Chlordiazepoxide

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Chlordiazepoxide
Chlordiazepoxide.svg
Chlordiazepoxide3Dan.gif
Systematic (IUPAC) name
7-chloro-2-methylamino-5-phenyl-3H-1,4-benzodiazepine-4-oxide
Clinical data
Trade names Librium
AHFS/Drugs.com monograph
MedlinePlus a682078
Pregnancy cat. D (US)
Legal status Prescription Only (S4) (AU) POM (UK) Schedule IV (US)
Routes oral
intramuscular
Pharmacokinetic data
Metabolism Hepatic
Half-life 5–30 hours (Active metabolite desmethyldiazepam 36-200 hours: other active metabolites include oxazepam.)
Excretion Renal
Identifiers
CAS number 58-25-3 YesY
ATC code N05BA02
PubChem CID 2712
DrugBank DB00475
ChemSpider 10248513 YesY
UNII 6RZ6XEZ3CR YesY
KEGG D00267 YesY
ChEBI CHEBI:3611 YesY
ChEMBL CHEMBL451 YesY
Chemical data
Formula C16H14ClN3O 
Mol. mass 299.75 g/mol
 YesY (what is this?)  (verify)

Chlordiazepoxide[1] /ˌklɔərd.əzɨˈpɒksd/, is a sedative/hypnotic drug and benzodiazepine. It is marketed under the trade names Angirex, Elenium, Klopoxid, Libotryp (also contains Amitriptyline), Librax (also contains clidinium bromide), Libritabs, Librium, Mesural, Multum, Novapam, Risolid, Silibrin, Sonimen and Tropium.

Chlordiazepoxide was the first benzodiazepine to be synthesized and the discovery of chlordiazepoxide was by pure chance.[2] Chlordiazepoxide and other benzodiazepines were initially accepted with widespread public approval but were followed with widespread public disapproval and recommendations for more restrictive medical guidelines for its use.[3]

Chlordiazepoxide has a medium to long half-life but its active metabolite has a very long half-life. The drug has amnestic, anticonvulsant, anxiolytic, hypnotic and skeletal muscle relaxant properties.[4]

History[edit]

Chlordiazepoxide (initially called methaminodiazepoxide) was the first benzodiazepine to be synthesised in the mid-1950s. Chlordiazepoxide was synthesised from work on a chemical dye, quinazolone-3-oxides. It was discovered by accident when in 1957 tests revealed that the compound had hypnotic, anxiolytic and muscle relaxant effects. Three years later chlordiazepoxide was marketed as a therapeutic benzodiazepine medication under the brand name Librium. Following chlordiazepoxide, in 1963 diazepam hit the market under the brand name Valium - and was followed by many further benzodiazepine compounds over the subsequent years and decades.[5]

In 1959 it was used by over 2,000 physicians and more than 20,000 patients. It was described as "chemically and clinically different from any of the tranquilizers, psychic energizers or other psychotherapeutic drugs now available." During studies, chlordiazepoxide induced muscle relaxation and a quieting effect on laboratory animals like mice, rats, cats, and dogs. Fear and aggression were eliminated in much smaller doses than those necessary to produce hypnosis. Chlordiazepoxide is similar to phenobarbital in its anticonvulsant properties. However, it lacks the hypnotic effects of barbiturates. Animal tests were conducted in the Boston Zoo and the San Diego Zoo. Forty-two hospital patients admitted for acute and chronic alcoholism, and various psychoses and neuroses were treated with chlordiazepoxide. In a majority of the patients, anxiety, tension, and motor excitement were "effectively reduced." The most positive results were observed among alcoholic patients. It was reported that ulcers and dermatologic problems, both of which involving emotional factors, were reduced by chlordiazepoxide.[6]

Chlordiazepoxide enabled the treatment of emotional disturbances without a loss of mental acuity or alertness. It assisted persons burdened by compulsive behavior (e.g. feeling compelled to count the slats on venetian blinds upon entering a room).[7] In 1963, approval for use was given to diazepam (Valium), a "simplified" version of chlordiazepoxide, primarily to counteract anxiety symptoms. Sleep-related problems were treated with nitrazepam (Mogadon), which was introduced in 1965, temazepam (Restoril), which was introduced in 1969, and flurazepam (Dalmane), which was introduced in 1973.[8]

Indications[edit]

Chlordiazepoxide is indicated for the short-term (2–4 weeks) treatment of anxiety that is severe and disabling or subjecting the person to unacceptable distress. It is also indicated as a treatment for the management of acute alcohol withdrawal syndrome.[9]

Contraindications[edit]

Use of chlordiazepoxide should be avoided in individuals with the following conditions:

Chlordiazepoxide is generally considered an inappropriate benzodiazepine for the elderly due to its long elimination half-life and the risks of accumulation.[10] Benzodiazepines require special precaution if used in the elderly, pregnancy, children, alcohol- or drug-dependent individuals and individuals with comorbid psychiatric disorders.[11]

Pregnancy[edit]

The research into the safety of benzodiazepines during pregnancy is limited and it is recommended that use of benzodiazepines during pregnancy should be based on whether the benefits outweigh the risks. If chlordiazepoxide is used during pregnancy the risks can be reduced via using the lowest effective dose and for the shortest time possible. Benzodiazepines should generally be avoided during the first trimester of pregnancy. Chlordiazepoxide and diazepam are considered to be among the safer benzodiazepines to use during pregnancy in comparison to other benzodiazepines. Possible adverse effects from benzodiazepine use during pregnancy include, abortion, malformation, intrauterine growth retardation, functional deficits, carcinogenesis and mutagenesis. Caution is also advised during breast feeding as chlordiazepoxide passes into breast milk.[12][13]

Side-effects[edit]

Common side-effects of chlordiazepoxide include:[14]

Chlordiazepoxide in laboratory mice studies impairs latent learning. Benzodiazepines impair learning and memory via their action on benzodiazepine receptors, which causes a dysfunction in the cholinergic neuronal system in mice.[15] It was later found that scopolamine impairment in learning was caused by an increase in benzodiazapine/GABA activity (and that benzodiapines were not associated with the cholinergic system).[16] In tests of various benzodiazepine compounds, chlordiazepoxide was found to cause the most profound reduction in the turnover of 5HT (serotonin) in rats. Serotonin is closely involved in regulating mood and may be one of the causes of feelings of depression in rats using chlordiazepoxide or other benzodiazepines.[17]

Chlordiazepoxide DOJ.jpg

Tolerance and dependence[edit]

Tolerance[edit]

Chronic use of benzodiazepines, such as chlordiazepoxide leads to the development of tolerance with a decrease in number of benzodiazepine binding sites in mouse forebrain.[18] The Committee of Review of Medicines who carried out an extensive review of benzodiazepines including chlordiazepoxide found and were in agreement with the Institute of Medicine (USA) and the conclusions of a study carried out by the White House Office of Drug Policy and the National Institute on Drug Abuse (USA) that there was little evidence that long term use of benzodiazepines were beneficial in the treatment of insomnia due to the development of tolerance. Benzodiazepines tended to lose their sleep promoting properties within 3–14 days of continuous use and in the treatment of anxiety the committee found that there was little convincing evidence that benzodiazepines retained efficacy in the treatment of anxiety after 4 months continuous use due to the development of tolerance.[19]

Dependence[edit]

Chlordiazepoxide can cause physical dependence, addiction and what is known as the benzodiazepine withdrawal syndrome. Withdrawal from chlordiazepoxide or other benzodiazepines often leads to withdrawal symptoms that are similar to those seen with alcohol and barbiturates. The higher the dose and the longer the drug is taken the greater the risk of experiencing unpleasant withdrawal symptoms. Withdrawal symptoms can however occur at standard dosages and also after short term use. Benzodiazepine treatment should be discontinued as soon as possible via a slow and gradual dose reduction regime.[20]

Chlordiazepoxide taken during pregnancy can cause a postnatal benzodiazepine withdrawal syndrome.[21]

Overdose[edit]

An individual who has consumed excess chlordiazepoxide may display some of the following symptoms:

In animal models, the oral median lethal dose of chlordiazepoxide is 537 mg/kg.

Chlordiazepoxide is a drug that is very frequently involved in drug intoxication, including overdose.[22] Chlordiazepoxide overdose is considered a medical emergency and, in general, requires the immediate attention of medical personnel. The antidote for an overdose of chlordiazepoxide (or any other benzodiazepine) is flumazenil (Anexate).

Pharmacology[edit]

Chlordiazepoxide acts on benzodiazepine subreceptors of the main GABAA receptor and this results in an increased binding of the inhibitory neurotransmitter GABA to the GABAA receptor thereby producing inhibitory effects on the central nervous system and body similar to the effects of other benzodiazepines.[23] Chlordiazepoxide is anticonvulsant.[24] There is preferential storage of chlordiazepoxide in some organs including the heart of the neonate. Absorption by any administered route and the risk of accumulation is significantly increased in the neonate. The withdrawal of chlordiazepoxide during pregnancy and breast feeding is recommended, as chlordiazepoxide rapidly crosses the placenta and also is excreted in breast milk.[25] Chlordiazepoxide also decreases prolactin release in rats.[26] Benzodiazepines act via micromolar benzodiazepine binding sites as Ca2+ channel blockers and significantly inhibit depolarization-sensitive Calcium uptake in animal nerve terminal preparations.[27] Chlordiazepoxide inhibits acetylcholine release in mouse hippocampal synaptosomes in vivo. This has been found by measuring sodium-dependent high affinity choline uptake in vitro after pretreatment of the mice in vivo with chlordiazepoxide. This may play a role in chlordiazepoxide's anticonvulsant properties.[28]

Pharmacokinetics[edit]

Chlordiazepoxide is a long acting benzodiazepine drug. The half-life of Chlordiazepoxide is 5 – 30 hours but has an active benzodiazepine metabolite (desmethyldiazepam), which has a half-life of 36 – 200 hours.[29] The half-life of chlordiazepoxide increases significantly in the elderly, which may result in prolonged action as well as accumulation of the drug during repeated administration. Delayed body clearance of the long half-life active metabolite also occurs in those over 60 years of age, which further prolongs the effects of the drugs with additional accumulation after repeated dosing.[30]

Interactions[edit]

Some of the major interactions involving Chlordiazepoxide are listed below.[31]

Recreational use[edit]

Carl F. Essig of the Addiction Research Center of the National Institute of Mental Health spoke at a symposium on drug abuse at an annual meeting of the American Association for the Advancement of Science, in December 1963. He named meprobamate, glutethimide, ethinamate, ethchlorvynol, methyprylon and chlordiazepoxide as drugs whose usefulness can hardly be questioned. However, Essig labeled these newer products as drugs of addiction, like barbiturates, whose habit-forming qualities were more widely known. He mentioned a 90-day study of chlordiazepoxide, which concluded that the automobile accident rate among 68 users was 10 times higher than normal. Participants' daily dosage ranged from 5 to 100 milligrams.[32]

Chlordiazepoxide is a drug of potential misuse and is frequently detected in urine samples of drug users who have not been prescribed the drug.[33] Chlordiazepoxide in animal studies has been shown to increase reward-seeking behaviours, which may suggest an increased risk of addictive behavioural patterns.[34] In addition chlordiazepoxide has been shown to be able to substitute for the behavioural effects of barbiturates in a primate study.[35]

Legal status[edit]

Internationally, chlordiazepoxide is a Schedule IV controlled drug under the Convention on Psychotropic Substances.[36]

Toxicity[edit]

Animal[edit]

Laboratory tests assessing the toxicity of chlordiazepoxide, nitrazepam and diazepam on mice spermatozoa found that chlordiazepoxide produced toxicities in sperm including abnormalities involving both the shape and size of the sperm head. Nitrazepam, however, caused more profound abnormalities than chlordiazepoxide.[37]

Availability[edit]

Chlordiazepoxide is available in 5 mg, 10 mg and 25 mg strengths.

Trade names[edit]

Combination Drugs[edit]

Chemistry[edit]

Chlordiazepoxide is synthesized from 2-amino-5-chlorobenzophenone. This is reacted in the usual manner with hydroxylamine, forming 2-amino-5-chlorobenzophenone oxide, which upon reaction with chloroacetic acid chloride in acetic acid easily cyclizes to 6-chloro-2-chloromethyl-4-phenylquinazolin-3-oxide. Reacting this with a primary amine, methylamine in particular, leads to an interesting rearrangement (with a ring expansion), and the reaction product turns out to be 7-chloro-2-methylamino-5-phenyl-3H-1,4-benzodiazepin-4-oxide. An analogous rearrangement with a ring expansion also proceeds upon reaction with alkaline or alkoxides; however, it should be noted that with dialkylamines, the reaction forms the expected substitution products, 2-dialkylaminomethyl derivatives of 6-chloro- 4-phenylquinazolin-3-oxide. Chlordiazepoxide synthesis.png

  • L.H. Sternbach, U.S. Patent 2,893,992 (1959).
  • G. Muller, J. Warnant, DE 1096363  (1959).
  • Sternbach, L. H.; Reeder, E. (1961). "Quinazolines and 1,4-Benzodiazepines. II.1The Rearrangement of 6-Chloro-2-chloromethyl-4-phenylquinazoline 3-Oxide into 2-Amino Derivatives of 7-Chloro-5-phenyl-3H-1,4-benzodiazepine 4-Oxide". Journal of Organic Chemistry 26 (4): 1111. doi:10.1021/jo01063a034.  edit

See also[edit]

References[edit]

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External links[edit]