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Systematic (IUPAC) name
9-chloro- 6-(2-chlorophenyl)- 4-hydroxy- 2-methyl- 2,5- diazabicyclo [5.4.0] undeca- 5,8,10,12- tetraen- 3-one
Clinical data
  • D
Routes of
Legal status
Legal status
Pharmacokinetic data
Bioavailability 80%
Metabolism Hepatic
Biological half-life 10–12 hours
Excretion Renal
CAS Number 848-75-9
ATC code N05CD06 (WHO)
PubChem CID 13314
DrugBank ?
Chemical data
Formula C16H12Cl2N2O2
Molar mass 335.2 g/mol[[Script error: No such module "String".]]
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Lormetazepam is available as a generic or available under the following trade or brand names (Noctamid, Ergocalm, Loramet, Dilamet, Sedaben, Stilaze, Nocton, Pronoctan, Noctamide, Loretam, Minias, Aldosomnil) and is also sometimes known as methyllorazepam, is a drug which is a 3-hydroxy[1] benzodiazepine derivative. It possesses hypnotic, anxiolytic, anticonvulsant, sedative and skeletal muscle relaxant properties.

Lormetazepam is not approved for sale in the United States or Canada, though it is licensed in the Netherlands as 1 and 2 mg tablets, under the brand names Loramet and Noctamid, and as generic, available from several different manufacturers. It is licensed in the UK as 0.5 and 1 mg tablets for short term treatment (2–4 weeks) of moderately severe insomnia.

The Dutch, British and French system called the System of Objectified Judgement Analysis for assessing whether drugs should be included in drug formularies based on clinical efficacy, adverse effects, pharmacokinetic properties, toxicity and drug interactions was used to assess lormetazepam. A Dutch analysis using the system found that lormetazepam could be suitable to be included in drug prescribing formularies, although zolpidem, zopiclone and temazepam had higher scores and thus can be seen as relatively favorable.[2]


Lormetazepam is considered a hypnotic benzodiazepine and is indicated for moderately severe insomnia. Lormetazepam is a short-acting benzodiazepine and is sometimes used in patients who have difficulty in maintaining sleep or falling asleep. Hypnotics should only be used on a short-term basis or, in those with chronic insomnia, on an occasional basis.[3]

Side effects

Side effects of lormetazepam are similar to those of other hypnotic benzodiazepines and can for the most part be regarded as a class effect.[4] Whilst lormetazepam has sleep inducing properties it has been found to disrupt normal sleep patterns, such as suppressing REM sleep and has residual effects the next day. Rebound effects have been reported after chronic use including rebound REM.[5] In one clinical trial with patients who had prior experience with older hypnotics temazepam and nitrazepam, most preferred lormetazepam due to less heavy sedation, amnesia, and residual effects.[6] Some side effects, including drowsiness, amnesia, and respiratory depression, are increased when lormetazepam is combined with other drugs with similar effects e.g. alcohol and nonbenzodiazepine drugs. Lormetazepam has been associated with adversely affecting immediate and delayed recall memory functions.[7]

Side effects of lormetazepam include:

Residual 'hangover' effects after nighttime administration of lormetazepam such as sleepiness, impaired psychomotor and cognitive functions may persist into the next day which may impair the ability of users to drive safely and increase risks of falls and hip fractures.[8]

Special precautions

Benzodiazepines require special precaution if used during pregnancy, in children, in alcohol- or drug-dependent individuals and individuals with comorbid psychiatric disorders.[9] Lormetazepam may be unsuitable for the elderly due to residual effects on memory and body sway which may result in falls.[10] Lormetazepam causes impaired driving skills, thus caution is required in individuals who drive or operate machinary.[11]

Tolerance, dependence, and withdrawal

It should be noted that the risks of tolerance, dependence and withdrawal are very low when the drug is used for 2–4 weeks only and that lormetazepam is generally a safe and effective drug when used for no longer than 2–4 weeks. Some sleep disturbance in the form of rebound insomnia can, however, occur even after short-term usage of 7 days.[12] Those with a history of addiction may be at increased risk of problems of tolerance and dependence especially those with a past history of dependency on sedative hypnotic drugs.


Lormetazepam as with other benzodiazepines is generally only recommended for short term use (2–4 weeks) due to tolerance and loss of efficacy. Tolerance to and loss of the sedative effects of benzodiazepine hypnotics occurs within 14 days of regular use.[13]


Dependence is the medical term for addiction. Dependence can either be psychological or physical. Psychological dependence can manifest itself as a reliance on a drug to cope with everyday life or in the form of craving. Physical dependence occurs due to physiological adaptations occurring as the body attempts to overcome the drugs effects which is known as tolerance and the continuing need to take the drug to avoid or suppress withdrawal symptoms which can sometimes resemble the original condition being treated. When the dose or the drug is discontinued withdrawal symptoms typically occur. Lormetazepam as with all other benzodiazepines produces both physical and psychological dependence but the main problem of concern is physical dependence which appears in the form of the benzodiazepine withdrawal syndrome after the dosage is reduced or the drug is stopped completely. The dependence induced by lormetazepam is related to changes in the sensitivity of the GABA-BZD receptor complex.[14]

Withdrawal symptoms

Withdrawal symptoms which can occur from stopping benzodiazepines such as lormetazepam can include:[15]

Abrupt or over rapid withdrawal from high doses can provoke:

Withdrawal symptoms typically subside after 4–8 weeks but in approximately 10-15% of individuals symptoms can persist for many months[16] and in rare cases years.[17] Some "Withdrawal Symptoms" can emerge despite a constant dosage with the body needing extra dosage in order to feel normal. This is sometimes associated with dosage escalation.

Lormetazepam has a short to intermediate half-life of approximately 10–12 hours. Shorter acting benzodiazepine compounds are generally associated with a more intense and immediate withdrawal reaction compared to longer acting benzodiazepines. For this reason it is generally recommended to cross from lormetazepam to an equivalent dose of diazepam to gradually taper the dosage.[18]


The bioavailability of lormetazepam was found to be 80%.[19]

Lormetazepam and other benzodiazepine drugs act as positive modulators at the GABAA benzodiazepine receptor complex. Lormetazepam binds to the benzodiazepine receptor which in turn enhances the effect of the GABAA receptor producing its therapeutic effects as well as adverse effects. When lormetazepam binds to the benzodiazepine receptor sites in sufficient quantities it produces sedation which is used clinically as a therapeutic treatment for insomnia. Lormetazepam alters the brain electrical activity which has been studied via EEG readings.[20] Lormetazepam appears to be more selective in the type of benzodiazepine receptor it binds to showing a higher affinity for the omega 1 receptor which is responsible for sedation.[21] Changes in EEG can therefore be used to measure the sedative sleep promoting properties of lormetazepam.

See also


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External links


fr:Lormétazépam it:Lormetazepam ja:ロルメタゼパム pt:Lormetazepam

  1. The pharmacokinetics of lormetazepam following cimetidine
  2. Lua error in package.lua at line 80: module 'Module:Citation/CS1/Suggestions' not found.
  3. Rickels K. (1986). "The clinical use of hypnotics: indications for use and the need for a variety of hypnotics". Acta Psychiatrica Scandinavica Suppl. 332: 132–41. doi:10.1111/j.1600-0447.1986.tb08990.x. PMID 2883820. 
  4. British National Formulary Benzodiazepines Information
  5. Nicholson, AN; Stone, BM (1982). "Hypnotic activity and effects on performance of lormetazepam and camazepam—analogues of temazepam". Br J Clin Pharmacol. 13 (3): 433–9. PMC 1402107Freely accessible. PMID 6120717. 
  6. Hill RC, Harry TV (1983). "Lormetazepam (Lorámet): a multicentre assessment of its efficacy and acceptability as a hypnotic in out-patients with sleep disturbances". J. Int. Med. Res. 11 (6): 325–32. PMID 6360746. 
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  8. Vermeeren A. (2004). "Residual effects of hypnotics: epidemiology and clinical implications". CNS Drugs. 18 (5): 297–328. doi:10.2165/00023210-200418050-00003. PMID 15089115. 
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  13. Smith AE (1989) Benzodiazepines - Use & Abuse - A GUIDE FOR PRESCRIBERS
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  17. Lader M A pilot study of the effects of flumazenil on symptoms persisting after benzodiazepine withdrawal
  18. (Roche Products (UK) Ltd 1990) Benzodiazepines and Your Patients: A Management Programme
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