5F-PB-22
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5F-PB-22 — also known as 5F-QUPIC — is a synthetic cannabinoid of the indole-3-carboxylate class. It is a fluorinated structural analog of PB-22, distinguished by extreme potency at cannabinoid receptors in the brain.[1] It activates those receptors with no natural ceiling on stimulation, producing an intensified, unmoderated version of cannabis intoxication.
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5F-PB-22 appeared on commercial "Spice" markets in 2012–2013 — the first synthetic cannabinoid to combine an ester bond with a quinoline structure.[2] Its novel design briefly evaded existing drug laws, but multiple deaths linked to the herbal product "Psyclone" prompted rapid scheduling.[3] The United States permanently scheduled it in 2016,[4] and it is now internationally controlled, though it continues to circulate in prisons via drug-infused paper.[5]
Subjective effects include euphoria, heavy sedation, perceptual softening, and cognitive slowing. The experience resembles cannabis at its most intense — compressed into a far narrower dose range, with no pharmacological ceiling. Anxiety, paranoia, and acute agitation are characteristic unwanted effects, and the line between an intense experience and a medical emergency can be crossed without warning.
Dependence is possible with regular use,[6] and the compound has been directly linked to multiple deaths.[3] Blood levels in people who died overlap with levels in people who survived — tolerance, co-use of other substances, and individual variation determine whether a given amount proves fatal.[7] No controlled human studies exist; what is known comes from forensic casework, laboratory pharmacology, and animal data.
History[edit]
Discovery and market emergence
PB-22, the non-fluorinated parent compound, first appeared in herbal blend seizures in Japan in 2012–2013. 5F-PB-22 followed quickly onto commercial "Spice" markets — the first synthetic cannabinoid to combine an ester bond with a quinoline structure.[2] The compound appears to have been produced clandestinely to exploit regulatory gaps rather than by academic researchers.
Regulatory response
The United States temporarily placed 5F-PB-22 under Schedule I control in January 2014, alongside three other synthetic cannabinoids.[8] Permanent US scheduling followed in September 2016.[4] The United Kingdom, China, and the UN enacted controls between 2015 and 2018.[9]
Context of use
5F-PB-22 reached users through herbal blends sold online and in head shops, and through synthetic cannabinoid-infused paper circulated in prisons.[5] Its extreme potency — active in low-milligram amounts — made it well-suited for paper substrates, where small pieces carry enough compound for a psychoactive effect. In the United States, forensic identification in 2013 linked it to the herbal product marketed as "Psyclone".[3]
The compound circulates under two names: 5F-PB-22 in Western forensic literature and 5F-QUPIC in Japanese analytical reports. The brand name "Psyclone" became briefly notorious in 2013 when it was linked to multiple fatalities in the United States.[3] Unlike earlier synthetic cannabinoids such as JWH-018, 5F-PB-22 never acquired street slang — its market lifespan was compressed by rapid scheduling.
Chemistry[edit]
Structural class
5F-PB-22 belongs to the indole-3-carboxylate class of synthetic cannabinoids — specifically the quinolinyl ester subgroup. Its structure combines an indole core, an ester bond, and a quinoline ring, with a fluorinated 5-carbon chain at the nitrogen. The ester bond is what sets PB-22-type compounds apart from other synthetic cannabinoid families; it is rapidly broken down by liver enzymes, limiting how long the compound stays active.[10]
Molecular properties
| Molecular formula | C₂₃H₂₁FN₂O₂ |
| Molecular weight | 376.4 g/mol |
The parent compound PB-22 has the same structure but without the terminal fluorine atom. That single fluorine makes the compound highly fat-soluble, allowing it to cross into the brain efficiently.[7] Ten positional isomers exist — structural variants with different quinoline arrangements — not all of which are currently scheduled.[11] The crystal structure has been confirmed by X-ray diffraction.[12]
Pharmacology[edit]
Mechanism of action
5F-PB-22 is a full agonist at cannabinoid receptors — it drives maximum activation with no built-in ceiling, unlike THC in cannabis, which is a partial agonist.[1] Effects intensify with dose until toxicity intervenes. In animal studies, it selectively raised dopamine in the brain's core reward region — a pharmacological marker of abuse liability.[13]
Pharmacokinetics
No human pharmacokinetic data have been published for 5F-PB-22. The compound is highly fat-soluble, which allows it to reach the brain quickly but means the parent compound is nearly undetectable in standard urine drug tests.[7]
Metabolism
The liver breaks down 5F-PB-22 by splitting the ester bond,[10] producing a main breakdown product detectable in urine as the primary forensic marker.[14] When alcohol is present, the liver converts 5F-PB-22 into an ethyl ester instead — a unique byproduct confirmed in postmortem blood that indicates combined alcohol and synthetic cannabinoid use.[15][16]
Neuroscience[edit]
Where it acts
CB1 receptors are concentrated in brain regions governing memory, movement, coordination, and decision-making. 5F-PB-22 floods these receptors, suppressing neurotransmitter release and disrupting the balance between excitation and inhibition that underlies normal cognition and motor control. It also selectively raises dopamine in the brain's reward circuit — the mechanism that drives compulsive drug-seeking.[1]
Why it matters
The endocannabinoid system normally operates through on-demand release of partial activators that fine-tune neural signaling. 5F-PB-22 overrides this with maximum-strength full activation — flooding a system designed for delicate self-regulation. Cannabis contains CBD, which counteracts some of this activation;[17] 5F-PB-22 has no equivalent brake.
In cell cultures, biologically relevant concentrations doubled neuronal growth through a cannabinoid receptor mechanism.[18] This raises concern for exposure during development — particularly in prenatal and early postnatal periods, when endocannabinoid signaling guides how neural circuits are wired.
Postmortem blood levels in fatal cases are extremely low (0.37–1.5 ng/mL). Whether death results from direct receptor-driven toxicity or from secondary effects — such as a fatal heart rhythm disturbance — has not been established. It also remains unknown how much intact compound actually reaches the brain before the ester bond is broken down.
Subjective Effects[edit]
The 5F-PB-22 experience sits in cannabis territory — sedation, euphoria, perceptual softening, and cognitive slowing — but the dose window is dramatically narrower. Full cannabinoid receptor activation with no ceiling and no moderating CBD means that an amount that feels manageable can cross into toxicity without warning.
Relative to JWH-018 and earlier synthetic cannabinoids, the effects are qualitatively similar but arrive at substantially lower doses. Compared to cannabis, the experience lacks any self-limiting quality — the ceiling that tells a cannabis user they have had enough simply is not there.
Effect Grid
Clear cannabis-like intoxication with full CB1 agonist intensity. Euphoria is pronounced, accompanied by sedation and cognitive slowing. Thought deceleration and analysis suppression become obvious. Immersion enhancement may deepen engagement with media or music. Perceptual shifts include color enhancement, music enhancement, and mild vestibular distortion.
Physically, motor control impairment is noticeable — coordination and reaction time are reduced. Bodily heaviness is prominent. Appetite enhancement is reliable. Heart rate elevation (abnormal heartbeat) may become perceptible. Spontaneous body sensations and dehydration sensation are common.
Anxiety and paranoia are possible, especially in naive users, unfamiliar settings, or at the upper end of this range. The compressed margin between desired effects and toxicity makes careful dosing essential.
Modeled from the effect's dose-dependence curve — not per-substance measurements.
Perspective distortion · Proprioceptive distortion · Sound sensitivity · Vestibular distortion · Visual acuity suppression · Visual haze / noise · Taste enhancement · Light sensitivity · Color enhancement · Visual breathing · Visual drifting · Visual processing suppression · Auditory hallucinations · External hallucinations
Visual acuity suppression · Visual haze / noise · Taste enhancement · Light sensitivity · Color enhancement · Visual breathing · Visual drifting · Visual processing suppression · Auditory hallucinations · External hallucinations
Dizziness · Heart rate perception changes · Muscle relaxation · Physical fatigue · Appetite enhancement · Bodily heaviness · Headache · Laughter fits · Nausea · Pain suppression · Restlessness · Spontaneous body sensations · Tactile euphoria · Bodily pressures · Body schema distortion · Constipation · Excessive sweating · Nausea suppression · Tingling / electric sensations · Trembling · Vibrations / buzzing · Vomiting · Breathing alteration · Pupil dilation · Involuntary body movements · Nystagmus (eye wobbles) · Stimulation · Bodily dissociation · Tactile hallucination
Appetite enhancement · Bodily heaviness · Headache · Laughter fits · Nausea · Pain suppression · Restlessness · Spontaneous body sensations · Tactile euphoria · Bodily pressures · Body schema distortion · Constipation · Excessive sweating · Nausea suppression · Tingling / electric sensations · Trembling · Vibrations / buzzing · Vomiting · Breathing alteration · Pupil dilation · Involuntary body movements · Nystagmus (eye wobbles) · Stimulation · Bodily dissociation · Tactile hallucination
Confusion · Focus suppression · Information processing suppression · Memory fragmentation · Thought disorganization · Analysis suppression · Motivation suppression · Thought deceleration · Thought loops · Aesthetic enhancement · Cognitive dysphoria · Cognitive euphoria · Delusions of sobriety · Immersion enhancement · Introspection enhancement · Language suppression · Novelty enhancement · Openness enhancement · Suggestibility enhancement · Creativity enhancement · Humor enhancement · Conceptual thinking · Multiple thought streams · Pattern recognition enhancement · Thought connectivity · Amnesia · Delirium · Delusions
Memory fragmentation · Thought disorganization · Analysis suppression · Motivation suppression · Thought deceleration · Thought loops · Aesthetic enhancement · Cognitive dysphoria · Cognitive euphoria · Immersion enhancement · Introspection enhancement · Language suppression · Novelty enhancement · Openness enhancement · Suggestibility enhancement · Creativity enhancement · Humor enhancement · Conceptual thinking · Multiple thought streams · Pattern recognition enhancement · Thought connectivity · Amnesia · Delirium · Delusions
Emotional enhancement · Emotional lability · Irritability · Simultaneous emotions · Anxiety suppression
Anxiety suppression
Disinhibition · Emotional susceptibility · Social connection · Flow state · Sociability enhancement · Communication enhancement · Cognitive disconnection
Sociability enhancement · Communication enhancement · Cognitive disconnection
Timeline
Onset timing is unpredictable via oral route. First effects emerge gradually — subtle mood shift and mild body awareness. Gastrointestinal absorption and first-pass CES1 metabolism introduce variability.
Full cannabinoid intoxication — euphoria, sedation, cognitive impairment, and perceptual distortion at maximum intensity. Duration and peak timing are poorly characterized for oral administration.
Effects gradually return toward baseline within total 2–3 hour window. Residual sedation and cognitive slowing may persist.
⚠ Do not drive or operate machinery for at least 4 hours after oral ingestion.
Safety[edit]
- Acute toxicity
- High
- Chronic toxicity
- Moderate
- Withdrawal
- Moderate
- Tolerance buildup
- moderate
- Tolerance reset
- 10.5 days
- Physical
- Moderate
- Psychological
- Moderate
- Compulsive redosing
- Moderate
- Dose escalation
- Moderate
- Cross-tol.
- cannabinoids
Toxicity
No lethal dose has been established for 5F-PB-22 in any species.safety citation needed
Acute toxicity
Multiple deaths have been attributed to 5F-PB-22. In the United States, four postmortem cases reported sudden death at blood concentrations of 1.1–1.5 ng/mL;[3] a German case involved just 0.37 ng/mL with alcohol co-detected;[19] and a UK case certified combined alcohol and synthetic cannabinoid toxicity as the cause.[20]
Blood concentrations in impaired but surviving individuals (0.10–5.0 ng/mL) overlap substantially with fatal cases (0.37–1.5 ng/mL).[7][3] There is no reliably safe blood level — individual tolerance, polydrug use, and individual variation all determine whether a given concentration proves fatal.
Class-level adverse effects
A systematic review of approximately 4,000 synthetic cannabinoid presentations describes the class-level profile[21]:
- Common: Rapid heart rate (37–77% of presentations), agitation (16–41%), nausea (13–94%). Most presentations resolve with supportive care within 8 hours.
- Severe: Heart attack, stroke, blood clots, acute kidney injury, seizures, first-episode psychosis, self-harm, severe vomiting, muscle breakdown.
- Rare/critical: Multiple organ failure,[22] bleeding in the brain, bleeding disorders (associated with contaminated products).
Neurodevelopmental risk
Cell culture studies found that biologically relevant concentrations doubled neuronal growth through a cannabinoid receptor mechanism.[18] No developmental toxicity studies have been published for 5F-PB-22 in humans or animals.
Psychological risks
Full cannabinoid receptor activation without any moderating influence substantially increases psychosis risk compared to cannabis.[17] Class-level data identify first-episode psychosis, paranoia, and acute agitation as recognized complications.[21] The extreme potency of 5F-PB-22 may compress the dose range at which psychotic symptoms emerge.
Anxiety, Paranoia, and delusions are reported in community data but have not been studied under controlled conditions.
Tolerance and dependence
No study has directly measured tolerance development for 5F-PB-22. Based on cannabinoid class pharmacology, CB1 receptors downregulate with repeated full agonist exposure; full tolerance reset is estimated at approximately 1.5 weeks.safety citation needed
Physical and psychological dependence have been documented for synthetic cannabinoids as a class.[6] Withdrawal symptoms include Anxiety, Nausea, insomnia, and irritability.[23] Tolerance is a critical confounder when interpreting blood concentrations from fatal cases — the same level can be lethal in a naive user and survivable in a tolerant one.[19]
Drug interactions
The most dangerous documented interaction is with alcohol. Both substances depress the central nervous system, producing additive suppression of breathing and cardiovascular function. Liver enzymes convert 5F-PB-22 into a novel compound (ethyl ester) when alcohol is present,[16][15] and multiple fatal cases have involved high blood alcohol levels.[20][19]
Additive central nervous system depression is also expected with opioids, benzodiazepines, and other sedatives. Multiple CNS-active substances were co-detected in fatality case series.[19]
Contraindications
No substance-specific contraindication data exist for 5F-PB-22. The following are inferred from cannabinoid pharmacology and class-level adverse event data:
- Heart conditions (absolute): Full cannabinoid activation produces rapid heart rate and may trigger heart attacks or dangerous rhythm disturbances.[21]inferred
- Psychotic disorders or family history of psychosis (absolute): Full cannabinoid activation without any moderating influence substantially elevates psychosis risk.[17]inferred
- Concurrent alcohol use (absolute): Documented fatalities and a unique metabolic interaction establish this as a high-risk combination.[16][20]inferred
- Pregnancy (absolute): In vitro evidence of cannabinoid-mediated effects on neuronal development raises concern.[18]inferred
- Liver impairment (relative): The primary breakdown enzyme is hepatic; impaired function could extend exposure to the parent compound.inferred
- Kidney impairment (relative): Acute kidney injury is reported in class-level synthetic cannabinoid data.[21]inferred
- Seizure disorders (relative): Seizures are reported in synthetic cannabinoid presentations.[21]inferred
Harm Reduction[edit]
Forms & Identification
5F-PB-22 is rarely encountered as a pure substance. It reaches users almost exclusively through herbal blends ("Spice") — the compound dissolved in solvent and sprayed onto plant material — or infused into paper for use in custodial settings.[5] In both cases, dosing precision is impossible.
Concentration varies between batches, within a batch, and across different areas of the same piece of paper or herbal material.
Standard urine drug tests for cannabis may not detect synthetic cannabinoids. Forensic confirmation requires specialized laboratory testing targeting specific metabolites.[14]
Guidelines
- Start with the smallest possible amount — a single shallow inhalation, or a portion of infused paper far smaller than what others may suggest.
- Wait at least 15 minutes before considering any additional dose. Full intensity may not be apparent immediately.
- Never use alone. A sober observer who can call for help is a critical safety measure.
- Avoid all alcohol before, during, and after use. The combination has been directly linked to fatalities and creates a unique toxic metabolite.[16]
- Avoid all other sedatives, including opioids and benzodiazepines.
- Do not drive or operate machinery. Blood concentrations associated with impairment overlap with those found in fatal cases.[7]
Set & Setting
The compressed dose-response curve means environmental preparation carries less protective value than it does for substances with wider safety margins. A calm, familiar environment with a sober companion present is the minimum baseline.
The most common route of use is inhalation, which produces a rapid onset. Acute crises can develop quickly and without warning.
Aftercare & integration. The short duration of acute effects may create a false sense of rapid recovery. Residual cognitive impairment — thought deceleration, impaired short-term memory, and reduced coordination — can persist for hours beyond the subjective experience.
Hydration, light food, and rest support recovery. Avoid driving and demanding cognitive tasks for the remainder of the day. Anxiety, paranoia, or perceptual disturbances persisting beyond 24 hours warrant medical evaluation — these may indicate the onset of a psychiatric episode requiring professional support.
Recovery & Support
Regular synthetic cannabinoid use can produce physical and psychological dependence. Withdrawal symptoms include anxiety, nausea, insomnia, and irritability.[23] Withdrawal is not life-threatening but may be distressing enough to drive continued use.
Medical support may include benzodiazepines for symptom relief; some clinicians report benefit from quetiapine.[23] Anyone having difficulty stopping use should consult a healthcare provider or contact a substance use helpline.
Recovery resources, crisis lines, and support pathways → View all
Emergency Response
Recognizing an emergency:
- Unresponsiveness or inability to be roused
- Seizures or rigid, jerking movements
- Chest pain or clutching at the chest
- Severe agitation, self-harm, or psychotic behavior (paranoid delusions, loss of contact with surroundings)
- Vomiting while unconscious or semiconscious
Immediate steps:
- 1. Call emergency services immediately. Do not wait to see if symptoms improve.
- 2. Place an unresponsive person in the recovery position (on their side, airway clear).
- 3. Do not restrain a seizing person — clear the area of hard objects and protect the head.
- 4. Do not induce vomiting.
- 5. Stay with the person until help arrives.
What to tell the dispatcher: A synthetic cannabinoid was used (name it if known), how much and when, and what symptoms are present. Good Samaritan laws in many jurisdictions protect people who call for help during a drug emergency.
No reversal agent exists for synthetic cannabinoid overdose. Treatment is supportive care only.
Legal Status[edit]
5F-PB-22 is internationally controlled under the 1971 United Nations Convention on Psychotropic Substances (Schedule II, placed 2018);[9] most major jurisdictions have also enacted specific controls or blanket new psychoactive substance legislation covering this compound.
| Jurisdiction | Classification | Key provisions |
|---|---|---|
| United States | Schedule I (Controlled Substances Act) | Temporary placement 10 January 2014;[8] permanent scheduling September 2016[4] |
| United Kingdom | Class B (Misuse of Drugs Act 1971) | December 2016 MDA amendment; also covered under Psychoactive Substances Act 2016 from 26 May 2016 |
| China | Controlled substance | Controlled from October 2015 |
| Canada | Controlled (CDSA) | Covered under quinolinyl indole-carboxylate structural class provisions |
| Australia | Prohibited import | Criminal Code Regulations |
| United Nations | Schedule II (1971 Convention) | Placed 2018[9] |
| Japan | Controlled (specific date unconfirmed) | PB-22 (parent) identified in Japanese herbal blends 2012–2013; scheduling action likely but date not confirmedcitation needed |
| European Union | Varies by member state | No EU-wide specific control; covered under blanket NPS legislation in many member states |
Ten positional isomers of 5F-PB-22 exist, not all of which are explicitly scheduled. Analytical differentiation requires specialized mass spectrometry techniques.[11][24]
Legal status changes frequently and varies by jurisdiction. This information is not legal advice. Verify current status in the relevant jurisdiction before drawing any conclusions.
references
- [1] ^abcDe Luca MA, Castelli MP, Loi B, Porcu A, Martorelli M, Miliano C, Kellett K, Davidson C, Stair JL, Schifano F, Di Chiara G (2016) Native CB1 receptor affinity, intrinsic activity and accumbens shell dopamine stimulant properties of third generation SPICE/K2 cannabinoids: BB-22, 5F-PB-22, 5F-AKB-48 and STS-135. — Neuropharmacology doi:10.1016/j.neuropharm.2015.11.017
- [2] ^abWohlfarth A, Gandhi AS, Pang S, Zhu M, Scheidweiler KB, Huestis MA (2014) Metabolism of synthetic cannabinoids PB-22 and its 5-fluoro analog, 5F-PB-22, by human hepatocyte incubation and high-resolution mass spectrometry. — Analytical and Bioanalytical Chemistry doi:10.1007/s00216-014-7668-0
- [3]
- [4] ^abcDEA (Drug Enforcement Administration) (2016) Schedules of Controlled Substances: Placement of PB-22, 5F-PB-22, AB-FUBINACA and ADB-PINACA into Schedule I. Final rule. — Federal Register PMID:27632803
- [5] ^abcNorman C, McKirdy B, Walker G, Dugard P, NicDaéid N, McKenzie C (2021) Large-scale evaluation of ion mobility spectrometry for the rapid detection of synthetic cannabinoid receptor agonists in infused papers in prisons. — Drug Testing and Analysis doi:10.1002/dta.2945
- [6] ^abGunderson EW, Haughey HM, Ait-Daoud N, Joshi AS, Hart CL (2012) "Spice" and "K2" herbal highs: a case series and systematic review of the clinical effects and biopsychosocial implications of synthetic cannabinoid use in humans — The American journal on addictions doi:10.1111/j.1521-0391.2012.00240.x