MDPHP

3,4-Methylenedioxy-α-pyrrolidinohexanophenone (MDPHP) is a synthetic cathinone in the pyrrolidinophenone group. It is structurally related to MDPV, but has a longer alpha-carbon side chain. MDPHP acts mainly as a dopamine and norepinephrine reuptake inhibitor and has been detected in numerous clinical and forensic investigations. Reported intoxications include severe agitation, delirium, hallucinations, cardiovascular symptoms and loss of consciousness.

Chemistry and history

MDPHP contains a methylenedioxy-substituted phenyl ring, a ketone group and a pyrrolidine ring attached to the alpha carbon. Its side chain is longer than that of MDPV, which has a shorter valerophenone structure. MDPHP appeared on European drug markets in the 2010s and has since been identified in powders, crystals and mixed drug products.

It is important to distinguish MDPHP from MDPiHP. The two are structural isomers with different side-chain branching, and some analytical methods may not separate them adequately.

Pharmacology

MDPHP inhibits dopamine and norepinephrine uptake, with substantially weaker activity at the serotonin transporter. A UK review of synthetic cathinones summarised transporter values of approximately 50 nM at DAT, 60 nM at NET and 9,000 nM at SERT. This profile is consistent with strong dopaminergic and adrenergic stimulation rather than a prominent empathogenic effect (ACMD, 2025).

A 2024 study compared MDPHP with MDPV in mice and reviewed clinical data collected by an Italian poison control centre. Both compounds increased locomotor activity and aggressive behaviour in the animal experiments; at higher exposures they also increased heart rate and blood pressure. The clinical records described severe stimulant toxidromes in people, although many cases involved additional substances (Bassi and colleagues, 2024).

Reported effects

The PsychonautWiki profile of MDPHP and user reports describe stimulation, euphoria and increased alertness. Other reports mention anxiety, restlessness, insomnia and a tendency towards repeated use. These anecdotes cannot predict how intoxication will develop.

Physical effects

Clinical reports include tachycardia, hypertension, chest pain, elevated body temperature, breathing difficulties and rhabdomyolysis. Some patients have presented with delayed physical responses, loss of consciousness or coma. The severity of symptoms varies, and many reported cases also involve opioids, benzodiazepines or other stimulants.

Cognitive and behavioural effects

Agitation, aggressive behaviour, delirium, paranoia and hallucinations have been documented in clinical reports. Some patients show marked psychomotor disturbance, while others present with reduced responsiveness or altered consciousness. These findings reflect the clinical case literature rather than a controlled account of subjective effects.

Clinical and forensic findings

A 2020 study described nine intoxication cases associated with MDPHP and identified seven phase I metabolites and three glucuronide conjugates in authentic human urine. The patients showed varied symptoms, including aggressive behaviour, delayed responses, loss of consciousness and coma. All cases also involved other psychoactive substances, so the contribution of MDPHP could not be isolated (Grapp and colleagues, 2020).

A 2024 clinical series reported 17 acute MDPHP intoxications and described dystonia, psychomotor agitation, delirium and sensory-perception changes. The authors also documented cardiovascular and other systemic symptoms (Arillotta and colleagues, 2024).

Metabolism and toxicity

Human metabolism involves several pathways, including hydroxylation, reduction of the ketone group, N-dealkylation and conjugation. The 2020 study identified seven phase I metabolites and three glucuronides in urine. These markers can assist forensic laboratories in confirming exposure.

MDPHP has been associated with serious and sometimes fatal intoxications, but many cases involve polydrug exposure. The available evidence does not establish a single concentration threshold that predicts toxicity, and the long-term consequences of repeated exposure remain uncertain.

Related compounds

MDPHP is related to MDPV, MDPiHP, α-PHP and α-PiHP. It is a methylenedioxy-substituted pyrrolidinophenone with a longer side chain than MDPV.