(marketed under brand name
) is an intermediate-acting hypnotic
drug which is a benzodiazepine
derivative. It was first
synthesized in Japan in
It possesses hypnotic
, and skeletal muscle relaxant
properties. Nimetazepam is also an anticonvulsant
. It is sold in 5 mg tablets
known as Erimin. It is generally prescribed for the treatment of
short-term severe or debilitating 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).
Nimetazepam has a reputation for being particularly subject to
abuse (known as 'Happy 5', sold as an Ecstasy replacement without a
hangover), especially by persons addicted to amphetamines
reason it is no longer sold in most Western nations, but is still a
significant drug of abuse in some Asian countries such as Japan and Malaysia.
Nimetazepam is subject to legal restrictions in Malaysia, and due
to its scarcity, many tablets sold on the black market are in fact
counterfeits containing other benzodiazepines such as diazepam
instead. The Central Narcotics
of Singapore seized 94,200 nimetazepam tablets in 2003.
This is the largest nimetazepam seizure recorded since nimetazepam
became a controlled drug under the Misuse of Drugs Act in 1992.
Together with temazepam abusers, they accounted for 47% of the
abusers arrested in 2005. In Japan, where
seizures of diverted nimetazepam are mostly concentrated, it
remains as a major drug of abuse. Seizures of the drug
in Thailand, Malaysia, Singapore, Laos, Hong Kong, and Indonesia are also common.
The drug is usually
exported from Japan, where the drug is legal by prescription for
insomnia. Japanese organized crime syndicates control the
distribution of nimetazepam and to a lesser extent, flutoprazepam
, all of which are the most
heavily controlled and most in demand benzodiazepines throughout
and Southeast Asia
Darke, Ross & Hall found that nimetazepam was rated extremely
high by drug abusers, rating second only to temazepam
among benzodiazepines. The two most
common reasons for this preference were that it was the ‘strongest’
and that it gave a good ‘high’.
Nimetazepam is currently a
drug under the international Convention on Psychotropic
Singapore, nimetazepam is banned under the Misuse of Drugs Act.
The illegal possession or consumption of nimetazepam is punishable
by up to ten years of imprisonment, a fine of 20,000 Singapore dollars
, or both; illegally
importing or exporting nimetazepam is punishable by up to 20 years
of imprisonment and caning
Kong, nimetazepam is regulated under Schedule 1 of
Kong's Chapter 134 Dangerous Drugs
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.
In a rat study Nimetazepam showed greater damage to the fetus, as
when compared against
other benzodiazepines, all at a dosage of 100mg/kg. Diazepam
however showed relatively weak fetal
toxicities. 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.
- DEA Resources, Microgram Journal, Volume 2, Numbers
1-4, January-December 2004
- Devaney, M., Reid, G. and Baldwin, S., 2006. Situational
analysis of illicit drug issues and responses in the Asia-Pacific
region, Research Paper 12. Australian National Council on Drugs,
- Annual Estimates Of Requirements Of Narcotic Drugs,
Manufacture Of Synthetic Drugs, Opium Production And Cultivation Of
- http://www.cnb.gov.sg/ [Central Narcotics Bureau,