α-PHP

Opioids: The paradoxical pairing of stimulants and opioids was the most common polydrug pattern in the Grapp series (60% opioid co-use)supported

60% opiates co-use. bkac057

The clinical toxidrome of α-PHP is consistent with sympathomimetic excess: psychomotor agitation, tremors and fasciculations, tachycardia, tachypnoea, hypertension, hyperthermia, diaphoresis, and in severe cases rhabdomyolysissupported

Clinical cases show CNS toxidromes (psychomotor agitation, tremors, hallucinations), cardiovascular signs (tachycardia), hyperthermia, rhabdomyolysis. j.drugalcdep.2025.112596

The 29-case forensic series reported serum concentrations of 1–83 ng/mL (mean 40, median 36 ng/mL), but the near-universal polydrug context (opioids 60%, benzodiazepines 35%, cannabinoids 30%, cocaine 20%) prevents attribution of specific toxicity thresholds to α-PHP alone.supported

Serum concentrations 1–83 ng/mL (mean 40, median 36 ng/mL)... 60% opiates co-use. bkac057

The mechanism involves both direct sympathomimetic thermogenesis and agitation-driven muscular heat production; when combined with environmental factors (enclosed spaces, physical exertion) or co-administration of other serotonergic or stimulant drugs, life-threatening core temperature elevation can develop rapidly.supported

Sympathomimetic and hallucinogenic toxidromes, excited/agitated delirium syndrome, serotonin syndrome risk. ijms24076230

A single case report documented fetal death associated with maternal use of both MDPHP and α-PHPsupported

Case report of fetal death associated with 3,4-MDPHP and α-PHP use. 15563650.2018.1502443

Claim in safety — inconclusiveinconclusiveworking →

Lenzi et al. assessed α-PHP mutagenicity in TK6 human lymphoblastoid cellssupported

α-PHP and α-PVP not mutagenic in parent form on TK6 cells but metabolites show mutagenicity with extrinsic metabolic activation. ijms22126320

Synthetic cathinones as a class produce neurological adverse effects including encephalopathy, coma, convulsions, seizure threshold reduction, serotonin syndrome (primarily for serotonergic cathinones), and excited/agitated delirium syndrome. α-PHP's minimal SERT activity reduces its serotonin syndrome risk relative to serotonergic cathinones, but the dopaminergic-noradrenergic toxidrome — including seizure threshold reduction and excited delirium — applies based on mechanism. No direct neurotoxicity studies (dopaminergic terminal damage, oxidative stress markers, apoptosis assays) have been published for α-PHP.supported

Brain-related adverse effects include encephalopathy, coma, convulsions. Sympathomimetic and hallucinogenic toxidromes, excited/agitated delirium syndrome, serotonin syndrome risk. ijms24076230

Claim in safety — inconclusiveinconclusiveworking →

Psychomotor agitation and aggression were documented in the Grapp forensic series and Pavia Poison Control Centre datasupported

Clinical cases show CNS toxidromes (psychomotor agitation, tremors, hallucinations). j.drugalcdep.2025.112596

Claim in safety — inconclusiveinconclusiveworking →

Hallucinations and paranoia — both visual and auditory hallucinations, along with paranoid ideation and disorientation, are reported in clinical casessupported

Clinical cases show CNS toxidromes (psychomotor agitation, tremors, hallucinations). j.drugalcdep.2025.112596

This syndrome — characterized by extreme agitation, altered consciousness, hyperthermia, and risk of sudden death — is documented across the cathinone class and is particularly associated with high-dose or prolonged stimulant binges.supported

excited/agitated delirium syndrome, serotonin syndrome risk. ijms24076230

DAT/NET blockade combined with impaired monoamine catabolism results in dangerous catecholamine accumulation in the synaptic cleftsupported

Sympathomimetic and hallucinogenic toxidromes, excited/agitated delirium syndrome. ijms24076230

Compulsive redosing is a behavioral pattern strongly predicted by the pharmacological profile: potent DAT inhibition with slow receptor dissociation drives sustained activation of incentive salience ("wanting") circuitry in the mesolimbic pathwaysupported

S-enantiomers of pyrovalerone analogs show slow koff from DAT, predicting more persistent in vivo effects vs cocaine and methylphenidate. pnas.2114204120

Compulsive redosing is a behavioral pattern strongly predicted by the pharmacological profile: potent DAT inhibition with slow receptor dissociation drives sustained activation of incentive salience ("wanting") circuitry in the mesolimbic pathwaysupported

Covers abuse potential, preclinical models, illicit market trends, harm reduction strategies. brainsci14040334

Psychiatric effects of synthetic cathinones reviewed systematically include anxiety, depression, and psychotic symptoms persisting beyond acute intoxication in some casessupported

109 NPS intoxication cases with acute or chronic psychiatric symptoms. Most common: hallucinations, aggressiveness, psychotic behavior. Synthetic cathinones second most common NPS class involved. ijms25179484

Abuse liability: Animal ICSS data provide the strongest available signal. α-PHP decreases brain reward thresholds at doses of 5–10 mg/kg in female rats, with a magnitude equivalent to α-PVP and comparable to methamphetamine (~19–20% threshold reduction)partially supported

Brain reward thresholds decreased (ICSS). Abuse liability assessed as equivalent for all three compounds. j.drugalcdep.2021.108910

Abuse liability: Animal ICSS data provide the strongest available signal. α-PHP decreases brain reward thresholds at doses of 5–10 mg/kg in female rats, with a magnitude equivalent to α-PVP and comparable to methamphetamine (~19–20% threshold reduction)supported

α-PVP and 4-methyl-N-ethcathinone produce ICSS threshold reductions similar to methamphetamine. Suggests pyrovalerone cathinones activate brain reward circuitry with abuse potential comparable to methamphetamine. pyu014

The slow DAT dissociation kinetics of pyrovalerone S-enantiomers may produce more sustained reward signaling than cocaine or methylphenidate at equivalent doses, potentially elevating addiction risk beyond what IC₅₀-based comparisons would suggest.supported

S-enantiomers of pyrovalerone analogs show slow koff from DAT, predicting more persistent in vivo effects vs cocaine and methylphenidate. In vitro drug-binding kinetics correlate with time-course of in vivo psychostimulant action. pnas.2114204120

Claim in safety — inconclusiveinconclusiveworking →

Compulsive use patterns: The combination of potent DAT inhibition and slow receptor dissociation is expected to promote compulsive redosingsupported

Reviews neurotoxic properties of synthetic cathinones including neuroinflammation, neurotransmitter dysregulation, monoamine transporter alterations. Covers abuse potential, preclinical models. brainsci14040334

Claim in safety — inconclusiveinconclusiveworking →

Claim in safety — inconclusiveinconclusiveworking →

Serotonergic agents: α-PHP itself shows minimal SERT activity, but serotonin syndrome has been reported across the cathinone class, potentially via indirect noradrenergic-serotonergic cross-signaling or through co-ingested serotonergic substancessupported

SAR study of 4-substituted α-PHP analogues showed 28- to >300-fold selectivity for DAT over SERT. acschemneuro.3c00156

Serotonergic agents: α-PHP itself shows minimal SERT activity, but serotonin syndrome has been reported across the cathinone class, potentially via indirect noradrenergic-serotonergic cross-signaling or through co-ingested serotonergic substancessupported

serotonin syndrome risk. ijms24076230

Lithium: Theoretical concern — lithium may lower seizure threshold, and combination with a stimulant that independently reduces seizure threshold could produce additive risksupported

Brain-related adverse effects include encephalopathy, coma, convulsions. ijms24076230

Concurrent MAOI use: Risk of fatal hypertensive crisis and catecholamine storm.supported

Sympathomimetic and hallucinogenic toxidromes. ijms24076230

Pregnancy: A case report documents fetal death associated with α-PHP exposure (polydrug context); neonatal exposure confirmed via meconium. Potent sympathomimetic stimulation poses intrinsic risk to fetal hemodynamics regardless of whether α-PHP is the sole causative agent.supported

Case report of fetal death associated with 3,4-MDPHP and α-PHP use. First case linking these synthetic cathinones to fetal mortality. 15563650.2018.1502443

Claim in safety — inconclusiveinconclusiveworking →

Severe cardiovascular disease: Pre-existing conditions including uncontrolled hypertension, coronary artery disease, heart failure, and arrhythmias represent absolute contraindications given the documented tachycardia, hypertension, and thoracic pain in clinical cases.supported

cardiovascular signs (tachycardia) j.drugalcdep.2025.112596

Seizure disorders: Synthetic cathinones as a class reduce seizure threshold. Individuals with epilepsy or other seizure predisposition face elevated risk.supported

Brain-related adverse effects include encephalopathy, coma, convulsions. ijms24076230

Claim in safety — inconclusiveinconclusiveworking →

Hepatic impairment: α-PHP undergoes extensive hepatic metabolism. Impaired liver function could alter metabolite profiles and exposure levels unpredictably.supported

19 Phase I + 9 Phase II metabolites life14040429

It functions exclusively as a transporter blocker — it does not induce monoamine efflux (i.e., it is not a releaser)supported

No monoamine efflux. ijms22158277

In synaptosomal reuptake assays, α-PHP is at least as potent as α-PVP at inhibiting DAT-mediated dopamine reuptakesupported

α-PHP at least as potent as α-PVP as a DAT reuptake inhibitor. acschemneuro.3c00156

A systematic SAR study of 4-substituted α-PHP analogues demonstrated that essentially all tested compounds behaved as 28- to >300-fold selective DAT versus SERT reuptake inhibitors, confirming the strong dopaminergic selectivity of the α-PHP scaffoldsupported

SAR study of 4-substituted α-PHP analogues showed 28- to >300-fold selectivity for DAT over SERT. The 4-CF3 analogue was an outlier (~80-fold less potent). acschemneuro.3c00156

Claim in pharmacology — inconclusiveinconclusiveworking →

Claim in pharmacology — inconclusiveinconclusiveworking →

Extension of the α-alkyl chain — the precise structural modification differentiating α-PVP (pentyl) from α-PHP (hexyl) — enhances both DAT and NET inhibition potency within the pyrovalerone series.supported

Alkyl chain extension enhances NET and DAT inhibition. ijms22158277

The S-enantiomers of pyrovalerone, α-PVP, and MDPV exhibit slow dissociation (low k_off) from DAT, and this kinetic property directly predicts the more persistent psychostimulant effects observed in vivo relative to cocaine and methylphenidatesupported

S-enantiomers of pyrovalerone analogs show slow koff from DAT, predicting more persistent in vivo effects vs cocaine and methylphenidate. In vitro drug-binding kinetics correlate with time-course of in vivo psychostimulant action. Studied pyrovalerone, α-PVP, and MDPV enantiomers. pnas.2114204120

Claim in pharmacology — inconclusiveinconclusiveworking →

Elimination half-life: A value of approximately 37 hours has been cited in review literature, with a corresponding total elimination time of approximately 150 hourssupported

half-life 37h life14040429

This figure likely derives from community pharmacokinetic estimates rather than a controlled study; no peer-reviewed primary pharmacokinetic study measuring α-PHP half-life in humans has been published. For comparison, the closely related α-PVP has a half-life estimated from a single non-fatal intoxication case, but this also represents a case-level observation rather than formal PK characterization.supported

Pharmacokinetic case report for α-PVP (α-PHP direct homolog) measuring elimination half-life in vivo. 15563650.2016.1166509

Across all published studies, 19 Phase I and 9 Phase II metabolites have been identifiedsupported

19 Phase I + 9 Phase II metabolites life14040429

In a 29-case forensic series, 11 Phase I metabolites and 5 Phase II glucuronide conjugates were confirmed in human urine, with dihydroxy-pyrrolidinyl-α-PHP and dihydro-α-PHP as the most abundant urinary markers and 2'-oxo-dihydro-α-PHP and 2'-oxo-α-PHP as secondary markerssupported

11 phase I + 5 phase II glucuronide metabolites identified in human urine. Main markers: dihydroxy-pyrrolidinyl-α-PHP and dihydro-α-PHP. bkac057

Human hepatocyte incubation studies independently identified α-PHP dihydroxy-pyrrolidinyl as a novel major metabolite not previously detected in urine analyses.supported

α-PHP dihydroxy-pyrrolidinyl identified as novel major metabolite. ijms22010230

Claim in pharmacology — inconclusiveinconclusiveworking →

Claim in pharmacology — inconclusiveinconclusiveworking →

Claim in pharmacology — inconclusiveinconclusiveworking →

α-PVP has a case-level pharmacokinetic half-life estimate from a non-fatal intoxication; no equivalent primary PK data exist for α-PHP.supported

Pharmacokinetic case report for α-PVP (α-PHP direct homolog) measuring elimination half-life in vivo. 15563650.2016.1166509

MDPHP appeared in European clinical and seizure data from approximately 2017 and has been implicated in fatal polydrug intoxicationspartially supported

9 cases of MDPHP (3,4-methylenedioxy-α-PHP) intoxication 2019. Serum 3.3–140 ng/mL... Polydrug presentations with opiates/benzodiazepines. dta.2869

MDPHP appeared in European clinical and seizure data from approximately 2017 and has been implicated in fatal polydrug intoxicationssupported

Fatal intoxication with MDPHP... Cause of death: acute multidrug intoxication. bkaf048

Chain extension from pentyl (α-PVP) to hexyl (α-PHP) enhances DAT and NET inhibition potencysupported

Alkyl chain extension enhances NET and DAT inhibition. ijms22158277

Chain extension from pentyl (α-PVP) to hexyl (α-PHP) enhances DAT and NET inhibition potencysupported

α-PHP at least as potent as α-PVP as a DAT reuptake inhibitor. acschemneuro.3c00156

The 4-CF₃ analogue of α-PHP is a notable outlier — approximately 80-fold less potent at DAT with reduced DAT/SERT selectivity — demonstrating that ring substitution, unlike chain extension, can substantially disrupt the pyrovalerone SAR.supported

The 4-CF3 analogue was an outlier (~80-fold less potent). acschemneuro.3c00156

Taffe et al. confirmed equivalent locomotor stimulation and abuse liability between α-PHP and α-PVP in female rats.supported

Abuse liability assessed as equivalent for all three compounds. j.drugalcdep.2021.108910

First, the pyrovalerone class exhibits slow dissociation from DAT (low k_off), whereas cocaine and methylphenidate dissociate rapidly — a difference that predicts more sustained psychostimulant effects for α-PHP at equivalent receptor occupancysupported

S-enantiomers of pyrovalerone analogs show slow koff from DAT, predicting more persistent in vivo effects vs cocaine and methylphenidate. pnas.2114204120

The compound is the one-carbon α-alkyl chain homolog of α-PVP, carrying a hexyl rather than pentyl side chain, and produces intense but relatively brief stimulation via inhalation (peak 30–90 minutes) with substantially longer effects orally (peak 4–6 hours).supported

Dedicated review of α-PHP and α-PiHP... dose tables, duration tables. life14040429

Patented in 1967 as part of a series of α-pyrrolidine ketones, α-PHP was never clinically developed and emerged on illicit markets in Japan in 2014 as a novel psychoactive substance following regulatory pressure on α-PVPsupported

α-PHP developed in 1960s; US patent April 1967, expired 1984. Appeared on Japanese drug market 2014. life14040429

α-PHP blocks reuptake at the dopamine transporter (DAT) with potency at least equivalent to α-PVP and exhibits 28- to >300-fold selectivity for DAT over the serotonin transporter (SERT)supported

α-PHP at least as potent as α-PVP as a DAT reuptake inhibitor. SAR study of 4-substituted α-PHP analogues showed 28- to >300-fold selectivity for DAT over SERT. acschemneuro.3c00156

It functions exclusively as a transporter blocker — not a monoamine releasersupported

No monoamine efflux. ijms22158277

The pyrovalerone class to which α-PHP belongs is characterized by slow dissociation (low k_off) of S-enantiomers from DAT, a kinetic property that produces more sustained psychostimulant effects than cocaine or methylphenidate.supported

S-enantiomers of pyrovalerone analogs show slow koff from DAT, predicting more persistent in vivo effects vs cocaine and methylphenidate. pnas.2114204120

Claim in summary — inconclusiveinconclusiveworking →

Animal intracranial self-stimulation data indicate abuse liability equivalent to α-PVP and comparable to methamphetamine-class compoundspartially supported

Brain reward thresholds decreased (ICSS). Abuse liability assessed as equivalent for all three compounds. j.drugalcdep.2021.108910

A single case report links α-PHP (with co-administered MDPHP) to fetal deathsupported

Case report of fetal death associated with 3,4-MDPHP and α-PHP use. 15563650.2018.1502443

Intracranial self-stimulation (ICSS) studies offer direct measurement of brain reward circuit activation. α-PHP dose-dependently decreased ICSS thresholds in female rats at 5 and 10 mg/kg, indicating facilitation of brain rewardsupported

Suppressed wheel activity at 5 and 10 mg/kg. Brain reward thresholds decreased (ICSS). j.drugalcdep.2021.108910

The slow dissociation kinetics (low k_off) demonstrated for S-enantiomers of the pyrovalerone class at DAT have a direct neural consequence: sustained elevation of synaptic dopamine in the NAc beyond what equilibrium affinity alone would predictsupported

S-enantiomers of pyrovalerone analogs show slow koff from DAT, predicting more persistent in vivo effects vs cocaine and methylphenidate. pnas.2114204120

Niello et al. showed that k_off — not IC₅₀ — is the kinetic parameter that best predicts in vivo psychostimulant duration and behavioral potency across the cocaine-methylphenidate-pyrovalerone spectrumsupported

In vitro drug-binding kinetics correlate with time-course of in vivo psychostimulant action. pnas.2114204120

The slow-off DAT kinetics of the pyrovalerone class may amplify the dissociation between wanting and liking — driving compulsive redosing even as subjective euphoria diminishes with repeated dosingsupported

S-enantiomers of pyrovalerone analogs show slow koff from DAT, predicting more persistent in vivo effects vs cocaine and methylphenidate. pnas.2114204120

This framework aligns with the high compulsive use potential inferred from both animal and clinical data.supported

Covers abuse potential, preclinical models, illicit market trends, harm reduction strategies. brainsci14040334

Does α-PHP produce the same enantioselective slow-off DAT kinetics as α-PVP and MDPV? The structural continuity of the series suggests it should, but direct measurement of α-PHP enantiomer k_off values at DAT is required to confirm.supported

Studied pyrovalerone, α-PVP, and MDPV enantiomers. pnas.2114204120

α-PHP belongs to a series of α-pyrrolidine ketones first described in a United States patent issued in April 1967supported

US patent April 1967, expired 1984. life14040429

α-PHP first appeared on the illicit drug market in Japan in 2014, entering circulation as a novel psychoactive substance (NPS) in the wake of regulatory action against its direct structural predecessor, α-PVP (commonly known as "flakka"). α-PVP had attracted intense law enforcement and media attention following a series of high-profile public intoxication incidents in the United States. α-PHP differs from α-PVP by a single methylene unit — a hexyl rather than pentyl α-alkyl side chain — a minimal modification that preserved pharmacological activity while initially circumventing scheduling controls targeting α-PVP specifically.supported

Appeared on Japanese drug market 2014. life14040429

α-PHP first appeared on the illicit drug market in Japan in 2014, entering circulation as a novel psychoactive substance (NPS) in the wake of regulatory action against its direct structural predecessor, α-PVP (commonly known as "flakka"). α-PVP had attracted intense law enforcement and media attention following a series of high-profile public intoxication incidents in the United States. α-PHP differs from α-PVP by a single methylene unit — a hexyl rather than pentyl α-alkyl side chain — a minimal modification that preserved pharmacological activity while initially circumventing scheduling controls targeting α-PVP specifically.supported

α-PHP is the one-carbon α-extended homolog of α-PVP; both are U.S. Schedule I controlled substances. acschemneuro.3c00156

The closely related methylenedioxy analogue, MDPHP (3,4-methylenedioxy-α-PHP), appeared in European drug seizure data and clinical case reports from approximately 2017 onward, extending the same evasion logic to a 3,4-ring-substituted scaffold.partially supported

9 cases of MDPHP (3,4-methylenedioxy-α-PHP) intoxication 2019. dta.2869

Claim in history — inconclusiveinconclusiveworking →

Bassi et al. reported sex-dependent pharmacokinetic differences in CD-1 mice administered α-PHP (0.1–30 mg/kg i.p.)supported

Evaluates acute effects of α-PHP (0.1–30 mg/kg i.p.) in CD-1 male and female mice. Sex differences found — female mice more sensitive. Male mice show higher plasma levels. j.drugalcdep.2025.112596

Forensic urine analysis (n = 29): Grapp et al. identified 11 Phase I and 5 Phase II (glucuronide) metabolites in confirmed α-PHP user urine specimenssupported

29-case series with confirmed α-PHP intake... 11 phase I + 5 phase II glucuronide metabolites identified in human urine. bkac057

Human hepatocyte incubation: Carlier et al. identified α-PHP dihydroxy-pyrrolidinyl as a novel major metabolite not previously observed in urine-based studies, demonstrating that in vitro hepatocyte models capture biotransformation pathways that may be underrepresented in urinary excretion profiles.supported

α-PHP dihydroxy-pyrrolidinyl identified as novel major metabolite. ijms22010230

Claim in pharmacokinetic-detail — inconclusiveinconclusiveworking →

Claim in pharmacokinetic-detail — inconclusiveinconclusiveworking →

Bassi et al. characterized dose-response relationships for α-PHP (0.1–30 mg/kg i.p.) in male and female CD-1 micesupported

Evaluates acute effects of α-PHP (0.1–30 mg/kg i.p.) in CD-1 male and female mice. j.drugalcdep.2025.112596

The largest published case series is the Grapp et al. 29-case series of forensic and clinical toxicology cases involving confirmed α-PHP exposuresupported

29-case series with confirmed α-PHP intake. bkac057

Claim in clinical-evidence — inconclusiveinconclusiveworking →

A single case report documented fetal death associated with maternal use of both 3,4-MDPHP and α-PHPsupported

Case report of fetal death associated with 3,4-MDPHP and α-PHP use. First case linking these synthetic cathinones to fetal mortality. 15563650.2018.1502443

The compound does not promote monoamine efflux — it is mechanistically a pure uptake blocker, not a substrate-type releaser.supported

No monoamine efflux. ijms22158277

Quantitative binding data for the pyrovalerone cathinone series at human monoamine transporters (HEK293 expression system):supported

Pyrovalerone cathinones profiled at human NET, DAT, SERT. ijms22158277

Claim in receptor-pharmacology — inconclusiveinconclusiveworking →

Extension of the α-alkyl chain from pentyl (α-PVP) to hexyl (α-PHP) enhanced both DAT and NET inhibition potency, establishing chain length as a primary determinant of transporter affinity in this series.supported

Alkyl chain extension enhances NET and DAT inhibition. ijms22158277

This progressive chain elongation within the pyrovalerone series has been systematically investigated for its effects on monoamine transporter inhibition potency and selectivity.supported

α-PHP is the one-carbon α-extended homolog of α-PVP... SAR study of 4-substituted α-PHP analogues showed 28- to >300-fold selectivity for DAT over SERT. acschemneuro.3c00156

Enantioselective pharmacology has not been directly characterized for α-PHP; however, within the structurally related pyrovalerone series, the S-enantiomers of pyrovalerone, α-PVP, and MDPV demonstrate markedly slower dissociation (k_off) from DAT than R-enantiomers — a kinetic property that directly predicts prolonged in vivo psychostimulant effectssupported

S-enantiomers of pyrovalerone analogs show slow koff from DAT, predicting more persistent in vivo effects vs cocaine and methylphenidate. Studied pyrovalerone, α-PVP, and MDPV enantiomers. pnas.2114204120

Inhalation and intravenous use produce a rapid, intense onset dominated by euphoric rush and compulsive redosing urge — the slow dissociation of the pyrovalerone class from DAT sustains reward-circuit activation beyond what the brief peak duration might suggestsupported

S-enantiomers of pyrovalerone analogs show slow koff from DAT, predicting more persistent in vivo effects vs cocaine and methylphenidate. pnas.2114204120

Relative to α-PVP, α-PHP is reported to produce comparable stimulation intensity and compulsive redosing potential, consistent with their near-identical pharmacological profiles and equivalent ICSS threshold reductions in animal modelssupported

Abuse liability assessed as equivalent for all three compounds. Inhalation route produces abbreviated duration vs injection. j.drugalcdep.2021.108910

α-PHP is internationally controlled under Schedule II of the 1971 United Nations Convention on Psychotropic Substances, following the WHO Expert Committee on Drug Dependence critical review in December 2019 and formal placement in December 2020supported

Schedule II international control December 2020. life14040429