Etizolam

Identification

Summary

Etizolam is a thienodiazepine derivative used to treat anxiety and insomnia.

Generic Name
Etizolam
DrugBank Accession Number
DB09166
Background

Etizolam is a thienodiazepine which is chemically related to benzodiazepine (BDZ) drug class; it differs from BDZs in having a benzene ring replaced with a thiophene ring. It is an agonist at GABA-A receptors and possesses amnesic, anxiolytic, anticonvulsant, hypnotic, sedative and skeletal muscle relaxant properties. Initially introduced in 1983 in Japan as treatment for neurological conditions such as anxiety and sleep disorders, etizolam is marketed in Japan, Italy and India. It is not approved for use by FDA in the US; however it remains unscheduled in several states and is legal for research purposes.

Type
Small Molecule
Groups
Experimental
Structure
Thumb
Weight
Average: 342.846
Monoisotopic: 342.070594897
Chemical Formula
C17H15ClN4S
Synonyms
  • 4-(o-Chlorophenyl)-2-ethyl-9-methyl-6H-thieno(3,2-f)-s-triazolo(4,3-a)(1,4)diazepine
  • Etizolam

Pharmacology

Indication

Indicated for the treatment of generalized anxiety disorder with depression, panic disorder and insomnia.

Pharmacology
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Associated Conditions
Contraindications & Blackbox Warnings
Contraindications
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Pharmacodynamics

Etizolam is a CNS depressant with anxiolytic, anticonvulsant, sedative-hypnotic and muscle relaxant effects. It acts on the benzodiazepine site of the GABA-A receptor as an agonist to increase inhibitory GABAergic transmission throughout the central nervous system. Studies indicate that etizolam mediates its pharmacological actions with 6 to 10 times more potency than that of diazepam. Clinical human studies performed in Italy showed clinical effectiveness of etizolam in relieving symptoms in patients with generalized anxiety disorders with depressive symptoms 2,3,4. Etizolam also mediates imipramine-like neuropharmacological and behavioral effects, as well as minor effects on cognitive functioning. It is shown to substitute the actions of a short-acting barbiturate, pentobarbitol, in a drug discrimination study 8. Etizolam is an antagonist at platelet-activating-factor (PAF) receptor and attenuates the recurrence of chronic subdural hematoma after neurosurgery in clinical studies 9. It is shown to inhibit PAF-induced bronchoconstriction and hypotension 5.

Mechanism of action

Etizolam is selectively a full agonist at GABA-A receptors to increase GABAergic transmission and enhance GABA-induced Cl- currents 1. It is reported to bind to the benzodiazepine binding site which is located across the interface between the alpha and gamma subunits. Benzodiazapines are reported to only bind to receptors that contain gamma 2 and alpha 1/2/3/5 subunits 7. Alpha-1-containing receptors mediate the sedative effects of etizolam whereas alpha-2 and alpha-3 subunit-containing receptors mediate the anxiolytic effect 7. Etizolam shows high potency and affinity towards GABA-A receptor with alpha 1 beta 2 gamma 2S subunit combination 1. By binding to the regulatory site of the receptor, etizolam potentiates GABA transmission by facilitating the opening of GABA-induced chloride channels 7. Etizolam is a specific antagonist at PAFR. It inhibits PAF-induced platelet aggregation by inhibiting PAF binding to the receptors located on the surface of platelets with an IC50 of 22nM 5.

TargetActionsOrganism
UPlatelet-activating factor receptor
antagonist
Humans
AGABA(A) Receptor
positive allosteric modulator
Humans
AGABA(A) Receptor Benzodiazepine Binding Site
ligand
Humans
Absorption

Etizolam is well absorbed from the intestines with a biological bioavailability of 93% following oral administration. After a single oral dosing of 0.5mg etizolam, it takes approximately 0.9 hours to reach the peak plasma concentration of 8.3 ng/mL 9.

Volume of distribution

Apparent distribution volume was 0.9 ± 0.2 L/kg following a single oral doing of 0.5mg etizolam 9.

Protein binding

Not Available

Metabolism

Biotransformation of etizolam is extensive and involves hydroxylation and conjugation 9. The main metabolite formed via 1'-hydroxylation is α-hydroxyetizolam which retains pharmacological activity comparable to that of the parent drug, indicating that the action of metabolites may contribute to the clinical effects of etizolam 6. CYP3A4 is predicted to be the main CYP enzyme responsible for mediating etizolam metabolism. CYP2C18 and CYP2C19 are also involved in the metabolic pathways 9,5.

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Route of elimination

In a rat study, the amounts of etizolam excreted was 30% in urine was 70% in feces, while the values in a mouse study were 40% in urine and 60% in feces 9.

Half-life

The average elimination half life of etizolam following a single oral dose of 0.5mg is 3.4 hours but may be increased up to 17 hours depending on the rate of metabolism 9. The main metabolite α-hydroxyetizolam displays a longer elimination half life of 8.2 hours 6.

Clearance

Not Available

Adverse Effects
Adverseeffects
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Toxicity

Major adverse effects include drowsiness, sedation, muscle weakness and incoordination, fainting, headache, confusion, depression, slurred speech, visual disturbances and changes in libido and tremor 8. Flumazenil is a competitive antagonist of GABA-A receptors and can be also used to reverse the effect of etizolam overdosage. Etizolam demonstrates no effects on fertility, development and teratogenicity 9. LD50 values of etizolam when delivered orally, intraperitoneally, and subcutaneously are 3509mg/kg, 825mg/kg, and >5000mg/kg in rats, respectively, and 3070mg/kg, 783mg/kg and 5000mg/kg in mice, respectively MSDS.

Pathways
Not Available
Pharmacogenomic Effects/ADRs
Not Available

Interactions

Drug Interactions
This information should not be interpreted without the help of a healthcare provider. If you believe you are experiencing an interaction, contact a healthcare provider immediately. The absence of an interaction does not necessarily mean no interactions exist.
DrugInteraction
1,2-BenzodiazepineThe risk or severity of adverse effects can be increased when Etizolam is combined with 1,2-Benzodiazepine.
AbametapirThe serum concentration of Etizolam can be increased when it is combined with Abametapir.
AbataceptThe metabolism of Etizolam can be increased when combined with Abatacept.
AbirateroneThe metabolism of Etizolam can be decreased when combined with Abiraterone.
AcenocoumarolThe metabolism of Etizolam can be decreased when combined with Acenocoumarol.
AcetazolamideThe risk or severity of adverse effects can be increased when Acetazolamide is combined with Etizolam.
AcetophenazineThe risk or severity of adverse effects can be increased when Acetophenazine is combined with Etizolam.
AclidiniumEtizolam may increase the central nervous system depressant (CNS depressant) activities of Aclidinium.
AdalimumabThe metabolism of Etizolam can be increased when combined with Adalimumab.
AgomelatineThe risk or severity of adverse effects can be increased when Agomelatine is combined with Etizolam.
Interactions
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Food Interactions
Not Available

Products

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International/Other Brands
Arophalm (Nichi-Iko Pharmaceutical) / Capsafe (Ohara Yakuhin) / Dezolam (Taisho Yakuhin) / E1 (Aarpik) / Eticalm (Towa Yakuhin) / Etisedan (Kyowa Yakuhin) / Etizolan (Kobayashi Kako) / Mozun (Tatsumi Kagaku) / New Zomnia (Molekule) / Nonnerv (Nisshin Pharmaceutical) / Palgin (Fujinaga Seiyaku) / Sylkam (Dr. Reddy's)

Categories

ATC Codes
N05BA19 — Etizolam
Drug Categories
Chemical TaxonomyProvided by Classyfire
Description
This compound belongs to the class of organic compounds known as thienodiazepines. These are heteropolycyclic containing a thiophene ring fused to a diazepine ring. Thiophene is 5-membered ring consisting of four carbon and one sulfur atoms. Diazepine is a 7-membered ring consisting of five carbon and two nitrogen atoms.
Kingdom
Organic compounds
Super Class
Organoheterocyclic compounds
Class
Thienodiazepines
Sub Class
Not Available
Direct Parent
Thienodiazepines
Alternative Parents
2,3,5-trisubstituted thiophenes / Chlorobenzenes / 1,4-diazepines / Aryl chlorides / Triazoles / Heteroaromatic compounds / Ketimines / Propargyl-type 1,3-dipolar organic compounds / Azacyclic compounds / Organopnictogen compounds
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Substituents
1,2,4-triazole / 2,3,5-trisubstituted thiophene / Aromatic heteropolycyclic compound / Aryl chloride / Aryl halide / Azacycle / Azole / Benzenoid / Chlorobenzene / Halobenzene
show 15 more
Molecular Framework
Aromatic heteropolycyclic compounds
External Descriptors
Not Available
Affected organisms
Not Available

Chemical Identifiers

UNII
A76XI0HL37
CAS number
40054-69-1
InChI Key
VMZUTJCNQWMAGF-UHFFFAOYSA-N
InChI
InChI=1S/C17H15ClN4S/c1-3-11-8-13-16(12-6-4-5-7-14(12)18)19-9-15-21-20-10(2)22(15)17(13)23-11/h4-8H,3,9H2,1-2H3
IUPAC Name
7-(2-chlorophenyl)-4-ethyl-13-methyl-3-thia-1,8,11,12-tetraazatricyclo[8.3.0.0²,⁶]trideca-2(6),4,7,10,12-pentaene
SMILES
CCC1=CC2=C(S1)N1C(C)=NN=C1CN=C2C1=CC=CC=C1Cl

References

Synthesis Reference

Tahara T, Araki K, Shiroki M, Matsuo H, Munakata T. Syntheses and structure-activity relationships of 6-aryl-4H-s-triazolo[3,4-c]thieno[2,3-e] [1,4]diazepines. Arzneimittelforschung. 1978;28(7):1153-8.

General References
  1. Sanna E, Pau D, Tuveri F, Massa F, Maciocco E, Acquas C, Floris C, Fontana SN, Maira G, Biggio G: Molecular and neurochemical evaluation of the effects of etizolam on GABAA receptors under normal and stress conditions. Arzneimittelforschung. 1999 Feb;49(2):88-95. [Article]
  2. Casacchia M, Bolino F, Ecari U: Etizolam in the treatment of generalized anxiety disorder: a double-blind study versus placebo. Curr Med Res Opin. 1990;12(4):215-23. [Article]
  3. Bertolino A, Mastucci E, Porro V, Corfiati L, Palermo M, Ecari U, Ceccarelli G: Etizolam in the treatment of generalized anxiety disorder: a controlled clinical trial. J Int Med Res. 1989 Sep-Oct;17(5):455-60. [Article]
  4. Pariante F, Caddeo S, Ecari U: Etizolam in the treatment of generalized anxiety disorder associated with depressive symptoms. Curr Med Res Opin. 1989;11(9):543-9. [Article]
  5. Mikashima H, Takehara S, Muramoto Y, Khomaru T, Terasawa M, Tahara T, Maruyama Y: An antagonistic activity of etizolam on platelet-activating factor (PAF). In vitro effects on platelet aggregation and PAF receptor binding. Jpn J Pharmacol. 1987 Aug;44(4):387-91. [Article]
  6. Fracasso C, Confalonieri S, Garattini S, Caccia S: Single and multiple dose pharmacokinetics of etizolam in healthy subjects. Eur J Clin Pharmacol. 1991;40(2):181-5. [Article]
  7. 43. (2012). In Rang and Dale's Pharmacology (7th ed., pp. 533-538). Edinburgh: Elsevier/Churchill Livingstone. [ISBN:978-0-7020-3471-8]
  8. US Drug Enforcement Administration: ETIZOLAM Drug information [Link]
  9. World Health Organization: Etizolam (INN) Pre-Review Report [Link]
Human Metabolome Database
HMDB0041890
KEGG Drug
D01514
PubChem Compound
3307
PubChem Substance
310265075
ChemSpider
3191
ChEBI
31583
ChEMBL
CHEMBL1289779
ZINC
ZINC000000001402
Wikipedia
Etizolam
MSDS
Download (31.4 KB)

Clinical Trials

Clinical Trials
PhaseStatusPurposeConditionsCount

Pharmacoeconomics

Manufacturers
Not Available
Packagers
Not Available
Dosage Forms
FormRouteStrength
Tablet, film coated
Capsule
Solution / dropsOral
Tablet
Tablet, coated
Prices
Not Available
Patents
Not Available

Properties

State
Solid
Experimental Properties
PropertyValueSource
melting point (°C)147-148World Health Organization: Etizolam (INN) Pre-Review Report
water solubilityPractically insolubleWorld Health Organization: Etizolam (INN) Pre-Review Report
Predicted Properties
PropertyValueSource
Water Solubility0.0425 mg/mLALOGPS
logP2.98ALOGPS
logP2.98ChemAxon
logS-3.9ALOGPS
pKa (Strongest Acidic)18.28ChemAxon
pKa (Strongest Basic)4.64ChemAxon
Physiological Charge0ChemAxon
Hydrogen Acceptor Count3ChemAxon
Hydrogen Donor Count0ChemAxon
Polar Surface Area43.07 Å2ChemAxon
Rotatable Bond Count2ChemAxon
Refractivity104.72 m3·mol-1ChemAxon
Polarizability35.64 Å3ChemAxon
Number of Rings4ChemAxon
Bioavailability1ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleNoChemAxon
MDDR-like RuleNoChemAxon
Predicted ADMET Features
Not Available

Spectra

Mass Spec (NIST)
Not Available
Spectra
SpectrumSpectrum TypeSplash Key
Predicted GC-MS Spectrum - GC-MSPredicted GC-MSNot Available
Predicted MS/MS Spectrum - 10V, Positive (Annotated)Predicted LC-MS/MSNot Available
Predicted MS/MS Spectrum - 20V, Positive (Annotated)Predicted LC-MS/MSNot Available
Predicted MS/MS Spectrum - 40V, Positive (Annotated)Predicted LC-MS/MSNot Available
Predicted MS/MS Spectrum - 10V, Negative (Annotated)Predicted LC-MS/MSNot Available
Predicted MS/MS Spectrum - 20V, Negative (Annotated)Predicted LC-MS/MSNot Available
Predicted MS/MS Spectrum - 40V, Negative (Annotated)Predicted LC-MS/MSNot Available

Targets

Drugtargets2
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Kind
Protein
Organism
Humans
Pharmacological action
Unknown
Actions
Antagonist
General Function
Platelet activating factor receptor activity
Specific Function
Receptor for platelet activating factor, a chemotactic phospholipid mediator that possesses potent inflammatory, smooth-muscle contractile and hypotensive activity. Seems to mediate its action via ...
Gene Name
PTAFR
Uniprot ID
P25105
Uniprot Name
Platelet-activating factor receptor
Molecular Weight
39203.075 Da
References
  1. Mikashima H, Takehara S, Muramoto Y, Khomaru T, Terasawa M, Tahara T, Maruyama Y: An antagonistic activity of etizolam on platelet-activating factor (PAF). In vitro effects on platelet aggregation and PAF receptor binding. Jpn J Pharmacol. 1987 Aug;44(4):387-91. [Article]
Kind
Protein group
Organism
Humans
Pharmacological action
Yes
Actions
Positive allosteric modulator
Curator comments
The GABA(A) receptor is pentameric (i.e. comprising 5 subunit proteins) and therefore has a multitude of potential isoforms. The above target is a collection of all possible GABA(A) subunits that may participate in the formation of the pentameric receptor and is not meant to imply direct a drug-protein interaction for each individual subunit.
General Function
Inhibitory extracellular ligand-gated ion channel activity
Specific Function
Component of the heteropentameric receptor for GABA, the major inhibitory neurotransmitter in the vertebrate brain. Functions also as histamine receptor and mediates cellular responses to histamine...

Components:
References
  1. Sigel E, Steinmann ME: Structure, function, and modulation of GABA(A) receptors. J Biol Chem. 2012 Nov 23;287(48):40224-31. doi: 10.1074/jbc.R112.386664. Epub 2012 Oct 4. [Article]
  2. Zhu S, Noviello CM, Teng J, Walsh RM Jr, Kim JJ, Hibbs RE: Structure of a human synaptic GABAA receptor. Nature. 2018 Jul;559(7712):67-72. doi: 10.1038/s41586-018-0255-3. Epub 2018 Jun 27. [Article]
Kind
Protein group
Organism
Humans
Pharmacological action
Yes
Actions
Ligand
Curator comments
Benzodiazepines modulate GABA(A) function by binding at the interface between alpha (α) and gamma (γ) subunits. Of the 6 α-subunits, only 4 (α-1, -2, -3, and -5) participate in the formation of this binding site. The above target is a collection of all α- and γ-subunits that are known to participate in the formation of the benzodiazepine binding site.
General Function
Inhibitory extracellular ligand-gated ion channel activity
Specific Function
Component of the heteropentameric receptor for GABA, the major inhibitory neurotransmitter in the vertebrate brain. Functions also as histamine receptor and mediates cellular responses to histamine...

Components:
References
  1. Sigel E, Steinmann ME: Structure, function, and modulation of GABA(A) receptors. J Biol Chem. 2012 Nov 23;287(48):40224-31. doi: 10.1074/jbc.R112.386664. Epub 2012 Oct 4. [Article]
  2. Zhu S, Noviello CM, Teng J, Walsh RM Jr, Kim JJ, Hibbs RE: Structure of a human synaptic GABAA receptor. Nature. 2018 Jul;559(7712):67-72. doi: 10.1038/s41586-018-0255-3. Epub 2018 Jun 27. [Article]

Enzymes

Kind
Protein
Organism
Humans
Pharmacological action
Unknown
Actions
Substrate
General Function
Vitamin d3 25-hydroxylase activity
Specific Function
Cytochromes P450 are a group of heme-thiolate monooxygenases. In liver microsomes, this enzyme is involved in an NADPH-dependent electron transport pathway. It performs a variety of oxidation react...
Gene Name
CYP3A4
Uniprot ID
P08684
Uniprot Name
Cytochrome P450 3A4
Molecular Weight
57342.67 Da
References
  1. Araki K, Yasui-Furukori N, Fukasawa T, Aoshima T, Suzuki A, Inoue Y, Tateishi T, Otani K: Inhibition of the metabolism of etizolam by itraconazole in humans: evidence for the involvement of CYP3A4 in etizolam metabolism. Eur J Clin Pharmacol. 2004 Aug;60(6):427-30. Epub 2004 Jul 1. [Article]
  2. World Health Organization: Etizolam (INN) Pre-Review Report [Link]
Kind
Protein
Organism
Humans
Pharmacological action
Unknown
Actions
Substrate
General Function
Steroid hydroxylase activity
Specific Function
Cytochromes P450 are a group of heme-thiolate monooxygenases. In liver microsomes, this enzyme is involved in an NADPH-dependent electron transport pathway. It oxidizes a variety of structurally un...
Gene Name
CYP2C18
Uniprot ID
P33260
Uniprot Name
Cytochrome P450 2C18
Molecular Weight
55710.075 Da
References
  1. World Health Organization: Etizolam (INN) Pre-Review Report [Link]
Kind
Protein
Organism
Humans
Pharmacological action
Unknown
Actions
Substrate
General Function
Steroid hydroxylase activity
Specific Function
Responsible for the metabolism of a number of therapeutic agents such as the anticonvulsant drug S-mephenytoin, omeprazole, proguanil, certain barbiturates, diazepam, propranolol, citalopram and im...
Gene Name
CYP2C19
Uniprot ID
P33261
Uniprot Name
Cytochrome P450 2C19
Molecular Weight
55930.545 Da
References
  1. Fukasawa T, Yasui-Furukori N, Suzuki A, Inoue Y, Tateishi T, Otani K: Pharmacokinetics and pharmacodynamics of etizolam are influenced by polymorphic CYP2C19 activity. Eur J Clin Pharmacol. 2005 Dec;61(11):791-5. Epub 2005 Nov 1. [Article]
  2. Yamamoto T, Furihata K, Hisaka A, Moritoyo T, Ogoe K, Kusayama S, Motohashi K, Mori A, Iwatsubo T, Suzuki H: Notable Drug-Drug Interaction Between Etizolam and Itraconazole in Poor Metabolizers of Cytochrome P450 2C19. J Clin Pharmacol. 2017 Nov;57(11):1491-1499. doi: 10.1002/jcph.956. Epub 2017 Jul 5. [Article]
  3. WHO Critical Review: Etizolam [File]

Drug created on October 13, 2015 23:46 / Updated on May 07, 2021 21:06