) derivatives. It possesses pharmacological properties similar to those of other benzodiazepines, but it is generally only used as a sedative to treat severe insomnia. In addition to the hypnotic properties, triazolam's amnesic, anxiolytic, sedative, anticonvulsant, and muscle relaxant properties are pronounced as well.

<span class="mw-page-title-main">Clonazepam</span> Benzodiazepine medication

Clonazepam, sold under the brand names Klonopin and Rivotril, is a medication used to prevent and treat anxiety disorders, seizures, bipolar mania, agitation associated with psychosis, OCD and akathisia. It is a long-acting tranquilizer of the benzodiazepine class. It possesses anxiolytic, anticonvulsant, sedative, hypnotic, and skeletal muscle relaxant properties. It is typically taken by mouth but is also used intravenously. Effects begin within one hour and last between eight and twelve hours in adults.

<span class="mw-page-title-main">Flumazenil</span> GABA receptor antagonist drug and benzodiazepine antidote

Flumazenil is a selective GABAA receptor antagonist administered via injection, otic insertion, or intranasally. Therapeutically, it acts as both an antagonist and antidote to benzodiazepines, through competitive inhibition.

<span class="mw-page-title-main">Zopiclone</span> Hypnotic medication

Zopiclone, sold under the brand name Imovane among others, is a nonbenzodiazepine used to treat difficulty sleeping. Zopiclone is molecularly distinct from benzodiazepine drugs and is classed as a cyclopyrrolone. However, zopiclone increases the normal transmission of the neurotransmitter gamma-aminobutyric acid (GABA) in the central nervous system, via modulating GABAA receptors similarly to the way benzodiazepine drugs do.

<span class="mw-page-title-main">Bromazepam</span> Benzodiazepine drug

Bromazepam, sold under many brand names, is a benzodiazepine. It is mainly an anti-anxiety agent with similar side effects to diazepam. In addition to being used to treat anxiety or panic states, bromazepam may be used as a premedicant prior to minor surgery. Bromazepam typically comes in doses of 3 mg and 6 mg tablets.

<span class="mw-page-title-main">Oxazepam</span> Benzodiazepine medication

Oxazepam is a short-to-intermediate-acting benzodiazepine. Oxazepam is used for the treatment of anxiety and insomnia and in the control of symptoms of alcohol withdrawal syndrome.

Physical dependence is a physical condition caused by chronic use of a tolerance-forming drug, in which abrupt or gradual drug withdrawal causes unpleasant physical symptoms. Physical dependence can develop from low-dose therapeutic use of certain medications such as benzodiazepines, opioids, stimulants, antiepileptics and antidepressants, as well as the recreational misuse of drugs such as alcohol, opioids and benzodiazepines. The higher the dose used, the greater the duration of use, and the earlier age use began are predictive of worsened physical dependence and thus more severe withdrawal syndromes. Acute withdrawal syndromes can last days, weeks or months. Protracted withdrawal syndrome, also known as post-acute-withdrawal syndrome or "PAWS", is a low-grade continuation of some of the symptoms of acute withdrawal, typically in a remitting-relapsing pattern, often resulting in relapse and prolonged disability of a degree to preclude the possibility of lawful employment. Protracted withdrawal syndrome can last for months, years, or depending on individual factors, indefinitely. Protracted withdrawal syndrome is noted to be most often caused by benzodiazepines. To dispel the popular misassociation with addiction, physical dependence to medications is sometimes compared to dependence on insulin by persons with diabetes.

<span class="mw-page-title-main">Clorazepate</span> Benzodiazepine medication

Clorazepate, sold under the brand name Tranxene among others, is a benzodiazepine medication. It possesses anxiolytic, anticonvulsant, sedative, hypnotic, and skeletal muscle relaxant properties. Clorazepate is an unusually long-lasting benzodiazepine and serves as a prodrug for the equally long-lasting desmethyldiazepam, which is rapidly produced as an active metabolite. Desmethyldiazepam is responsible for most of the therapeutic effects of clorazepate.

<span class="mw-page-title-main">Loprazolam</span> Benzodiazepine

Loprazolam (triazulenone) marketed under many brand names is a benzodiazepine medication. It possesses anxiolytic, anticonvulsant, hypnotic, sedative and skeletal muscle relaxant properties. It is licensed and marketed for the short-term treatment of moderately-severe insomnia.

<span class="mw-page-title-main">Chlordiazepoxide</span> Benzodiazepine class sedative and hypnotic medication

Chlordiazepoxide, trade name Librium among others, is a sedative and hypnotic medication of the benzodiazepine class; it is used to treat anxiety, insomnia and symptoms of withdrawal from alcohol and other drugs.

<span class="mw-page-title-main">GABA receptor agonist</span> Category of drug

A GABA receptor agonist is a drug that is an agonist for one or more of the GABA receptors, producing typically sedative effects, and may also cause other effects such as anxiolytic, anticonvulsant, and muscle relaxant effects. There are three receptors of the gamma-aminobutyric acid. The two receptors GABA-α and GABA-ρ are ion channels that are permeable to chloride ions which reduces neuronal excitability. The GABA-β receptor belongs to the class of G-Protein coupled receptors that inhibit adenylyl cyclase, therefore leading to decreased cyclic adenosine monophosphate (cAMP). GABA-α and GABA-ρ receptors produce sedative and hypnotic effects and have anti-convulsion properties. GABA-β receptors also produce sedative effects. Furthermore, they lead to changes in gene transcription.

<span class="mw-page-title-main">Benzodiazepine dependence</span> Medical condition

Benzodiazepine dependence defines a situation in which one has developed one or more of either tolerance, withdrawal symptoms, drug seeking behaviors, such as continued use despite harmful effects, and maladaptive pattern of substance use, according to the DSM-IV. In the case of benzodiazepine dependence, the continued use seems to be typically associated with the avoidance of unpleasant withdrawal reaction rather than with the pleasurable effects of the drug. Benzodiazepine dependence develops with long-term use, even at low therapeutic doses, often without the described drug seeking behavior and tolerance.

<span class="mw-page-title-main">Barbiturate</span> Class of depressant drugs derived from barbituric acid

Barbiturates are a class of depressant drugs that are chemically derived from barbituric acid. They are effective when used medically as anxiolytics, hypnotics, and anticonvulsants, but have physical and psychological addiction potential as well as overdose potential among other possible adverse effects. They have been used recreationally for their anti-anxiety and sedative effects, and are thus controlled in most countries due to the risks associated with such use.

<span class="mw-page-title-main">Barbiturate overdose</span> Medical condition

Barbiturate overdose is poisoning due to excessive doses of barbiturates. Symptoms typically include difficulty thinking, poor coordination, decreased level of consciousness, and a decreased effort to breathe. Complications of overdose can include noncardiogenic pulmonary edema. If death occurs this is typically due to a lack of breathing.

Antimanic drugs are psychotropic drugs that are used to treat symptoms of mania. Though there are different causes of mania, the majority is caused by bipolar disorder, therefore antimanic drugs are mostly similar to drugs treating bipolar disorder. Since 1970s, antimanic drugs have been used specifically to control the abnormal elevation of mood or mood swings during manic episodes. One purpose of antimanic drugs is to alleviate or shorten the duration of an acute mania. Another objective is to prevent further cycles of mania and maintain the improvement achieved during the acute episode. The mechanism of antimanic drugs has not yet been fully known, it is proposed that they mostly affect chemical neurotransmitters in the brain. However, the usage of antimanic drugs should be consulted with a doctor or pharmacist due to their side effects and interactions with other drugs and food.

References

  1. Anvisa (2023-03-31). "RDC Nº 784 - Listas de Substâncias Entorpecentes, Psicotrópicas, Precursoras e Outras sob Controle Especial" [Collegiate Board Resolution No. 784 - Lists of Narcotic, Psychotropic, Precursor, and Other Substances under Special Control] (in Brazilian Portuguese). Diário Oficial da União (published 2023-04-04). Archived from the original on 2023-08-03. Retrieved 2023-08-16.
  2. "Heminevrin / Clomethiazole 192 mg Capsules". Electronic Medicines Compendium. Retrieved 7 September 2022.
  3. CHpatent 200248,"Verfahren zur Darstellung von 4-Methyl-5-B-chloräthylthiazol",issued 1938-09-30, assigned to Hoffmann-La Roche
  4. Colado MI, O'Shea E, Esteban B, Granados R, Green AR (February 1999). "In vivo evidence against clomethiazole being neuroprotective against MDMA ('ecstasy')-induced degeneration of rat brain 5-HT nerve terminals by a free radical scavenging mechanism". Neuropharmacology. 38 (2): 307–314. doi:10.1016/S0028-3908(98)00174-9. PMID   10218873. S2CID   14772873.
  5. US Patent 3401172 4-methyl-5-(beta-chloroethyl)oxazole
  6. Distraneurin 192mg: Summary of effects (In Croatian)
  7. Reilly TM (April 1976). "Physiological dependence on, and symptoms of withdrawal from, chlormethiazole". The British Journal of Psychiatry. 128 (4): 375–8. doi:10.1192/bjp.128.4.375. PMID   1260235. S2CID   35647502.
  8. Reith DM, Fountain J, McDowell R, Tilyard M (2003). "Comparison of the fatal toxicity index of zopiclone with benzodiazepines". Journal of Toxicology. Clinical Toxicology. 41 (7): 975–80. doi:10.1081/CLT-120026520. PMID   14705844. S2CID   45870330.
  9. Springer M (2013-05-20). "Keith Moon's Last Interview, 1978" . Retrieved 2014-10-11. An autopsy showed that Moon had taken 32 tablets of clomethiazole. His doctor had told him not to exceed three per day.