|Summary sheet: Phenmetrazine|
|Routes of Administration|
Phenmetrazine (also known as Preludin among many others) is a stimulant substance of the substituted amphetamine chemical class. It produces classical stimulant effects which includes stimulation, focus & motivation enhancement, thought acceleration, wakefulness, and euphoria when administered.
Phenmetrazine was first patented in Germany in 1952 by Boehringer-Ingelheim, with some pharmacological data published in 1954. It was the result of a search by Thomä and Wick for an anorectic drug without the side-effects of amphetamine.
In clinical use, phenmetrazine produces less nervousness, hyperexcitability, euphoria and insomnia than drugs of the amphetamine family. It tends not to increase heart rate as much as other stimulants. Due to the relative lack of side effects, one study found it well tolerated in children.
Phenmetrazine was clinically used in Europe as an anorectic (weight-loss agent) in the 1950s. It was later withdrawn due to concerns over misuse and addiction stemming from widespread recreational use. While replaced by its prodrug phendimetrazine, it is now rarely prescribed due to similar concerns of abuse and addiction.
Today, phenmetrazine is no longer produced and has been superseded by amphetamine in both its pharmaceutical and street forms, as well as by its research chemical analog 3-fluorophenmetrazine (3-FPM).
Phenmetrazine is a synthetic molecule of the amphetamine family. Molecules of the amphetamine class contain a phenethylamine core featuring a phenyl ring bound to an amino (NH2) group through an ethyl chain with an additional methyl substitution at Rα. Amphetamines are alpha-methylated phenethylamines.
Phenmetrazine is comprised of an amphetamine skeleton that has been incorporated into a morpholine ring. At R2 of its chain, an oxygen group is bound -- this oxygen group is linked by an ethyl chain to the terminal amine of the amphetamine chain to form a morpholine group.
Phenmetrazine is the parent compound of the popular research chemical 3-fluorophenmetrazine.
Phenmetrazine acts as a releasing agent of norepinephrine and dopamine with EC50 values of 50.4 ± 5.4 nM and 131 ± 11 nM, respectively. It has negligible efficacy as a releaser of serotonin, with an EC50 value of only 7,765 ± 610 nM. This accumulation of neurotransmitters in the synaptic cleft results in its euphoric and stimulating effects.
After an oral dose, about 70% of the drug is excreted from the body within 24 hours. About 19% of that is excreted as the unmetabolized drug and the rest as various metabolites.
In trials performed on rats, it has been found that after subcutaneous administration of phenmetrazine, both optical isomers are equally effective in reducing food intake, but in oral administration the levo isomer is more effective. In terms of central stimulation, however, the dextro isomer is about 4 times as effective in both methods of administration.
Disclaimer: The effects listed below cite the Subjective Effect Index (SEI), a literature based on anecdotal reports and the personal experiences of PsychonautWiki contributors. As a result, they should be treated with a healthy amount of skepticism. It is worth noting that these effects will not necessarily occur in a consistent or reliable manner, although higher doses are more likely to induce the full spectrum of effects. Likewise, adverse effects become much more likely with higher doses and may include serious injury or death.
- Stimulation - In terms of its effects on the physical energy levels of the user, phenmetrazine is usually considered to be mildly to moderately energetic and stimulating in a fashion that is considerably weaker in comparison to that of traditional recreational stimulants such as amphetamine, MDMA or cocaine. This encourages physical activities such as performing chores and repetitive tasks which would otherwise be boring and strenuous physical activities.
- Increased heart rate - In comparison to other stimulants such as amphetamine or cocaine, phenmetrazine only has a mild effect on one's heart rate.
- Increased blood pressure
- Stamina enhancement
- Appetite suppression - The above components are also accompanied by a suppression of appetite which is usually much less intense in strength in comparison to the appetite suppression experienced with amphetamine or methamphetamine.
- Increased perspiration
- Frequent urination
- Dry mouth
- Vasoconstriction 
- Increased libido - Phenmetrazine has been reported to enhance sex drive and improve sexual performance.
- Pupil dilation
- Teeth grinding - This component can be considered to be less intense when compared with that of MDMA and many other stimulants.
- Analysis enhancement
- Disinhibition - While phenmetrazine is often noted for its potential functional applications, higher doses can result in the kind of disinhibition seen in traditional stimulants like amphetamine or cocaine, leading to increased sociability.
- Cognitive euphoria - This component is much less intense than the euphoria experienced with other stimulants such as amphetamine, cocaine, or methamphetamine.
- Ego inflation
- Focus enhancement - This component is most effective at low to moderate doses as anything higher will usually impair concentration.
- Motivation enhancement - This component is experienced in a functional form even at moderate to high doses.
- Immersion enhancement
- Increased music appreciation
- Thought acceleration
- Time compression - This can be described as the experience of time speeding up and passing much quicker than it usually would when sober.
- The effects which occur during the offset of a stimulant experience generally feel negative and uncomfortable in comparison to the effects which occurred during its peak. This is often referred to as a "comedown" and occurs because of neurotransmitter depletion. Its effects commonly include:
There are currently no anecdotal reports which describe the effects of this compound within our experience index. Additional experience reports can be found here:
Toxicity and harm potential
This toxicity and harm potential section is a stub.
As such, it may contain incomplete or even dangerously wrong information. You can help by expanding or correcting it.
The toxicity and long-term health effects of recreational phenmetrazine use do not seem to have been studied in any scientific context and the exact toxic dosage is unknown.
It is strongly recommended that one use harm reduction practices when using this substance.
Tolerance and addiction potential
As with other stimulants, the chronic use of phenmetrazine can be considered moderately addictive with a high potential for abuse and is capable of causing psychological dependence among certain users. When addiction has developed, cravings and withdrawal effects may occur if a person suddenly stops their usage.
Tolerance to many of the effects of phenmetrazine develops with prolonged and repeated use. This results in users having to administer increasingly large doses to achieve the same effects. After that, it takes about 3 - 7 days for the tolerance to be reduced to half and 1 - 2 weeks to be back at baseline (in the absence of further consumption). Phenmetrazine presents cross-tolerance with all dopaminergic stimulants, meaning that after the consumption of phenmetrazine all stimulants will have a reduced effect.
Although many psychoactive substances are reasonably safe to use on their own, they can quickly become dangerous or even life-threatening when combined with other substances. The list below includes some known dangerous combinations (although it cannot be guaranteed to include all of them). Independent research (e.g. Google, DuckDuckGo) should always be conducted to ensure that a combination of two or more substances is safe to consume. Some interactions listed have been sourced from TripSit.
- Stimulants - Phenmetrazine can be potentially dangerous in combination with other stimulants as it can increase one's heart rate and blood pressure to dangerous levels.
- 25x-NBOMe & 25x-NBOH - Members of the 25x family are highly stimulating and physically straining. Combinations with stimulants should be avoided due to the risk of excessive stimulation. This can result in panic attacks, thought loops, seizures, increased blood pressure, vasoconstriction, and heart failure in extreme cases.
- Alcohol - Alcohol can be dangerous to combine with stimulants due to the risk of accidental over-intoxication. Stimulants mask the sedative effects of alcohol, which is the main factor people use to assess their degree of intoxication. Once the stimulant wears off, the depressant effects of alcohol are left unopposed, which can result in blackouts and respiratory depression. If combined, one should strictly limit themselves to only drinking a certain amount of alcohol per hour.
- DXM - Combinations with DXM should be handled with extreme care due to DXM's effects on serotonin and norepinephrine reuptake. This can lead to panic attacks, hypertensive crisis, or serotonin syndrome with stimulants that increase levels of serotonin (MDMA, methylone, mephedrone, etc.). Monitor blood pressure carefully and avoid strenuous physical activity.
- MDMA - The neurotoxic effects of MDMA may be increased when combined with other stimulants. There is also a risk of excessive heart strain.
- MXE - Combinations with MXE may dangerously elevate blood pressure and increase the risk of psychosis.
- Stimulants - Phenmetrazine can be potentially dangerous in combination with other stimulants like cocaine as they can increase one's heart rate and blood pressure to dangerous levels.
- Tramadol - Tramadol lowers the seizure threshold. Combinations with stimulants may further increase this risk.
- MDMA - The neurotoxic effects of MDMA may be increased when combined with amphetamines and related compounds like the phenmetrazines.
- MAOIs - This combination may increase the amount of neurotransmitters such as dopamine to dangerous or even fatal levels. Examples include syrian rue, banisteriopsis caapi, and some antidepressants.
- Cocaine - This combination may increase strain on the heart to dangerous levels.
This legality section is a stub.
As such, it may contain incomplete or wrong information. You can help by expanding it.
- Albert Boehringer; Ernst Boehringer. Improvements in or relating to the preparation of substituted morpholines. GB773780.
- US Patent 2835669 - Process for the Production of Substituted Morpholines
- Thomä, O & Wick, H (1954). "Über einige Tetrahydro-1,4-oxazine mit sympathicomimetischen Eigenschaften". Arch. Exp. Pathol. Pharmakol. 222: 540.
- "Phenmetrazine Hydrochloride". J. Am. Med. Assoc. 163 (5): 357. 1957.
- Martel, Antonio (1957). "Preludin (Phenmetrazine) in the Treatment of Obesity". Can. Med. Assoc. J. 76 (2): 117–20. PMC 1823494 Freely accessible. PMID 13383418.
- Kalant, Oriana Josseau (1966). The Amphetamines: Toxicity and Addiction. ISBN 0-398-02511-8.
- Rothman RB, Baumann MH (2006). "Therapeutic potential of monoamine transporter substrates". Current Topics in Medicinal Chemistry. 6 (17): 1845–59. PMID 17017961. https://doi.org/10.2174/156802606778249766.
- Anthony C Moffat, M David Osselton and Brian Widdop. Clarke's Analysis of Drugs and Poisons. ISBN 0-85369-473-7.
- Engelhardt, A (1961). "Studies of the Mechanism of the Anti-Appetite Action of Phenmetrazine". Biochem. Pharmacol. 8 (1): 100. doi:10.1016/0006-2952(61)90520-2.
- Talaie, H.; Panahandeh, R.; Fayaznouri, M. R.; Asadi, Z.; Abdollahi, M. (2009). "Dose-independent occurrence of seizure with tramadol". Journal of Medical Toxicology. 5 (2): 63–67. doi:10.1007/BF03161089. eISSN 1937-6995. ISSN 1556-9039. OCLC 163567183.
- Gillman, P. K. (2005). "Monoamine oxidase inhibitors, opioid analgesics and serotonin toxicity". British Journal of Anaesthesia. 95 (4): 434–441. doi: . eISSN 1471-6771. ISSN 0007-0912. OCLC 01537271. PMID 16051647.