4-FPP was first identified as a urinary metabolite of the sedative niaprazine in 1982 and subsequently sold (2003-2008) in New Zealand "party pills" together with BZP under brand names including "The Big Grin," "Mashed," and "Extreme Beans." In vitro, it is a high-efficacy 5-HT1A agonist (Ki ≈ 11 nM), moderate 5-HT2A/2C partial agonist, and weak SERT/NET releaser. DAT activity is negligible, explaining its low stimulant euphoria compared to BZP. Subjectively, it produces light empathic warmth, mild color enhancement/tracers, and prominent vasoconstrictive "head pressure." Nausea, migraine-like headaches, myalgia, and anxiety are common above ~100 mg. Unlike BZP, 4-FPP inhibits several hepatic CYPs (notably 1A2, 2D6, 3A4), which can prolong co-administered drugs. Rodent LD50 (oral) ≈ 400 mg/kg; no confirmed fatalities as sole agent, but severe hyperthermia, seizures, and rhabdomyolysis have been reported in polydrug cases.
Also known as: Pfpp, Fluoperazine, Flipiperazine, Para-fluorophenylpiperazine
Classification
Chemical: Piperazine
Psychoactive: Entactogen
Psychoactive: Psychedelic
Psychoactive: Stimulant
Tag: Empathogen
Tag: Phenylpiperazine
Tag: Research-Chemical
Tag: Tentative
Effects
Brightness Alteration
Pupil Dilation
Vasoconstriction
Muscle Tension
Teeth Grinding
Nausea
Empathy Enhancement
Euphoria
Anxiety
Emotional Warmth
Anxiety Suppression
Thought Loop
Color Enhancement
Tracers
Closedeye Visuals
Open Eye Visuals
Patterning
Increased Music Appreciation
Routes of Administration
Oral
Dosage
Threshold: 10-15 mg
Light: 20-40 mg
Common: 40-80 mg
Strong: 80-150 mg
Heavy: 150 mg
Duration
Onset: 0.25-0.75 h
Comeup: 0.5-1 h
Peak: 1-3 h
Offset: 1-2 h
After Effects: 2-12 h
Total Duration: 4-8 h
Insufflated
Dosage
Threshold: 5–10 mg
Light: 10-20 mg
Common: 20-35 mg
Strong: 35-50 mg
Heavy: 70+ mg
Duration
Onset: 0.083-0.25 h
Comeup: 0.25-0.5 h
Peak: 0.5-2 h
Offset: 1-2 h
After Effects: 2-12 h
Total Duration: 3-6 h
Rectal
Dosage
Threshold: 10 mg
Light: 15-30 mg
Common: 30-60 mg
Strong: 60-90 mg
Heavy: >90 mg
Duration
Onset: 0.17-0.33 h
Comeup: 0.33-0.67 h
Peak: 1-2.5 h
Offset: 2.5-5 h
After Effects: 2-12 h
Total Duration: 4-7 h
Harm Reduction
Check interactions before mixing substances, pay attention to dose spacing and hydration, and treat all dosage guidance as approximate rather than guaranteed safe.
Sources
Substance data is aggregated from the following public harm-reduction and reference sources.
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4-FPP - DrugsPRO gwida tal-sustanza
4-FPP: 4-FPP was first identified as a urinary metabolite of the sedative niaprazine in 1982 and subsequently sold (2003-2008) in New Zealand "party pills" together with BZP under brand names including "The Big Grin," "Mashed," and "Extreme Beans." In vitro, it is a high-efficacy 5-HT1A agonist (Ki
