A-PHP
α-pyrrolidinohexiophenone
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α-PHP (α-pyrrolidinohexanophenone) is a synthetic stimulant of the pyrovalerone cathinone class. It is the direct chain-extended successor to α-PVP ("flakka"), with a longer duration of action. It blocks dopamine and norepinephrine reuptake in the brain, flooding reward circuits with dopamine and driving intense euphoria and stimulation.[1][2]
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The pyrovalerone chemical family was patented in the United States in 1967 as a potential medication, but no compound reached clinical development.[3] α-PHP entered the Japanese illicit market in 2014 as a scheduling-evasion successor to α-PVP — a deliberate structural change to stay one step ahead of drug law.[4] It is now controlled under UN Schedule II (2020) and US Schedule I (2021), with no recognized medical use.[5]
Subjective effects include intense euphoria, focused energy, wakefulness, psychomotor drive, and a compulsive compulsive redosing urge. The experience is a pure stimulant arc — driven and focused, without the warmth or social ease of serotonergic stimulants — most comparable to cocaine but with a far longer tail. Paranoia, hallucinations, agitation, and prolonged insomnia are characteristic unsought effects, especially at higher doses or with repeated use.
α-PHP has high abuse liability — preclinical models rate its reward-circuit activation as equivalent to cocaine[6] — and causes cardiovascular toxicity including rapid heart rate and muscle breakdown.[7] Its estimated 37-hour half-life means effects and toxicity persist far longer than most stimulants, and psychotic episodes can last days.[8] No clinical trials exist; understanding comes from laboratory studies, animal models, and case reports.
History[edit]
Discovery
The pyrovalerone chemical family was synthesized and patented in the United States in 1967 as a potential medication, but no compound in the series reached clinical development.[3] The ancestor compound, pyrovalerone, had been used briefly as a fatigue treatment before being placed under UN Schedule IV. The family remained obscure until a close structural relative appeared in a 2011 poisoning case, confirming this branch of the cathinone family could cause serious stimulant toxicity.[9]
Market emergence
α-PHP appeared on the Japanese illicit market in 2014, following international attention to α-PVP ("flakka").[4] Its emergence followed a well-established pattern: adding one carbon to the alkyl chain produces a new, temporarily unscheduled compound.[10] Intoxication cases were subsequently documented across Europe through Swedish surveillance[11] and German forensic casework.[12]
Scheduling and current status
The WHO Expert Committee on Drug Dependence recommended Schedule II placement in 2019, effective internationally in 2020.[3][13] The US DEA issued temporary Schedule I placement in 2019, followed by permanent classification in 2021.[5] Research has intensified since scheduling, with the largest clinical case series published in 2023[12] and the first sex-stratified pharmacokinetic study in 2025.[7]
The designation PV7 follows a pyrovalerone series convention counting carbon backbone length from the ketone carbon — PV5 for α-PVP, PV7 for α-PHP. The "alpha" prefix denotes substitution at the α-carbon adjacent to the ketone, shared across the entire pyrrolidinophenone family. α-PHP's positional isomer α-PiHP — identical molecular formula with a branched rather than straight alkyl chain — was separately scheduled under UN Schedule II in 2023, underscoring the regulatory challenge posed by this rapidly evolving cathinone series.
Chemistry[edit]
Structural class
α-PHP belongs to the pyrovalerone subclass of synthetic cathinones, sharing its core structure with α-PVP and related compounds.[13]
It is the direct one-carbon chain extension of α-PVP — replacing α-PVP's propyl chain with a butyl chain — a structural change that enhances its potency at both dopamine and norepinephrine transporters.[1][14] Its molecular formula is C₁₆H₂₃NO, molecular weight 245.36 g/mol.
Pharmacology[edit]
Mechanism of action
α-PHP blocks the DAT and the NET, preventing these neurotransmitters from being cleared from the synapse.[2][15][3] This is pure reuptake inhibitor — like cocaine and MDPV — rather than forcing neurotransmitters out of nerve terminals as amphetamines do.[2][16] α-PHP has no meaningful activity at the SERT,[1][2] which is why it produces none of the social warmth associated with serotonergic stimulants.
Pharmacokinetics
The only human data come from a single case report: an initial blood concentration of 175 ng/mL with an estimated elimination half-life of 37 hours.[8] This is far longer than cocaine (about 1 hour) or amphetamine (10–12 hours), meaning the drug persists in the body for days after a single use. In a larger forensic series of 29 cases, blood concentrations ranged from 1 to 83 ng/mL.[12]
Metabolism
α-PHP is broken down by the liver, primarily through CYP1A2 and CYP2C19 enzymes.[14] At least 11 primary metabolites have been identified in urine and are the main targets in drug testing.[12][17] α-PHP itself does not directly cause DNA damage, but liver-generated metabolites demonstrated mutagenic potential in laboratory assays.[18]
Neuroscience[edit]
Where it acts
α-PHP floods the brain's reward circuits — particularly the nucleus accumbens — with dopamine, the chemical signal the brain uses to mark experiences as worth repeating. Parallel elevation of norepinephrine drives the arousal, vigilance, and physical activation that accompany the high. Preclinical studies show α-PHP lowers brain reward thresholds in rats at levels comparable to cocaine, a validated measure of how strongly a substance activates addiction circuitry.[6]
Why it matters
Dopamine flooded into reward circuits amplifies wanting — the drive to repeat an experience — more than liking — the actual pleasure felt. This asymmetry may explain the compulsive redosing characteristic of pyrovalerone cathinones: the urge intensifies even as the pleasure diminishes.
In vitro studies show α-PHP kills neural stem cells at high concentrations through multiple cell death pathways.[19] The concentrations tested far exceed measured human blood levels, so the relevance to real-world exposure is unknown.
Subjective Effects[edit]
α-PHP produces a pure stimulant experience — intense dopaminergic drive without the social warmth or sensory alteration of serotonergic drugs. The dominant quality is focus and forward momentum, accompanied by a compulsive pull to continue. The experience is propulsive rather than expansive.
It is closest in character to α-PVP and cocaine — sharing the focused euphoria of potent dopamine reuptake inhibitors — but with a far longer commitment. Where cocaine resolves in under an hour, α-PHP's stimulation, insomnia, and dysphoria extend into the following day or beyond.
Effect Grid
At common doses, the full stimulant experience is present: pronounced euphoria with a strong dopaminergic rush, marked psychomotor activation, thought acceleration, and intense focus. Confidence and sociability increase substantially. Music appreciation is enhanced. A sense of purpose and drive dominates the cognitive landscape.
Cardiovascular effects become significant — tachycardia, elevated blood pressure, and sweating are typical. Appetite is strongly suppressed. Jaw tension and bruxism may emerge. Body temperature rises.
Compulsive redosing urges become prominent at this range. The long half-life (estimated 37 hours) means effects persist well beyond the subjective peak, and sleep is impossible for many hours. Functional impairment is substantial.
Modeled from the effect's dose-dependence curve — not per-substance measurements.
Touch enhancement · Brightness alteration · Peripheral misidentification · Auditory distortion · Visual drifting · Visual acuity suppression · Auditory misinterpretation · Touch suppression · Auditory hallucinations · Shadow people · External hallucinations
Visual drifting · Visual acuity suppression · Auditory misinterpretation · Touch suppression · Auditory hallucinations · Shadow people · External hallucinations
Restlessness · Insomnia · Pupil dilation · Dry mouth · Excessive sweating · Body high · Heart rate perception changes · Muscle tension · Physical fatigue · Headache · Bruxism · Dehydration sensation · Spontaneous body sensations · Tactile euphoria · Tingling / electric sensations · Trembling · Nausea · Involuntary body movements · Sexual arousal enhancement · Dizziness · Nasal congestion · Respiratory stimulation · Abnormal heartbeat · Increased urination · Constipation · Nystagmus (eye wobbles) · Vomiting · Seizure threshold reduction · Tactile hallucination
Dry mouth · Excessive sweating · Body high · Heart rate perception changes · Muscle tension · Physical fatigue · Headache · Bruxism · Dehydration sensation · Spontaneous body sensations · Tactile euphoria · Tingling / electric sensations · Trembling · Nausea · Involuntary body movements · Sexual arousal enhancement · Dizziness · Nasal congestion · Respiratory stimulation · Increased urination · Constipation · Nystagmus (eye wobbles) · Vomiting · Seizure threshold reduction · Tactile hallucination
Thought deceleration · Motivation suppression · Cognitive dysphoria · Focus suppression · Focus enhancement · Motivation enhancement · Analysis enhancement · Information processing suppression · Immersion enhancement · Aesthetic enhancement · Cognitive impairment · Information processing enhancement · Multiple thought streams · Thought loops · Confusion · Delusions of sobriety · Memory fragmentation · Pattern recognition enhancement · Thought disorganization · Creativity enhancement · Delusions · Delirium
Focus suppression · Focus enhancement · Motivation enhancement · Analysis enhancement · Information processing suppression · Immersion enhancement · Aesthetic enhancement · Cognitive impairment · Information processing enhancement · Multiple thought streams · Thought loops · Confusion · Memory fragmentation · Pattern recognition enhancement · Thought disorganization · Creativity enhancement · Delusions · Delirium
Anhedonia · Dysphoria · Emotional lability · Mania
Communication enhancement · Sociability enhancement · Social connection · Flow state · Automaticity · Depersonalization · Derealization
Automaticity · Depersonalization · Derealization
Timeline
First alerts emerge as mild wakefulness and subtle mood elevation. A slight increase in heart rate may be perceptible.
Stimulation builds progressively — euphoria, mental clarity, and psychomotor activation develop over 30–60 minutes. Heart rate and blood pressure begin to rise.
Maximum dopaminergic stimulation: intense euphoria, pronounced thought acceleration, strong motivation, and marked psychomotor activation. Cardiovascular effects (tachycardia, hypertension) are most pronounced. Compulsive redosing urges are strongest during and immediately after this phase.
Euphoria diminishes while stimulation persists. Residual wakefulness, restlessness, and appetite suppression continue. The gap between wanting to redose and actual pleasure widens.
Gradual return toward baseline, though the long elimination half-life means residual stimulation, insomnia, and mild cardiovascular elevation can persist for many hours. Irritability and dysphoria may emerge.
Residual effects may persist for 12–48 hours given the 37-hour serum half-life: lingering insomnia, appetite suppression, fatigue, and low mood.
⚠ Do not drive or operate machinery until after a full night of restorative sleep, which may not be achievable for 24 hours or more after dosing.
Safety[edit]
- Acute toxicity
- Moderate
- Chronic toxicity
- Moderate
- Withdrawal
- Moderate
- Tolerance buildup
- rapid
- Tolerance reset
- —
- Physical
- Low
- Psychological
- High
- Compulsive redosing
- High
- Dose escalation
- High
- Cross-tol.
- cocaine · α-PVP · MDPV
Toxicity
Acute toxicity
No lethal dose has been established for α-PHP. No lethality studies exist, and no published case documents death from α-PHP alone — all documented fatalities involved multiple substances.
Acute toxic presentation includes agitation, hallucinations, paranoid delusions, rapid heart rate, elevated blood pressure, rapid breathing, high body temperature, and muscle breakdown.[7][12][8] Psychosis lasting 3 or more days has been documented, consistent with the compound's long half-life.[8]
Cardiovascular effects
Rapid heart rate, elevated blood pressure, and rapid breathing are consistently reported.[7] Closely related compounds (MDPV, α-PVP) have caused abnormal heart rhythms, dangerously high blood pressure, and heart attacks — these specific outcomes have not been directly reported for α-PHP.inferred
Muscle breakdown
Muscle breakdown (rhabdomyolysis) is documented in α-PHP intoxications.[7] Damaged muscle releases proteins into the bloodstream that can cause acute kidney damage, requiring intravenous fluids and monitoring.
Neurotoxicity
Laboratory studies show α-PHP kills neural stem cells at high concentrations.[19] The concentrations tested were 35 to 2,800 times higher than the maximum measured human blood level; clinical relevance is uncertain.
Genotoxicity
α-PHP itself shows no direct mutation-causing activity, but liver-generated metabolites demonstrated mutagenic potential in laboratory assays.[18]
Reproductive toxicity
A fetal death has been associated with maternal use of α-PHP and MDPHP.[20] The compound crosses to the fetus — two neonates tested positive via meconium.[12]
Psychological Risks
Hallucinations, paranoid ideation, and delusions are the most prominent acute psychological risk. In one documented case, psychosis persisted for 3 days.[8] The 37-hour half-life means episodes last far longer than with shorter-acting stimulants.
Agitation, aggressive behavior, and impaired judgment are consistently reported.[12][7] The combination of paranoia, agitation, and physical drive creates risk of self-harm and violence during acute intoxication.
Tolerance & Dependence
α-PHP has high abuse liability. Preclinical models rate its reward-circuit activation as equivalent to cocaine,[6] and animal studies show reinforcement comparable to cocaine and methamphetamine.[3] The WHO Expert Committee concluded α-PHP is "highly likely to produce a state of dependence similar to amphetamine."[3]
Cross-tolerance with other dopamine reuptake inhibitors — cocaine, MDPV, α-PVP — is expected but has not been directly demonstrated. No controlled human studies on tolerance or dependence formation exist.
Drug Interactions
90% of confirmed cases in the largest clinical series involved multiple substances simultaneously.[12] The most common co-intoxicants were opioids (60%), benzodiazepines (35%), cannabinoids (30%), and cocaine (20%).
Opioids are the most common real-world combination. α-PHP masks opioid sedation; when the stimulant wears off, respiratory depression is unmasked. α-PHP's long half-life changes this danger window compared to cocaine combinations.
Tramadol carries multiple risks: combined norepinephrine reuptake inhibitor raises cardiovascular strain, both drugs independently lower seizure threshold, and tramadol's serotonergic activity creates risk of adrenergic crisis.safety citation needed
MDMA combined with α-PHP produces additive dopamine and norepinephrine activation, substantially elevating cardiovascular stress and overheating risk.safety citation needed
MAO inhibitors are an absolute contraindication: blocking both the breakdown and the reuptake of these neurotransmitters simultaneously creates risk of a dangerous high-blood-pressure crisis.inferred
α-PHP is not detected by standard drug screens,[21] requiring specialized laboratory testing. This complicates emergency treatment, particularly when multiple substances are involved.
Clinical management follows pyrovalerone cathinone protocols: benzodiazepines for agitation and seizure prevention, intravenous fluids for muscle breakdown, and cardiovascular and temperature monitoring.[22]
Contraindications
Pre-existing heart conditions — high blood pressure, coronary artery disease, irregular heartbeat — are the primary absolute contraindication.[7]
Psychotic spectrum disorders and bipolar disorder are absolute contraindications: α-PHP's dopamine potentiation worsens psychotic symptoms, and documented multi-day psychosis[8] makes episodes potentially severe and prolonged.
Pregnancy is absolutely contraindicated: fetal death has been documented,[20] and the compound crosses to the fetus.[12]
MAO inhibitor use is an absolute contraindication.inferred
Seizure disorders are a relative contraindication: stimulant cathinones lower seizure threshold as a class effect.
Concurrent use of other dopamine/norepinephrine-active stimulants — cocaine, amphetamines, MDPV — produces additive cardiovascular and neuropsychiatric risk.
Harm Reduction[edit]
Forms & Identification
α-PHP is not detected by standard immunoassay drug screens,[21] meaning routine workplace or hospital urine tests will not identify it. Confirmatory identification requires specialized laboratory methods.
Synthetic cathinones are frequently mislabeled or substituted on unregulated markets. Reagent testing helps verify identity but cannot confirm purity or dose. Quantitative testing is not available to most users, making precise dosing from unverified material inherently uncertain.
Guidelines
- Test all material with reagent kits before use
- Weigh doses with a milligram-precision scale — never estimate by eye
- Set a firm dose limit before beginning and separate any remaining material from the session space
- Use the oral route for slower onset and reduced compulsive redosing compared to smoking or vaporizing
- Ensure access to water, food, and a cool environment to manage body temperature and hydration
- Schedule the session with at least 24–36 hours of recovery time afterward, including sleep
- Avoid redosing — the long half-life means subsequent doses stack on residual drug, escalating cardiovascular strain and psychosis risk
- Have benzodiazepines available for emergency agitation management if accessible and appropriate
Set & Setting
α-PHP's compulsive redosing drive means having additional material accessible during a session significantly increases the risk of escalating use. Pre-measure a single dose and remove any remaining supply before beginning.
The 37-hour half-life means planning for at least 24 hours of affected function beyond the desired experience. A trusted, sober companion who can recognize paranoid ideation or agitation is a critical safety check — the user may lose insight into their own state.
Aftercare & integration. The primary recovery need after α-PHP use is sleep. The 37-hour half-life means residual stimulation and insomnia may persist for 1–2 days after last use. Do not fight this with additional stimulants.
Eat regular meals even without appetite. Hydrate consistently. Expect a mood crash — dopamine depletion following intense reuptake blockade produces low mood, fatigue, and loss of interest lasting several days.
Physical activity, social contact, and routine help restore baseline faster than isolation. If paranoid thoughts, hallucinations, or severe anxiety persist beyond 72 hours after last use, seek medical evaluation — prolonged psychosis is documented with this compound and may require clinical intervention.
Recovery & Support
α-PHP's high abuse liability and compulsive redosing pattern mean repeated use can rapidly escalate to dependence. The dopaminergic mechanism produces cravings and reward-seeking behavior similar to cocaine and methamphetamine dependence.
Professional support includes addiction medicine specialists, cognitive behavioral therapy, and peer support groups experienced with stimulant dependence. No treatment specific to synthetic cathinone dependence exists, but approaches effective for cocaine and amphetamine dependence apply. Crisis resources include SAMHSA's National Helpline (1-800-662-4357) and local poison control centers.
Recovery resources, crisis lines, and support pathways → View all
Emergency Response
Recognizing an emergency: Seek immediate help for chest pain, seizure, loss of consciousness, body temperature hot to the touch through clothing, sustained aggressive or incoherent behavior, or psychosis with self-harm risk. Severe agitation with inability to sit still, rapid breathing, and confusion indicate serious toxicity.
Immediate steps:
- Call emergency services immediately
- Move the person to a cool, quiet environment
- Remove objects that could cause injury if agitation is present
- Do not physically restrain unless there is immediate danger to self or others
- Offer water if the person can drink safely
- Monitor breathing and consciousness until help arrives
What to tell the dispatcher: Name the substance (α-PHP or synthetic cathinone), estimated amount and time of use, current symptoms, and whether other substances were taken. Good Samaritan laws in many jurisdictions protect callers from prosecution — calling for help is always the right decision.
Clinical management follows pyrovalerone cathinone protocols: benzodiazepines for agitation and seizure prevention, intravenous fluids for muscle breakdown, and cardiovascular and temperature monitoring.[22]
Legal Status[edit]
α-PHP is internationally controlled under Schedule II of the 1971 UN Convention on Psychotropic Substances, effective 2020, following a WHO Expert Committee recommendation in 2019.[3][13] No jurisdiction recognizes a therapeutic use.
| Jurisdiction | Classification | Key provisions |
|---|---|---|
| International (UN) | Schedule II, 1971 Convention on Psychotropic Substances | Effective 2020; recommended by 42nd ECDD meeting 2019[3] |
| United States | Schedule I (Controlled Substances Act) | Temporary placement July 18, 2019 (84 FR 34291); permanent placement July 16, 2021[5] |
| United Kingdom | Class B (Misuse of Drugs Act 1971) | Controlled under generic cathinone clausecitation needed |
| Sweden | Narcotic | Classified June 1, 2015; among earliest national scheduling actions[4] |
| Japan | Controlled | First detected on market 2014; controlled under Narcotics and Psychotropics Control Law[4] |
| EU member states | Subject to 1971 Convention obligations | Monitored by EMCDDA Early Warning System; national implementations vary |
| Canada | Controlled (presumed) | Cathinones broadly addressed under CDSA; specific schedule designation not confirmedcitation needed |
| Australia | Controlled (presumed) | Addressed under state/territory NPS legislation and TGA Poisons Standard; specific schedule not confirmedcitation needed |
Analog act considerations
α-PHP's structural relationship to α-PVP and pyrovalerone — both independently scheduled — means it would likely fall under structural analog legislation in jurisdictions employing structural similarity provisions. In the United States, permanent Schedule I placement renders the Federal Analogue Act moot for α-PHP itself, though it remains relevant for novel analogs not yet individually scheduled.
Legal status changes frequently and varies by jurisdiction. This article does not constitute legal advice. Verify current status through official sources before acting on this information.
references
- [1] ^abcKolaczynska KE, Thomann J, Hoener MC, Liechti ME (2021) The Pharmacological Profile of Second Generation Pyrovalerone Cathinones and Related Cathinone Derivative. — International journal of molecular sciences doi:10.3390/ijms22158277
- [2] ^abcdSimmler LD, Buser TA, Donzelli M, et al. (2012) Pharmacological characterization of designer cathinones in vitro — British Journal of Pharmacology doi:10.1111/j.1476-5381.2012.02145.x
- [3]
- [4] ^abcdDinis P, Franco J, Margalho C (2024) α-Pyrrolidinohexanophenone (α-PHP) and α-Pyrrolidinoisohexanophenone (α-PiHP): A Review — Life doi:10.3390/life14040429
- [5]
- [6] ^abcBaird TR, Davies RA, Glennon RA, Peace MR, Negus SS (2021) A Strategy to Prioritize Emerging Drugs of Abuse for Analysis: Abuse Liability Testing Using Intracranial Self-Stimulation (ICSS) in Rats and Validation with α-Pyrrolidinohexanophenone (α-PHP) — Emerging Trends in Drugs, Addictions, and Health doi:10.1016/j.etdah.2021.100004