Delorazepam
Delorazepam is a benzodiazepine derivative of desmethyldiazepam, primarily used in the treatment of anxiety disorders1 and alcohol withdrawal.2 It is marketed in Italy and is notable for its exceptionally long half-life of 60 to 140 hours.34 Delorazepam also serves as an active metabolite of both diclazepam5 and cloxazolam.6 Like other benzodiazepines, it possesses anxiolytic, muscle relaxant, hypnotic, and anticonvulsant properties,78 and carries a risk of dependence with repeated use.9
Contents
Dosage & Duration
Dosage
Higher doses substantially increase risk of amnestic episodes. Approximately 10 times more potent than diazepam by weight.
Duration
Subjective Effects
The experience is dominated by anxiety relief, sedation, and muscle relaxation, following the classic profile of a long-acting benzodiazepine with hypnotic and anticonvulsant properties. Disinhibition, increased talkativeness, and mild euphoria can accompany the calm, while memory formation becomes unreliable at higher doses. Due to its long duration of action, residual hangover-type drowsiness and impairment can persist well after the main effects subside.
Physical
The body feels heavy, relaxed, and sedated, with skeletal muscle relaxation, dizziness, and unsteady, uncoordinated movement. Respiratory depression becomes a concern at high doses or in combination with other depressants.
Impairment
Sedation
Cognitive
The headspace is calm and disinhibited, with suppressed anxiety, impaired judgement, and pronounced short-term memory impairment. Paradoxical reactions of increased anxiety, excitation, or aggression can occur, particularly in elderly, pediatric, and schizophrenic users, and depressive symptoms may emerge with continued use.
Emotional
Suppressions
Reagent Testing
Loading reagent data
Pharmacology
Pharmacodynamics
Delorazepam acts as a positive allosteric modulator at the GABA-A receptor, binding at the benzodiazepine site.10 This enhances the inhibitory signaling of GABA, producing the anxiolytic, sedative, and muscle relaxant properties characteristic of benzodiazepines.
Pharmacokinetics
Delorazepam is well absorbed after oral administration, reaching peak plasma levels within 1 to 2 hours, with a bioavailability of approximately 77%.3 It undergoes slow hepatic metabolism, producing lorazepam as an active metabolite that represents about 15 to 24 percent of the parent compound.3 The elimination half-life is reported as 80 to 115 hours,4 though one study found an average of 204 hours in healthy patients.11 Significant accumulation occurs with repeated dosing due to this slow metabolism.12 The elderly metabolize delorazepam and its active metabolite more slowly than younger individuals;12 liver disease profoundly extends the half-life, with one report showing values reaching approximately 395 hours.11 Delorazepam is itself an active metabolite of both diclazepam and cloxazolam.
Dangerous
Highest riskThese combinations are considered extremely harmful and should always be avoided. Reactions to these drugs taken in combination are highly unpredictable and have a potential to cause death.
Unsafe
AvoidThere is considerable risk of physical harm when taking these combinations, they should be avoided where possible.
Caution
Use cautionThese combinations are not usually physically harmful, but may produce undesirable effects, such as physical discomfort or overstimulation. Extreme use may cause physical health issues. Synergistic effects may be unpredictable. Care should be taken when choosing to use this combination.
Tolerance
Benzodiazepines, GABAergic depressants (barbiturates, alcohol, GHB/GBL), Z-drugs (zopiclone, zolpidem, zaleplon)
Harm Potential
Addiction & Dependence
Psychological
ModerateDelorazepam is classified as habit-forming with recognized abuse potential.13 Patients with a history of substance or alcohol use are believed to have an increased risk of abuse.14 Non-medical use in prescribed patients has been documented and generally develops slowly, becoming evident only after months or years of therapy.
Physical
Extremely HighPhysical dependence is the most serious effect of long-term use, with withdrawal symptoms that mimic delirium tremens.13 Although withdrawal effects are generally less severe than shorter-acting benzodiazepines, they can be life-threatening.13 Slow tapering over weeks or months is recommended to minimize withdrawal severity. Psychological effects such as rebound anxiety and insomnia may persist for months after physical dependence has been treated.13
Toxicity
Long-term use has been associated with cognitive deficits that may persist longer than six months, with some researchers suggesting these effects could be permanent;15 short-term use carries minimal risk of lasting cognitive impairment.
Psychosis Risk
Paradoxical reactions including increased anxiety, excitation, aggression, and hallucinations may occur but are uncommon. These reactions are more frequent in elderly, pediatric, and schizophrenic patients.16 In rare instances, delorazepam may cause suicidal ideation and actions.9 Contraindicated in patients with severe schizophrenia or schizo-affective disorders.
History & Culture
Delorazepam is an uncommon benzodiazepine that has been marketed primarily in Italy, where it is available under the trade name EN.9 The compound is notable for its relationship to other benzodiazepines in this class, serving as an active metabolite of both…
Legality
References
Source Pages
Citations
- (1989). Double-blind placebo cross-over study of long-acting (chlordesmethyldiazepam) versus short-acting (lorazepam) benzodiazepines in generalized anxiety disorders. International Journal of Clinical Pharmacology Research, 9(3), 203–8. https://pubmed.ncbi.nlm.nih.gov/2568350/1
- (Nov–Dec 1982). [Prevention and therapy of delirium tremens with tiapride and chlordesmethyldiazepam]. Rivista di Neurologia, 52(6), 331–42. https://pubmed.ncbi.nlm.nih.gov/6130594/1
- (1988). Pharmacokinetics and bioavailability of intravenous and oral chlordesmethyldiazepam in humans. European Journal of Clinical Pharmacology, 34(1), 109–12. https://doi.org/10.1007/bf01061430123
- (1986). Pharmacokinetics of chlordesmethyldiazepam after single-dose oral administration in humans. European Journal of Drug Metabolism and Pharmacokinetics, 11(3), 171–4. https://doi.org/10.1007/bf0318984412
- WHO Expert Committee on Drug Dependence. (2020). Critical Review Report: Diclazepam. World Health Organization. https://cdn.who.int/media/docs/default-source/controlled-substances/43rd-ecdd/final-diclazepam-a.pdf12
- (December 2009). Quantification of chlordesmethyldiazepam by liquid chromatography-tandem mass spectrometry: application to a cloxazolam bioequivalence study. Biomedical Chromatography, 23(12), 1266–75. https://doi.org/10.1002/bmc.124912
- (1981). Some behavioral effects of chlorodesmethyldiazepam and lorazepam. Polish Journal of Pharmacology and Pharmacy, 33(6), 597–602. https://pubmed.ncbi.nlm.nih.gov/6127668/1
- (1977). Single-blind evaluation of hypnotic activity of chlordesmethyldiazepam in No-placebo-reactor medical patients. Arzneimittel-Forschung, 27(1), 146–8. https://pubmed.ncbi.nlm.nih.gov/322671/1
- (n.d.). EN (Delorazepam) – Scheda Tecnica e Prescrivibilità. https://www.torrinomedica.it/schede-farmaci/en/123
- (n.d.). Benzodiazepine Dependence: Clinical and Molecular Aspects, Preventive Strategies and Therapeutic Approaches. https://pmc.ncbi.nlm.nih.gov/articles/PMC12898709/1
- (1995). Effects of liver disease on the pharmacokinetics of intravenous and oral chlordesmethyldiazepam. European Journal of Clinical Pharmacology, 48(3–4), 265–8. https://doi.org/10.1007/bf001983091234
- (1986). Age-related multiple-dose pharmacokinetics and anxiolytic effects of delorazepam (chlordesmethyldiazepam). International Journal of Clinical Pharmacology Research, 6(4), 309–14. https://pubmed.ncbi.nlm.nih.gov/2875955/123
- Miller NS, & Gold MS. (2000). Addiction: Part I. Benzodiazepines—Side Effects, Abuse Risk and Alternatives. American Family Physician, 61(7), 2121–2128. https://www.aafp.org/pubs/afp/issues/2000/0401/p2121.html1234
- NICE. (2022). Evidence review: Risk factors for dependence. Medicines associated with dependence or withdrawal symptoms: safe prescribing and withdrawal management for adults. https://www.ncbi.nlm.nih.gov/books/NBK580678/1
- Barker MJ, Greenwood KM, Jackson M, & Crowe SF. (2004). Persistence of cognitive effects after withdrawal from long-term benzodiazepine use: a meta-analysis. Archives of Clinical Neuropsychology, 19(3), 437–454. https://pubmed.ncbi.nlm.nih.gov/15033227/1
- (2014). Paradoxical Reactions from Benzodiazepines – A Review. https://www2.pedsedation.org/sections/newsletters/2014spring/resfellow.html1
Further Reading
Albani et al. Pharmacokinetics of delorazepam after single and repeated oral doses. Eur J Clin Pharmacol 1983;25(1):101-6
Delorazepam - PubChem (NIST)
Delorazepam - Tripsitter Harm Reduction Guide
Italian SPC - EN (delorazepam) 0.5 mg tablets, Chiesi Farmaceutici
PubChem: Compound Summary for CID 4179 (Delorazepam)
Automated synthesisInformation aggregated and synthesized using an autonomous workflow built by Josie Kins.
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