How long does Methylnaphthidate last?

The total duration of Methylnaphthidate via insufflated is 1.5 hours to 3 hours. Onset typically occurs within 3 minutes to 6 minutes. Peak effects last 1 hour to 2 hours.

Methylnaphthidate — SubstanceWiki

Stimulant drug

HDMP-28 or methylnaphthidate is a stimulant drug of the piperidine and naphthylaminopropane groups, closely related to methylphenidate (Ritalin), but with the benzene ring replaced by naphthalene. It is a potent dopamine reuptake inhibitor, with several times the potency of methylphenidate and a short duration of action, and is a structural isomer of another potent dopamine reuptake inhibitor, N,O-Dimethyl-4-(2-naphthyl)piperidine-3-carboxylate. It has been sold as a designer drug since around 2015.

Most of the TMP analogs of HDMP-28 have SERT Ki values in the range >10,000 and so are selective for dopamine and noradrenaline reuptake, with little or no effect on serotonin. HDMP-28 has high affinity to SERT, and so behaves as a triple reuptake inhibitor.

D.R. is the discrimination ratio = [3H]DA÷[3H]CFT.

A low D.R. indicates more addictive, whereas a high D.R. indicates low propensity for self-administration.

How It Feels

Methylnaphthidate introduces itself with the same clinical precision as other members of the phenidate family. Within twenty to forty minutes of oral ingestion, attention sharpens and the ambient noise of unfocused thought begins to quiet. There is no dramatic onset, no rush, no euphoria. Instead, there is a subtle but measurable improvement in the ability to concentrate, prioritize, and follow through on tasks. The world does not change. The mind's capacity to engage with it simply improves.

At the peak, reached around one to two hours in, the experience is one of clean, focused productivity. Working memory functions well. The ability to sustain attention on a single task for extended periods is enhanced. There is a mild increase in motivation, a quiet sense that tasks are worth completing and that the energy to complete them is available. The cognitive enhancement is moderate, falling somewhere between the gentler racetams and the more aggressive amphetamines. Socially, there may be a slight increase in verbal fluency and confidence, but the compound is fundamentally nonsocial in its character.

Physical effects are minimal and predictable. Mild tachycardia, reduced appetite, and slight dryness of the mouth constitute the bulk of the somatic experience. The body remains comfortable and functional throughout. There is no significant jaw tension, no vasoconstriction of note, and no temperature dysregulation. This physical gentleness is part of what makes methylnaphthidate suitable for its intended use as a functional cognitive enhancer.

The duration is moderate, with primary effects lasting three to five hours. The offset is gradual, a slow dimming of the enhanced focus rather than a sudden drop. There is no significant rebound or crash. Appetite returns, fatigue creeps back in at its normal pace, and sleep is achievable within a reasonable timeframe. The morning after is unremarkable. As with other functional phenidates, the experience is defined not by what it adds to consciousness but by what it quietly removes: the friction between intention and execution, the inertia that makes starting difficult, the drift that makes sustaining attention a chore.

Subjective Effects

The effects listed below are based on the Subjective Effect Index (SEI), an open research literature based on anecdotal reports and personal analyses. They should be viewed with a healthy degree of skepticism. These effects will not necessarily occur in a predictable or reliable manner, although higher doses are more liable to induce the full spectrum of effects.

Physical Effects

Physical(8)

Appetite suppression— A distinct decrease in hunger and desire to eat, ranging from reduced interest in food to complete d...
Dehydration— A state of insufficient bodily hydration manifesting as persistent thirst, dry mouth, and physical d...
Increased heart rate— A noticeable acceleration of heartbeat that can range from a subtle awareness of one's pulse to a fo...
Respiratory depression— A dangerous slowing and shallowing of breathing that can progress from barely noticeable reductions ...
Seizure— Uncontrolled brain electrical activity causing convulsions and loss of consciousness -- a life-threa...
Stimulation— A state of heightened physical and mental energy characterized by increased wakefulness, elevated mo...
Teeth grinding— An involuntary clenching and rhythmic grinding of the jaw muscles, known clinically as bruxism, that...
Vasoconstriction— A narrowing of blood vessels throughout the body that produces sensations of cold extremities, tingl...

Cognitive & Perceptual Effects

Cognitive(12)

Analysis enhancement— A perceived improvement in one's ability to logically deconstruct concepts, recognize patterns, and ...
Anxiety— Intense feelings of apprehension, worry, and dread that can range from a subtle background unease to...
Cognitive fatigue— Mental exhaustion and difficulty sustaining thought after intense cognitive experiences, common duri...
Depression— A persistent state of low mood, emotional numbness, hopelessness, and diminished interest or pleasur...
Focus enhancement— An enhanced ability to direct and sustain attention on a single task or stimulus with unusual clarit...

Pharmacology

Methylnaphthidate is thought to act primarily as a monoamine triple reuptake inhibitor, meaning it effectively elevates the levels of dopamine, noradrenaline and serotonin neurotransmitters throughout the brain and CNS by binding to and partially blocking the transporter proteins that normally clear out these monoamines from the synaptic cleft. This allows these molecules to accumulate throughout the brain, particularly within the reward pathways in the brain, resulting in stimulating and euphoric effects.

The toxicity and long-term health effects of recreational methylnaphthidate use do not seem to have been studied in any scientific context and the exact toxic and lethal dosages are unknown. This is because methylnaphthidate is a research chemical with very little history of human usage. Anecdotal evidence from people who have tried methylnaphthidate suggests that there are no negative health effects attributed to simply trying the drug by itself at low to moderate doses and using it very sparingly (but nothing can be completely guaranteed). Independent researchshould always be done to ensure that a combination of two or more substances is safe before consumption.

It is strongly recommended that one use harm reduction practices when using this drug.

In terms of its tolerance, methylnaphthidate can be used multiple days in a row for extended periods of time, but acute tolerance does exist and builds up gradually over repeated extended use. This results in the user requiring an increase in dosage to achieve the same effects.

While generally considered less recreational, methylnaphthidate has potential for abuse on par with that of amphetamine, cocaine or methylphenidate due to its lack of significant tolerance, euphoric effects and action upon dopamine and serotonin transporters. -MDMA** - The neurotoxic effects of MDMA may be increased when combined with other stimulants. -Cocaine** - This combination may synergistically increase strain on the heart to dangerous degrees.

Germany: HDMP-28 is controlled under the NpSG (New Psychoactive Substances Act) as of November 26, 2016. Production and import with the aim to place it on the market, administration to another person and trading is punishable. Possession is illegal but not penalized.
Switzerland: HDMP-28 is a controlled substance specifically named under Verzeichnis E. It was added to the list of controlled substances in December 2015.
Turkey: HDMP-28 is illegal in Turkey as of February 2016.
United Kingdom: HDMP-28 is a class B drug in the UK as of 31st May 2017 and is illegal to possess, produce or supply.
United States: HDMP-28 is not explicitly controlled in the US, but it could possibly be considered an analog of a Schedule II substance (methylphenidate) under the Federal Analog Act.
Responsible use
Research chemical
Stimulant
Methylphenidate
Ethylphenidate
Isopropylphenidate
HDMP-28 (Wikipedia)
HDMP-28 (Isomer Design)
HDMP-28 (Bluelight)

Detection Methods

Standard Drug Panel Inclusion

Methylnaphthidate is a phenidate-class stimulant that is not detected on standard 5-panel, 10-panel, or 12-panel immunoassay drug screens. Phenidates are structurally distinct from amphetamines and do not cross-react with amphetamine or methamphetamine antibodies used in commercial immunoassays. There is no dedicated phenidate channel on any standard workplace or clinical drug panel.

Urine Detection

Methylnaphthidate and its primary metabolite ritalinic acid (or the corresponding deesterified acid analogue) can be detected in urine for approximately 1 to 3 days after a single oral dose. The ester bond in phenidate compounds is rapidly hydrolyzed by plasma and hepatic esterases, producing the corresponding acid metabolite which is the dominant species found in urine. Higher doses or repeated administration may extend the detection window modestly.

Blood and Saliva Detection

Blood concentrations of Methylnaphthidate decline rapidly due to ester hydrolysis, with a detection window of approximately 6 to 24 hours for the parent compound. The acid metabolite persists longer in plasma, detectable for up to 48 hours. Oral fluid testing can detect the parent compound for approximately 12 to 36 hours, though this route of detection is rarely employed for phenidates in practice.

Hair Follicle Detection

Hair follicle analysis may detect Methylnaphthidate or its metabolites for up to 90 days. However, incorporation of phenidate-class compounds into hair has not been extensively studied, and commercial laboratories do not routinely test for these substances. Specialized forensic laboratories with LC-MS/MS capability and appropriate reference standards would be required.

Confirmatory Testing

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is the gold standard for confirming the presence of Methylnaphthidate and its metabolites. The ester bond in phenidates makes them somewhat labile under GC-MS conditions, so LC-MS/MS is preferred. Both parent compound and the deesterified acid metabolite should be targeted for comprehensive analysis.

Reagent Testing

Marquis reagent typically shows no reaction or a very faint color change with Methylnaphthidate, which helps distinguish it from amphetamines (orange-brown) and MDMA (purple-black). Mecke reagent generally shows no reaction. Mandelin reagent may produce a faint yellow or no change. The absence of strong reagent reactions is characteristic of the phenidate class and is itself a useful piece of information when combined with other reagent results.

Interactions

Substance	Status	Note
25x-NBOH	Dangerous	—
25x-NBOMe	Dangerous	—
Atropa belladonna	Dangerous	Extreme cardiovascular strain from anticholinergic and stimulant effects combined
Cocaine	Dangerous	—
Datura	Dangerous	Extreme cardiovascular strain from anticholinergic and stimulant effects combined
Diphenhydramine	Dangerous	Extreme cardiovascular strain from anticholinergic and stimulant effects combined
Harmala alkaloid	Dangerous	Risk of hypertensive crisis and serotonin syndrome; potentially fatal combination
MDMA	Dangerous	—
Peganum harmala	Dangerous	Risk of hypertensive crisis and serotonin syndrome; potentially fatal combination
1,3-Butanediol	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
25E-NBOH	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
2C-T	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
2C-T-2	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
2C-T-21	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
2C-T-7	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
3-FMA	Caution	Increased cardiovascular strain and neurotoxicity risk
4-MMC	Caution	Increased cardiovascular strain and neurotoxicity risk
8-Chlorotheophylline	Caution	Increased cardiovascular strain and neurotoxicity risk
Adrafinil	Caution	Increased cardiovascular strain and neurotoxicity risk
Allylescaline	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
Ayahuasca	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
Benzydamine	Caution	Increased cardiovascular strain and neurotoxicity risk
Bromantane	Caution	Increased cardiovascular strain and neurotoxicity risk
Cake	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
Deschloroetizolam	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
Desomorphine	Caution	Stimulants mask opioid sedation, increasing overdose risk when the stimulant wears off
DET	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
Dichloropane	Caution	Increased cardiovascular strain and neurotoxicity risk
Diclazepam	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
DiPT	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
DOM	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
DPT	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
Efavirenz	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
Ephedrine	Caution	Increased cardiovascular strain and neurotoxicity risk
EPT	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
Eszopiclone	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
Etizolam	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
Flubromazepam	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
Flubromazolam	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
Flunitrazepam	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
Flunitrazolam	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
Gaboxadol	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
Hexedrone	Caution	Increased cardiovascular strain and neurotoxicity risk
Ibogaine	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
Lorazepam	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
Mephenaqualone	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
MET	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
Methallylescaline	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
Methcathinone	Caution	Increased cardiovascular strain and neurotoxicity risk
Metizolam	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
Midazolam	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
MiPT	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
MPT	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
Naloxone	Caution	Stimulants mask opioid sedation, increasing overdose risk when the stimulant wears off
Nicotine	Caution	Increased cardiovascular strain and neurotoxicity risk
Nifoxipam	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
Oxiracetam	Caution	Increased cardiovascular strain and neurotoxicity risk
Pentobarbital	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
Phenobarbital	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
Phenylpiracetam	Caution	Increased cardiovascular strain and neurotoxicity risk
Psilocybin Mushrooms	Caution	Increases anxiety, cardiovascular stress, and psychological intensity
Rhodiola Rosea	Caution	Increased cardiovascular strain and neurotoxicity risk
SAMe	Caution	Masks the effects of each drug; risk of overdosing when one wears off before the other
Alcohol	Uncertain	—

Showing 64 key interactions out of 65 total.

Toxicity & Safety

Further information: Research chemicals § Toxicity and harm potential The toxicity and long-term health effects of recreational methylnaphthidate use do not seem to have been studied in any scientific context and the exact toxic and lethal dosages are unknown. This is because methylnaphthidate is a research chemical with very little history of human usage. Anecdotal evidence from people who have tried methylnaphthidate suggests that there are no negative health effects attributed to simply trying the drug by itself at low to moderate doses and using it very sparingly (but nothing can be completely guaranteed). Independent researchshould always be done to ensure that a combination of two or more substances is safe before consumption.

It is strongly recommended that one use harm reduction practices when using this drug.

Tolerance and addiction potential

Dangerous interactions

Warning: Many psychoactive substances that are reasonably safe to use on their own can suddenly become dangerous and even life-threatening when combined with certain other substances. The following list provides some known dangerous interactions (although it is not guaranteed to include all of them).

Always conduct independent research (e.g. Google, DuckDuckGo, PubMed) to ensure that a combination of two or more substances is safe to consume. Some of the listed interactions have been sourced from TripSit.

25x-NBOMe & 25x-NBOH - 25x compounds are highly stimulating and physically straining. Combinations with Methylnaphthidate should be strictly avoided due to the risk of excessive stimulation and heart strain. This can result in increased blood pressure, vasoconstriction, panic attacks, thought loops, seizures, and heart failure in extreme cases.
Alcohol - Combining alcohol with stimulants can be dangerous due to the risk of accidental over-intoxication. Stimulants mask alcohol's depressant effects, which is what most people use to assess their degree of intoxication. Once the stimulant wears off, the depressant effects will be left unopposed, which can result in blackouts and severe respiratory depression. If mixing, the user should strictly limit themselves to only drinking a certain amount of alcohol per hour.
DXM - Combinations with DXM should be avoided due to its inhibiting effects on serotonin and norepinephrine reuptake. There is an increased risk of panic attacks and hypertensive crisis, or serotonin syndrome with serotonin releasers (MDMA, methylone, mephedrone, etc.). Monitor blood pressure carefully and avoid strenuous physical activity.
MDMA - Any neurotoxic effects of MDMA are likely to be increased when other stimulants are present. There is also a risk of excessive blood pressure and heart strain (cardiotoxicity).
MXE - Some reports suggest combinations with MXE may dangerously increase blood pressure and increase the risk of mania and psychosis.
Dissociatives - Both classes carry a risk of delusions, mania and psychosis, and these risk may be multiplied when combined.
Stimulants - Methylnaphthidate may be dangerous to combine with other stimulants like cocaine as they can increase one's heart rate and blood pressure to dangerous levels.
Tramadol - Tramadol is known to lower the seizure threshold and combinations with stimulants may further increase this risk.
MAOIs - This combination may increase the amount of neurotransmitters such as serotonin to dangerous or even fatal levels. Examples include syrian rue, banisteriopsis caapi, and some antidepressants.
MDMA - The neurotoxic effects of MDMA may be increased when combined with other stimulants.
Cocaine - This combination may synergistically increase strain on the heart to dangerous degrees.

Overdose Information

Stimulant overdose from Methylnaphthidate is a medical emergency primarily involving cardiovascular and neurological toxicity.

Signs of overdose: Extremely rapid or irregular heartbeat, chest pain, severe headache, dangerously elevated body temperature, seizures, agitation progressing to psychosis, confusion, and loss of consciousness.Emergency response:

Call emergency services immediately
Keep the person cool (remove excess clothing, apply cool water)
If seizures occur, protect the head and clear the area of hard objects
If the person loses consciousness, place in recovery position
Do not give the person more stimulants, caffeine, or depressants unless directed by medical professionalsPrevention: Pre-measure doses. Avoid redosing. Stay hydrated (but don't overhydrate). Take breaks from physical activity. Monitor heart rate if possible. Have someone present who can recognize warning signs.

Full	Unknown
Half	Unknown
Zero	Unknown

Methylnaphthidate

Quick Dosage

Dosage

insufflated

oral

Duration

insufflated

oral

How It Feels

Subjective Effects

Physical Effects

Physical(8)

Cognitive & Perceptual Effects

Cognitive(12)

Pharmacology

Detection Methods

Standard Drug Panel Inclusion

Urine Detection

Blood and Saliva Detection

Hair Follicle Detection

Confirmatory Testing

Reagent Testing

Interactions

History

Harm Reduction

Toxicity & Safety

Overdose Information

Dangerous Interactions

Tolerance

Legal Status

Experience Reports (2)

Tips (4)

See Also

References (5)

Frequently Asked Questions