HDMP-28 (Ethylnaphthidate)
HDMP-28, also called ethylnaphthidate, is a naphthyl analogue of methylphenidate first studied as a potent dopamine reuptake inhibitor in the 1990s and later appearing on research-chemical markets. It is markedly more potent than methylphenidate at the dopamine transporter in preclinical work, with essentially no human safety data.
01 Overview
HDMP-28 replaces the phenyl ring of methylphenidate with a naphthyl group, producing a highly potent dopamine transporter inhibitor in animal and binding studies. It was investigated academically as a pharmacological tool before appearing as a grey-market stimulant.
No controlled human studies exist. Its high DAT potency raises strong concern for abuse liability and cardiovascular/psychiatric toxicity; user reports describe intense, compulsive stimulation.
02 Mechanism
Potent dopamine (and norepinephrine) reuptake inhibitor; naphthyl substitution greatly increases transporter affinity relative to methylphenidate.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Common (approximate, anecdotal) | 5–15 mg | Oral | Highly potent; user-reported only, no validated data. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Potent stimulationIntense wakefulness, drive and euphoria reported. | Strong | Anecdotal | |
| Compulsive useHigh DAT potency drives strong redosing urges. | Strong | Anecdotal |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Cardiovascular toxicityTachycardia, hypertension and arrhythmia risk expected from potent stimulation. | Severe | Unknown | Unconfirmed | |
| Paranoia and psychosisPotent dopaminergic drive risks paranoia and psychotic symptoms with heavy use. | Severe | Unknown | Unconfirmed |