Temazepam

7-chloro-3-hydroxy-1-methyl-5-phenyl-3H-1,4-benzodiazepin-2-one

Overview

Temazepam belongs to Depressants / Benzodiazepines.

Key safety note: Temazepam is an intermediate-acting hypnotic benzodiazepine and carries the class's core risks.[2]
Effects
Subjective effects vary. What a substance feels like depends on dose, individual physiology, mindset, and setting. The points below describe commonly reported effects, not guaranteed, uniform, or desirable outcomes.
  • Drowsiness, calm and easier sleep onset and maintenance, coming on within about half an hour.
  • Impaired coordination, concentration and short-term memory (anterograde amnesia), dizziness, and next-morning grogginess.
  • With regular use: tolerance, dependence, and rebound insomnia/anxiety and other withdrawal symptoms on stopping.
Dosing & duration
Harm-reduction note: These are commonly cited reference ranges, not a recommendation or a “safe” dose. Potency, purity, body chemistry, tolerance, and drug combinations vary widely. Start low, go slow, wait for full effects before redosing, and never assume an unknown product matches these figures. Missing data is not evidence of safety.

Oral (hard capsules/tablets and soft-gelatin capsules), prescribed and dose-adjusted by a clinician. Figures are therapeutic (prescribing) context, not a recreational guide.. Temazepam is a prescription hypnotic for short-term use (typically 2–4 weeks including taper). The lowest effective dose is taken shortly before bed, with reduced doses in the elderly and debilitated. It should not be combined with alcohol, opioids or other sedatives, and next-day driving may be impaired.

Dose ranges

Insomnia (adult)

10–20 mg at bedtime (occasionally up to 30 mg)

Elderly / debilitated

7.5–10 mg at bedtime

Duration

onset

≈20–30 min

total

Up to ≈8 h

after effects

Possible next-morning drowsiness. Rebound insomnia on stopping

Chemical & Physical Properties
FormulaC16H13ClN2O2
Molar mass300.74 g/mol
StateSolid (white crystalline powder)
Melting point119–121 °C
Boiling pointNot reported
DensityNot reported
Vapor pressureNot reported
pKaNot reported
LogP2.19
Solubility164 mg/L, 5.34×10⁻² g/L
Refractive indexNot reported
Identifiers & Synonyms
CAS846-50-4
CAS (enantiomer)
PubChem CID5391
InChIKeySEQDDYPDSLOBDC-UHFFFAOYSA-N
InChIInChI=1S/C16H13ClN2O2/c1-19-13-8-7-11(17)9-12(13)14(18-15(20)16(19)21)10-5-3-2-4-6-10/h2-9,15,20H,1H3
SMILESCN1C2=C(C=C(C=C2)Cl)C(=NC(C1=O)O)C3=CC=CC=C3

Synonyms

  • Restoril
  • Normison
  • Euhypnos
  • Jellies
Pharmacodynamics & Biochemistry

Temazepam (Restoril, Normison, Euhypnos) is an intermediate-acting benzodiazepine used chiefly as a hypnotic for insomnia. Like the rest of the class it is a positive allosteric modulator at the benzodiazepine site of the GABA-A receptor (the α/γ2 subunit interface): in the presence of GABA it increases the frequency of chloride-channel opening, enhancing inhibitory neurotransmission to produce sedation, hypnosis, anxiolysis, muscle relaxation and anticonvulsant effects. Structurally it is the 3-hydroxy, N-methyl analogue of oxazepam, and it is itself one of the pharmacologically active metabolites of diazepam. Its metabolism resembles oxazepam's more than that of the long-acting benzodiazepines: temazepam is cleared largely by direct glucuronidation of its 3-hydroxyl group to an inactive O-glucuronide (about 90%), with only minor N-demethylation to oxazepam, and it forms no long-lived active metabolites. This gives it an intermediate elimination half-life of roughly 8–20 hours and a hypnotic duration of up to about 8 hours, long enough to maintain sleep but short enough to limit next-day accumulation, and, like the other conjugated benzodiazepines, it is comparatively well tolerated in the elderly and in hepatic impairment. Oral bioavailability is high (about 96%). Hypnotic effects begin in under 30 minutes and peak plasma levels are reached at roughly 2–3 hours, faster for the soft-gelatin/liquid-filled formulations than for hard capsules. Temazepam has a single chiral centre at C3 and is used as the racemate, as with oxazepam its enantiomers interconvert (racemise) readily in solution, so a single-enantiomer preparation offers no advantage: the existing (R)/(S) depiction is kept without a principal-form badge. Its benzodiazepine-site affinity is high but is not separately curated with a clean quantitative constant in the major binding databases, so it is described here qualitatively rather than with a receptor-binding table.

Biological targets

  • GABA-A

Binding & functional measurements

TargetMeasurementSpecies
GABA-A α1β2γ2 receptorEC50 4.0 nMHuman
Pharmacokinetics
BioavailabilityOral ~96%
Tmax≈2–3 h (faster for soft-gel/liquid-filled capsules)
Half-life≈8–20 h (intermediate)
VdNot reported
Protein bindingNot reported
MetabolismDirect hepatic glucuronidation of the 3-OH to an inactive O-glucuronide (~90%). Minor N-demethylation to oxazepam. No active metabolites
ExcretionRenal (mainly as the glucuronide)
Toxicology & Safety
Harm-reduction note: Toxicity and risk depend on dose, route, purity, combinations, setting, and individual health factors. Missing harms should never be interpreted as evidence of safety.

Not reported

Temazepam is an intermediate-acting hypnotic benzodiazepine and carries the class's core risks. It causes dose-dependent sedation, next-morning drowsiness, dizziness, impaired coordination, concentration and short-term memory (anterograde amnesia), so it impairs driving and increases fall risk, particularly in the elderly. Like all benzodiazepines it produces tolerance, physical dependence and, on stopping after regular use, a withdrawal syndrome (rebound insomnia and anxiety, tremor, sweating and, after high-dose or abrupt cessation, seizures), so courses are kept short (typically 2–4 weeks including a taper). It can cause respiratory depression, which becomes dangerous, and is a leading mechanism of benzodiazepine-related death, when combined with opioids, alcohol or other CNS depressants. Historically, the gel-filled capsules (street names 'jellies', 'eggs') were heated and injected by drug users, causing serious harm including limb ischaemia, gangrene and abscesses. This prompted reformulation and the tighter UK Schedule 3 control. Because it is cleared mainly by direct conjugation rather than oxidation, it has fewer pharmacokinetic drug interactions than most benzodiazepines and is comparatively safer in liver disease and old age. Use cautiously in sleep apnoea, severe respiratory insufficiency, myasthenia gravis, a history of substance misuse, and in pregnancy.[2]

Legal Status
Legal note: Legal status can change over time and may vary by country, region, formulation, analogue status, prescription context, and enforcement practice. Always confirm with current official sources before relying on this section.
Interactions & Contraindications

Drug interactions

Opioids Additive respiratory depression and sedation: a leading cause of benzodiazepine-related death (regulatory boxed warnings).[2]
Alcohol, Benzodiazepines, Gabapentinoids (gabapentin, pregabalin) Additive sedation and respiratory depression, including with barbiturates, sedating antihistamines and sedating antidepressants.[2]

Contraindications

Respiratory disease or sleep apnoea sleep apnoea syndrome, severe respiratory insufficiency or severe hypoventilation.[2]
Myasthenia gravis[2]
Combining with alcohol or other CNS depressants acute alcohol or other CNS-depressant intoxication.[2]
Kidney or liver impairment severe hepatic impairment.[2]
Closed-angle glaucoma acute narrow-angle glaucoma.[2]
History of stimulant or substance use disorder history of substance misuse, with caution in the elderly and in pregnancy or breastfeeding.[2]
Usage & Context
  • A prescription hypnotic for the short-term treatment of severe or debilitating insomnia, taken shortly before bed to shorten sleep latency and improve sleep maintenance.
  • Favoured where a benzodiazepine hypnotic is wanted without the day-after accumulation of long-acting agents, and, like oxazepam and lorazepam, usable in the elderly and in hepatic impairment because its direct-conjugation metabolism produces no active metabolites.
  • Also a pharmacologically active metabolite of diazepam, and misused recreationally (historically including hazardous injection of the gel-capsule formulations).
Sources & Evidence

Further Information