Systematic (IUPAC) name
Clinical data
Pregnancy cat.
  • X
Legal status
Routes Oral
Pharmacokinetic data
Bioavailability 95%
Metabolism Hepatic
Half-life 14-30 hours
Excretion Renal
CAS number  N
ATC code N05
ChemSpider  YesY
Chemical data
Formula C16H13N3O3 
Mol. mass 295.3

Nimetazepam (marketed under brand name Erimin) is an intermediate-acting hypnotic drug which is a benzodiazepine derivative. It was first synthesized by a team at Hoffmann-La Roche in 1962.[1] It possesses hypnotic, anxiolytic, sedative, and skeletal muscle relaxant properties. Nimetazepam is also an anticonvulsant.[2] It is sold in 5 mg tablets known as Erimin. It is generally prescribed for the short-term treatment of severe insomnia in patients who have difficulty falling asleep or maintaining sleep.


Taken orally, nimetazepam has very good bioavailability with nearly 100% being absorbed from the gut. It is among the most rapidly absorbed and quickest acting oral benzodiazepines, and hypnotic effects are typically felt within 15–30 minutes after oral ingestion. The blood level decline of the parent drug was biphasic with the short half-life ranging from 0.5-0.7 hours and the terminal half-life from 8–26.5 hours (mean 17.25 hours). It is the N-methylated analogue of nitrazepam (Mogadon, Alodorm), to which it is partially metabolised. Nitrazepam has a long elimination half-life, so effects of repeated dosage tend to be cumulative.

Recreational use

Nimetazepam has a reputation in Malaysia for being particularly subject to abuse especially by persons addicted to amphetamines or opiates.[3][4]

Legal status

Nimetazepam is currently a Schedule IV drug under the international Convention on Psychotropic Substances of 1971.[5]

In Singapore, nimetazepam is a class C drug under the Misuse of Drugs Act.[6]

In Hong Kong, nimetazepam is regulated under Schedule 1 of Hong Kong's Chapter 134 Dangerous Drugs Ordinance. Nimetazepam can only be used legally by health professionals and for university research purposes. The substance can be given by pharmacists under a prescription. Anyone who supplies the substance without prescription can be fined $10000 (HKD). The penalty for trafficking or manufacturing the substance is a $5,000,000 (HKD) fine and life imprisonment. Possession of the substance for consumption without license from the Department of Health is illegal with a $1,000,000 (HKD) fine and/or 7 years of jail time.[7]

In Victoria Australia, nimetazepam is regulated under Schedule 11 of "Drugs, Poisons and Controlled substances act 1981". It is deemed to fall under the category of "7-NITRO-1,4-BENZODIAZEPINES not included elsewhere in this Part". .[8]


In a rat study Nimetazepam showed greater damage to the fetus, as did nitrazepam when compared against other benzodiazepines, all at a dosage of 100 mg/kg. Diazepam however showed relatively weak fetal toxicities.[9] The same fetotoxicity of nitrazepam could not be observed in mice and is likely due to the particular metabolism of the drug in the rat.[10]

See also


  1. ^ US patent 3109843, Reeder, E. ; Sternbach, L. H., "Process for preparing 5-phenyl-1,2-dihydro-3H-1,4-benzodiazepines", issued 1963-11-05, assigned to Hoffmann-La Roche 
  2. ^ Fukinaga, M.; Ishizawa, K.; Kamei, C. (1998). "Anticonvulsant properties of 1,4-benzodiazepine derivatives in amygdaloid-kindled seizures and their chemical structure-related anticonvulsant action". Pharmacology 57 (5): 233–241.  
  3. ^ Chong, Y. K.; Kaprawi, M. M.; Chan, K. B. (2004). "The Quantitation of Nimetazepam in Erimin-5 Tablets and Powders by Reverse-Phase HPLC". Microgram Journal 2 (1–4): 27–33. 
  4. ^ Devaney, M.; Reid, G.; Baldwin, S. (2005). "Situational analysis of illicit drug issues and responses in the Asia-Pacific region" (pdf). ANCD Research Paper 12. Canberra: Australian National Council on Drugs. 
  5. ^ "List of psychotropic substances under international control" (pdf). Green List Annex to the annual statistical report on psychotropic substances (form P) (23rd ed.). International Narcotics Control Board. August 2003. Retrieved 2011-12-06. 
  6. ^ "Misuse of drugs act, chapter 185". 
  7. ^ "Bilingual Laws Information System". The Government of the Hong Kong Special Administrative Region of the People's Republic of China. 
  8. ^ "Victorian Legislation and Parliamentary Documents". The State Government Victoria. 
  9. ^ Saito, H.; Kobayashi, H.; Takeno, S.; Sakai, T. (1984). "Fetal toxicity of benzodiazepines in rats". Research communications in chemical pathology and pharmacology 46 (3): 437–447.  
  10. ^ Takeno, S.; Hirano, Y.; Kitamura, A.; Sakai, T. (1993). "Comparative Developmental Toxicity and Metabolism of Nitrazepam in Rats and Mice". Toxicology and Applied Pharmacology 121 (2): 233–238.