MT-45 is an opioid that’s been used for a few years, with it primarily coming from online research chemical providers. The drug does have some pleasant opioid effects, but it’s usually not described as an ideal and truly enjoyable drug. Other opioids are almost always preferred.

It was developed in the 1970s by a Japanese pharmaceutical company. Outside of a small amount of research in animals, it has little/no history prior to the early 2010s. Since 2013, online vendors have sold it and reports of its effects have grown.

While MT-45 has been used like other RC opioids, most users tend to abandon it upon finding it has too many negative effects and/or too few positive effects relative to other drugs. So long as a common dose is used, it doesn’t appear to be particularly harmful acutely. But, reports of persistent hearing loss and possible hair loss suggest it’s not wise to use on any regular basis or at strong+ doses, which applies to many RCs in general.

MT-45 = IC-6; 1-Cyclohexyl-4-(1,2-diphenylethyl)piperazine



Light: 30 – 45 mg

Common: 45 – 60 mg

Strong: 60+ mg



Total: 6 – 12 hours (many reports of it lasting 10-12 hours)

Onset: 00:30 – 00:45 (some reports of 1-2 hour onsets)


Total: 2 – 3 hours

Onset: Under 15 minutes

Experience Reports




  • Calmness
  • Pain relief
  • Feelings of warmth
  • Sedation
  • Relaxation
  • General sense of well-being
  • Euphoria


  • Itching
  • Nausea, vomiting
  • Vision impairment
  • Dizziness
  • Muscle twitching
  • Sweating
  • Anxiety
  • Insomnia
  • Impaired coordination

MT-45 produces mild opioid effects and, at best, is described as similar to codeine or methadone. It either lacks euphoria or produces just a fraction of what an opioid like morphine or heroin can provide.

The effects are a cross of normal opioid activity and dissociative activity. It’s occasionally been described as closer to a low-dose dissociative than an opioid.

MT-45 doesn’t appear to produce as much sedation as other opioids at low-common doses and it has a less significant miotic (pupil constriction) effect. When an overdose occurs, initial responders may have a harder time recognizing it as an opioid overdose due to the lack of miotic action in many users.

Users generally report disliking the substance and it appears few people continue using it for extended periods of time. However, addiction is still possible.

Some people have found it can alleviate opioid withdrawal, which is to be expected.

There can be a desire to redose before the drug kicks in and during the comedown. In both cases, impulsive redosing should be avoided, especially given the notable possibility of a life-threatening overdose.

Pharmacology & Chemistry

As a piperazine derivative, MT-45 has a structure that’s distinct from other opioids. It’s a chiral molecule which has an R and an S isomer.

The racemic mixture has a similar potency to morphine for analgesic effects. The S isomer of MT-45 is more potent and seems to be responsible for much of the racemic mixture’s activity.

S-MT-45 is a stronger analgesic, appears to be a more potent u-opioid agonist, and has a higher affinity for k-opioid and d-opioid receptors.

The R-isomer does have some u-opioid agonist activity, but it’s less significant. The R-isomer may also have antagonist properties at Sigma 1 and Sigma 2 receptors, since certain activities in mice are reversed by sigma agonists.


MT-45 was created by Dainippon Pharmaceutical Co., a Japanese pharmaceutical company, in the 1970s. Dainippon was investigating drugs structurally similar to perathiepine (an antipsychotic) and lefetamine (an analgesic with stimulant properties.)

Of the drugs created, MT-45 was deemed important because early tests found it was nearly as potent as morphine for analgesia.

Come 2013, the drug appeared on a number of research chemical sites, alongside synthetic cannabinoids, synthetic cathinones, and other substances.

Most users have been males aged 16-40 (particularly 20-35). Due to the way it’s been sold and its frequent co-administration with other RCs, it seems MT-45 has largely been confined to the RC drug scene.

Companies located in Canada, Japan, India, China, and the EU have sold the substance. China appears to be the primary source country.

How To Use

Oral is the most popular route of administration, but intranasal, IV/IM, and rectal administration have also been reported.

For naive users, an oral dose of 50 mg is normal, whereas tolerant users have reported using up to 200-250 mg.


  • Light: 30 – 45 mg
  • Common: 45 – 50 mg
  • Strong: 60+ mg

Legal Status

MT-45 is not currently illegal in the United States.

It is illegal in the United Kingdom and Czech Republic.


Deaths have been attributed to MT-45 used by itself and with other drugs. A number of deaths have come from combinations including substances like etizolam, ethanol, pyrazolam, and flubrazolam. Combining it with other depressants isn’t wise.

At low-common doses, it doesn’t appear to be particularly dangerous for healthy people, but (at most) that applies to acute usage.

Based on the deaths that have been documented, MT-45 overdoses (both fatal and non-fatal) can produce the following:

  • Unconsciousness
  • Coma
  • Respiratory depression
  • Tachycardia
  • Drowsiness
  • Hypoxia & cyanosis

Deaths from large doses of MT-45 are entirely possible and it’s not clear how much can be used safely.

In the case of an overdose, naloxone is at least partially efficacious. It can reverse the effects of MT-45 to a sufficient extent in many users, but it sometimes takes multiple doses to produce adequate reversal.

Auditory Issues and Ototoxicity

Opioids are known to be capable of causing auditory issues. Lasting or severe hearing loss is rare, but there is clearly a mechanism by which opioids can cause auditory issues in some people.

MT-45 produces auditory issues in what seems to be a far more reliable manner. Anecdotal reports state the drug can cause tinnitus and hearing loss. In documented cases, those who’ve experienced overdoses sometimes come out of the overdose reporting transient hearing loss.

In one documented case, persistent bilateral hearing loss was reported. By their two week follow-up, the hearing loss was still a problem, suggesting it could be very long-lasting or permanent.

How MT-45 causes hearing loss or tinnitus isn’t known, but the sheer number of reports means it’s a notable concern for anyone using the drug regularly or at high doses. Because of what’s been reported, some form of ototoxicity seems to exist.

Combos To Avoid

MT-45 should not be combined with other depressants (e.g. benzodiazepines, alcohol) due to the possibility of severe respiratory depression, vomiting, and unconsciousness.

For similar reasons, dissociatives like ketamine, MXE, and DXM should be avoided.

Due to the lack of information, it’s wise to avoid other combinations as well.


(2016) Analysis of MT-45, a Novel Synthetic Opioid, in Human Whole Blood by LC-MS-MS and Its Identification in a Drug-Related Death.

(2015) Understanding the availability, prevalence of use, desired effects, acute toxicity and dependence potential of the novel opioid MT-45.

(2014) MT-45, a new psychoactive substance associated with hearing loss and unconsciousness.

(2014) MT-45–a dangerous and potentially ototoxic internet drug

(2014) MT-45: EMCDDA-Europol Joint Report

(2013) Identification of two new-type designer drugs, piperazine derivative MT-45 (I-C6) and synthetic peptide Noopept (GVS-111), with synthetic cannabinoid A-834735, cathinone derivative 4-methoxy-α-PVP, and phenethylamine derivative 4-methylbuphedrine from illegal products

(1976) Comparative study of 1-cyclohexyl-4-(1,2-diphenylethyl)-piperazine and its enantiomorphs on analgesic and othe pharmacological activities in experimental animals.

Test Results






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