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Hydrafinil, also called 9-fluorenol or 9-hydroxyfluorene, is a simple laboratory chemical that Cephalon tested around 2012 while looking for a successor to the wakefulness drug modafinil; despite the similar sounding name it is not chemically related to modafinil and belongs to a different chemical family. In the single rat experiment that exists it kept animals awake longer than modafinil did at the same injected dose, after which the programme was dropped with no published reason and never reached a human trial. The entire human record is one anti-doping study in which three healthy men each swallowed a single 50 mg dose so that laboratories could learn to detect it in urine; nothing at all has been published on whether it improves alertness, attention or fatigue in people, and nothing has been published on its safety. It is banned in competition by the World Anti-Doping Agency and is not an approved medicine in any country.
- Clean wakefulness that simply holds
- Focus sharpens without the jitter
- Outlasted modafinil in rat wakefulness testing
- Fatigue fades; heavy stimulation never arrives
- The refined, gentler side of eugeroics
- As a modafinil-like agent, headache, nausea, and insomnia would be plausible class effects
Overview
Hydrafinil is the common name for 9-fluorenol (chemical name 9H-fluoren-9-ol), a synthetic compound sold as a research chemical and marketed as a eugeroic, a drug intended to promote wakefulness and alertness. It is frequently described as an analog or alternative to modafinil, the prescription wakefulness-promoting agent used for narcolepsy and shift-work sleep disorder, and it is grouped with modafinil in the broad category of atypical dopamine transporter (DAT) inhibitors and cognitive enhancers [1][2].
It is important to state plainly that hydrafinil itself has essentially no peer-reviewed pharmacological or clinical literature; it has not been characterized in published human trials, and claims about its potency relative to modafinil come from vendor sources rather than controlled studies. What can be described with confidence is the pharmacology of the modafinil class to which it is said to belong. Modafinil is a wake-promoting compound with recognized potential for cognitive enhancement that acts by targeting the dopamine transporter with moderate selectivity, inhibiting reuptake and raising dopamine levels in the synaptic cleft [2]. Extensive medicinal-chemistry work has produced modafinil analogues with a distinctive atypical DAT-inhibitor profile, meaning they block dopamine reuptake without producing the strong locomotor stimulation and abuse-related effects of cocaine-like stimulants [1][3][4].
In clinical use, modafinil reduces excessive daytime sleepiness, and reviews of pharmaceutical cognitive enhancement place it among the most studied agents for attention and vigilance [5][6]. Hydrafinil is not an approved medicine, is not evaluated by regulators as a therapeutic, and is sold only as a research chemical. Its structural class and marketed purpose place it alongside modafinil and its analogues, but any expectation of similar effects rests on that resemblance rather than on direct evidence for the compound itself [1][2].
- Hydrafinil is chemically 9-fluorenol, a fluorene derivative rather than a true member of the modafinil sulfoxide family it is marketed to resemble.
- Despite widespread online claims of high potency, no controlled human study of hydrafinil has ever been published.
- In the modafinil class, wakefulness comes from atypical dopamine reuptake blockade that avoids the amphetamine-like release pattern.
Mechanism
Because hydrafinil itself has not been studied in controlled pharmacology, its presumed mechanism is best understood through the modafinil class it is marketed to imitate. The defining action of that class is atypical inhibition of the (). By binding DAT and blocking the reuptake of , modafinil raises extracellular dopamine and thereby promotes wakefulness and supports attention; unlike amphetamines, it does not act primarily as a dopamine releaser, which gives it a smoother, lower-stimulation profile [2]. Medicinal-chemistry studies of modafinil analogues have produced compounds with high affinity, with lead molecules reaching binding constants in the low-nanomolar range (for example about 2.5 nM), yet still lacking the strong locomotor stimulation seen with cocaine, the hallmark of the atypical DAT-inhibitor profile [1].
This atypical profile is the mechanistic reason the class is attractive as a wakefulness and focus aid: microdialysis and voltammetry work shows that small structural changes tune how these compounds affect tonic and phasic in reward-related brain regions, and that some analogues avoid the cocaine-like surges associated with abuse [4]. The wakefulness benefit is downstream of sustained dopaminergic tone in circuits that regulate arousal.
The clinical benefits documented for the parent compound frame what a modafinil-like agent is expected to do. In a double-blind randomized trial in narcolepsy, modafinil reduced excessive daytime sleepiness, lowering Epworth Sleepiness Scale scores by roughly 6.9 points over eight weeks, and it is repeatedly identified in systematic reviews as a leading pharmaceutical cognitive enhancer for attention and vigilance [5][6]. For hydrafinil, these outcomes are a reasonable expectation based on class membership rather than a demonstrated fact; no comparable trials of hydrafinil exist, and its true potency, safety, and effect size in humans remain uncharacterized [1][2].
receptor fingerprint
(, SLC6A3), rat striatal membranesWeak binder; displaces the cocaine-site radioligand [3H]WIN-35,428. Binds DAT roughly 2.4-fold more weakly than modafinil measured in the same assay in the same paper (modafinil IC50 3,700 nM), yet produced more wakefulness, which is why the authors concluded DAT does not explain the effect.
Wakefulness in rat (in vivo functional endpoint, not a molecular target)Wake-promoting. Total time awake over the 3 h post-dose window at 100 mg/kg i.p. was 2.717 h, versus 1.95 h for modafinil at the same dose in the same table; that ratio is the origin of the widely quoted 39 percent figure.
Cytochrome P450 / NADPH-cytochrome P450 reductase (as substrate, not inhibitor)Substrate. Oxidised by CYP to 9H-fluoren-9-one; the reaction is oxygen-dependent and blocked by SKF 525-A and carbon monoxide, and the ketone is reduced back to the alcohol by NADPH-cytochrome P450 reductase, giving a redox couple rather than a one-way route.
receptor (MCF-7 based reporter assay)No significant estrogenic activity at 3 to 30 uM. The 2-hydroxyfluorene and 3-hydroxyfluorene positional isomers were significantly estrogenic in the same assay, so isomer identity matters.
Aryl hydrocarbon receptor (dioxin-like reporter assay)Not active at 3 to 30 uM, while the 2- and 3-hydroxyfluorene isomers were active. Also not cytotoxic up to 100 uM in the same cell panel.
Indoleamine 2,3-dioxygenase 1 (IDO1, human recombinant)Inactive. Listed only to show how thin the target data is: DAT and IDO1 are the only two molecular targets ChEMBL holds for this molecule across the entire literature.
reuptake ()weakly inhibits
Wake-promoting circuits (modafinil-like)modulates (not fully mapped)
Dosingtypical ranges, not medical advice
interested in protocols and clinical dosages? make an account to see them! ^_^
Safetyrisks and cautions, not medical advice
HUMAN SAFETY DATA: none. PubMed contains no case report, no adverse-event series, and no clinical toxicology study of hydrafinil (searched under hydrafinil, fluorenol, 9-fluorenol and 9-hydroxyfluorene). ClinicalTrials.gov returns ZERO registered trials for any of those names. Blog and vendor reports of headache, nausea, insomnia, anxiety and one hospitalisation circulate widely but have no traceable primary source and should not be presented as documented adverse effects.
INTERACTIONS: unknown. The Cephalon paper measured CYP2C19, CYP3A4 and CYP2D6 inhibition for modafinil and for other members of the series but reported no CYP value for fluorenol itself, so nothing can be said about interaction risk. Modafinil's CYP2C19 IC50 of 11 uM from that same paper belongs to modafinil and must not be transferred.
PUBLISHED IN VITRO NEGATIVES (real, and useful): 9-hydroxyfluorene was not cytotoxic up to 100 uM and showed no significant estrogenic or dioxin-like (AhR) activity at 3 to 30 uM, whereas the 2- and 3-hydroxyfluorene isomers were active in both assays (PMID 26987414).
METABOLIC CONCERN: cytochrome P450 oxidises fluoren-9-ol to 9H-fluoren-9-one and the reaction reverses via NADPH-cytochrome P450 reductase (PMID 6148207); both the alcohol and the ketone were detected in rat plasma and brain (PMID 22546675). Human exposure therefore also means fluorenone exposure, and the human toxicology of that ketone is not characterised. Human urinary metabolites are hydroxylated hydrafinil plus glucuronide and sulfate conjugates (PMID 34378339).
REGULATORY, verified against primary documents on 2026-07-28: - WADA: PROHIBITED. The 2026 WADA Prohibited List names "Hydrafinil (fluorenol)" verbatim on page 15 under S6 Stimulants, section S6.A NON-SPECIFIED STIMULANTS, prohibited IN-COMPETITION, in the same block as adrafinil, modafinil, fladrafinil and flmodafinil. As an S6.A entry it is a non-Specified Substance, which carries the harsher sanctioning path. It was NOT prohibited in 2021 (the doping paper says "if classified as prohibited by WADA"), so it was added somewhere between the 2022 and 2026 Lists; secondary sources say the 2025 List, which could not be independently confirmed because the 2024 and 2025 PDFs would not download. - DEA: NOT scheduled. The DEA List of Controlled Substances and Regulated Chemicals (137 pages, downloaded 2026-07-28) contains zero occurrences of "fluoren" or "hydrafinil". - FDA / EMA: not approved anywhere, for any indication. No registered clinical trial has ever been conducted. It is not a lawful dietary-supplement ingredient and is sold as a research chemical. No specific FDA warning letter naming hydrafinil could be located.
History
Hydrafinil is the informal name applied to 9-fluorenol, a fluorene derivative that has circulated in the nootropic and research-chemical marketplace as a purported modafinil-style wakefulness agent. Unlike the pharmaceuticals it is marketed to imitate, hydrafinil has no documented record of formal preclinical or clinical development; claims that it was studied as a potent modafinil analogue are widely repeated online but are not supported by peer-reviewed pharmacology, so much of its history is undocumented.
The underlying molecule, 9-fluorenol, is a known chemical compound long familiar to organic chemistry, but its adoption as a eugeroic reflects vendor marketing rather than a traceable discovery or approval milestone. Its presumed profile is inferred entirely from the well-characterized modafinil family, whose atypical dopamine-transporter mechanism has been mapped in detail. No regulatory body has evaluated hydrafinil as a medicine, and it exists purely as an unapproved research chemical. Consequently, its true potency, dosing, and safety in humans remain uncharacterized.
Reputation
Hydrafinil is positioned within the appealing family of atypical wakefulness promoters, the same class whose flagship, modafinil, is repeatedly identified in systematic reviews as a leading pharmaceutical cognitive enhancer for attention and vigilance. The attraction of this class lies in its mechanism: mild, selective blockade of dopamine reuptake that supports alertness and focus without the harsh stimulation or crash associated with amphetamines.
Medicinal-chemistry work on modafinil analogues has produced compounds with high dopamine-transporter affinity that nonetheless avoid cocaine-like locomotor surges, and animal studies show related agents can enhance working memory. It is essential to be candid that these encouraging findings belong to studied members of the class, not to hydrafinil itself, which has never undergone controlled human evaluation. For that reason its benefits remain a reasonable expectation based on family resemblance rather than a demonstrated fact. Interested users should treat it as an experimental substance and weigh that uncertainty carefully.
Subjective profileweighing the evidence above
Sold as a gentler modafinil on the strength of the class rather than any study of the compound itself; nobody has formally tested it in people, so the mild reputation is marketing plus anecdote. Modafinil is the honest pick if wakefulness with real data behind it is the goal.
Where to buy
1 other outlet
Suppliers
Vendors carrying Hydrafinil, with live product details and codes. Links are affiliate links that support the wiki at no cost to you.
Kimera Chems
Hydrafinil
Kimera Chems
Hydrafinil
Research
- 1984first citedMetabolism of alcohol and ketone by cytochrome P-450 oxygenase: fluoren-9-ol in equilibrium wit…
- 2013controlled trialPitolisant versus placebo or modafinil in patients with narcolepsy: a double-blind, randomised…
- 2023most recentThe association between urinary polycyclic aromatic hydrocarbon metabolites and liver function…
- 1.Heterocyclic Analogues of Modafinil as Novel, Atypical Dopamine Transporter Inhibitors.
- 2.Novel and High Affinity 2-[(Diphenylmethyl)sulfinyl]acetamide (Modafinil) Analogues as Atypical Dopamine Transporter Inhibitors.
- 3.Structure-Activity Relationships of Novel Thiazole-Based Modafinil Analogues Acting at Monoamine Transporters.
- 4.Effects of (R)-Modafinil and Modafinil Analogues on Dopamine Dynamics Assessed by Voltammetry and Microdialysis in the Mouse Nucleus Accumbens Shell.
- 5.Pitolisant versus placebo or modafinil in patients with narcolepsy: a double-blind, randomised trial.
- 6.Innovative mechanisms of action for pharmaceutical cognitive enhancement: A systematic review.
- 7.Mass spectrometric characterization of urinary hydrafinil metabolites for routine doping control purposes.
- 8.Modification of alveolar macrophage function with bis-basic ethers of fluorene and fluoren-9-substituted derivatives.
- 9.The effect of modafinil on the rat dopamine transporter and dopamine receptors D1-D3 paralleling cognitive enhancement in the radial arm maze
- 10.Wake promoting agents: search for next generation modafinil, lessons learned: part III.
- 11.Metabolism of alcohol and ketone by cytochrome P-450 oxygenase: fluoren-9-ol in equilibrium with fluoren-9-one.
- 12.Photodegradation of fluorene in aqueous solution: Identification and biological activity testing of degradation products.
13 listed here; entry last updated August 2026
Reviews
My notesprivate to this device
FAQ
How does it relate to modafinil?
It's a metabolite associated with modafinil and shares wakefulness-promoting properties. It's described as having a milder feel.
What is a eugeroic?
It's a class of wakefulness-promoting agents that aren't classic stimulants. They aim for alertness with less of a stimulant edge.
Why take it early?
Because it promotes wakefulness, later use can interfere with sleep. Morning timing is a common approach.
How well studied is it?
It's largely a research compound with limited human data. Long-term safety is not well characterized.
Adverse effects
- As a modafinil-like agent, headache, nausea, and insomnia would be plausible class effects
Notes and cautions
- Hydrafinil itself has no established human safety profile
- Overuse of wakefulness agents can disrupt normal sleep
- It is an unregulated research chemical, not an approved medicine
- Purity and contents of research-chemical products are not guaranteed