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Diclazepam structure.svg
Diclazepam molecule ball.png
Clinical data
Routes of
Oral, sublingual
Legal status
Legal status
  • CA: Schedule IV
  • DE: Anlage II (Authorized trade only, not prescriptible)
  • UK: Class C
  • US: The DEA has announced intent to place Diclazepam under control in Schedule I. [1]
Pharmacokinetic data
Elimination half-life~42 hours[2]
  • 7-Chloro-5-(2-chlorophenyl)-1-methyl-1,3-dihydro-2H-1,4-benzodiazepin-2-one
CAS Number
PubChem CID
CompTox Dashboard (EPA)
Chemical and physical data
Molar mass319.19 g·mol−1
3D model (JSmol)
  • CN1C2=C(C=C(C=C2)Cl)C(C3=C(Cl)C=CC=C3)=NCC1=O
  • InChI=1S/C16H12Cl2N2O/c1-20-14-7-6-10(17)8-12(14)16(19-9-15(20)21)11-4-2-3-5-13(11)18/h2-8H,9H2,1H3
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Diclazepam (Ro5-3448), also known as chlorodiazepam and 2'-chloro-diazepam, is a benzodiazepine and functional analog of diazepam. It was first synthesized by Leo Sternbach and his team at Hoffman-La Roche in 1960.[3] It is not currently approved for use as a medication, but rather sold as an unscheduled substance.[4][5][6][7] Efficacy and safety have not been tested in humans.

In animal models, its effects are similar to diazepam, possessing long-acting anxiolytic, anticonvulsant, hypnotic, sedative, skeletal muscle relaxant, and amnestic properties.[citation needed]


Metabolism of this compound has been assessed,[2] revealing diclazepam has an approximate elimination half-life of 42 hours and undergoes N-demethylation to delorazepam, which can be detected in urine for 6 days following administration of the parent compound.[8] Other metabolites detected were lorazepam and lormetazepam which were detectable in urine for 19 and 11 days, respectively, indicating hydroxylation by cytochrome P450 enzymes occurring concurrently with N-demethylation.

Legal status[edit]

United Kingdom[edit]

In the UK, diclazepam has been classified as a Class C drug by the May 2017 amendment to The Misuse of Drugs Act 1971 along with several other benzodiazepine drugs.[9]

United States[edit]

On the 23rd of December 2022, the Drug Enforcement Administration announced its intent to place Diclazepam into Schedule I.

See also[edit]


  1. ^ "(Proposed Rule) Schedules of Controlled Substances: Temporary Placement of Etizolam, Flualprazolam, Clonazolam, Flubromazolam, and Diclazepam in Schedule I". Drug Enforcement Administration. December 23, 2022.
  2. ^ a b Moosmann B, Bisel P, Auwärter V (July–August 2014). "Characterization of the designer benzodiazepine diclazepam and preliminary data on its metabolism and pharmacokinetics". Drug Testing and Analysis. 6 (7–8): 757–63. doi:10.1002/dta.1628. PMID 24604775.
  3. ^ US 3136815, "Amino substituted benzophenone oximes and derivatives thereof" 
  4. ^ Madeleine Pettersson Bergstrand; Anders Helander; Therese Hansson; Olof Beck (2016). "Detectability of designer benzodiazepines in CEDIA, EMIT II Plus, HEIA, and KIMS II immunochemical screening assays". Drug Testing and Analysis. 9 (4): 640–645. doi:10.1002/dta.2003. PMID 27366870.
  5. ^ Høiseth, Gudrun; Tuv, Silja Skogstad; Karinen, Ritva (2016). "Blood concentrations of new designer benzodiazepines in forensic cases". Forensic Science International. 268: 35–38. doi:10.1016/j.forsciint.2016.09.006. PMID 27685473.
  6. ^ Manchester, Kieran R.; Maskell, Peter D.; Waters, Laura (2018). "Experimental versus theoretical log D7.4, pKa and plasma protein binding values for benzodiazepines appearing as new psychoactive substances". Drug Testing and Analysis. 10 (8): 1258–1269. doi:10.1002/dta.2387. ISSN 1942-7611. PMID 29582576.
  7. ^ Manchester, Kieran R.; Waters, Laura; Haider, Shozeb; Maskell, Peter D. (2022). "The blood-to-plasma ratio and predicted GABAA-binding affinity of designer benzodiazepines". Forensic Toxicology. 40 (2): 349–356. doi:10.1007/s11419-022-00616-y. ISSN 1860-8973. PMC 9715504. PMID 36454409. S2CID 247455284.
  8. ^ Bareggi SR, Truci G, Leva S, Zecca L, Pirola R, Smirne S (1988). "Pharmacokinetics and bioavailability of intravenous and oral chlordesmethyldiazepam in humans". European Journal of Clinical Pharmacology. 34 (1): 109–112. doi:10.1007/bf01061430. PMID 2896126. S2CID 1574555.
  9. ^ "The Misuse of Drugs Act 1971 (Amendment) Order 2017".