Flmodafinil (CRL-40,940) and fladrafinil (CRL-40,941) are fluorinated modafinil analogs, and adrafinil is a prodrug the body converts to modafinil. The cited fluoro-analog studies measure drug detection; France's HAS reviewed older placebo-controlled adrafinil trials. The only controlled human data for the fluoro pair are urine and blood levels after a single 20 mg dose in six volunteers. Adrafinil has one case report of persistent orofacial dyskinesia. All three, plus modafinil, are S6.A stimulants on the 2026 WADA Prohibited List.
Summary drafted from this entry’s sources; editorial review pending.
01Key questions
Is flmodafinil stronger than modafinil?
Nobody knows. There is no human trial comparing them, or testing flmodafinil for cognition at all. The two PubMed papers on it are drug-testing chemistry. A mouse study of lauflumide (NLS-4) found longer wakefulness than modafinil, but that paper never says NLS-4 is flmodafinil.184
What is the difference between flmodafinil and fladrafinil?
Fladrafinil is a prodrug of flmodafinil, in the same way adrafinil is a prodrug of modafinil. After a 20 mg dose, peak urine and blood levels of fladrafinil were lower than after flmodafinil, and the flmodafinil peak came slightly later.1
Is adrafinil safe?
Adrafinil has older clinical trials and a French prescribing history. One published case describes orofacial dyskinesia persisting four months after stopping. The case does not establish how often this occurs.5
Are these banned in sport?
Yes. Flmodafinil and fladrafinil were added by name to the 2026 WADA Prohibited List as S6.A non-specified stimulants, next to adrafinil and modafinil, which have been banned since 2004. All are prohibited in competition, and detection windows are relatively long.12
What would change this rating?
A placebo-controlled human trial of cognition or alertness, with safety monitoring, for any of the three compounds.
Flmodafinil (CRL-40,940) and fladrafinil (CRL-40,941) are fluorinated relatives of modafinil sold online as "stronger modafinil." Adrafinil is an older prodrug that the body turns into modafinil. The cited human studies of the fluorinated pair concern drug detection. Adrafinil has older placebo-controlled trials described in France's HAS assessment. What the literature does contain is mostly drug-testing chemistry, and it is laid out below.
The trial evidence for modafinil and armodafinil themselves is on Modafinil and eugeroics. Those results do not carry over to the analogs. For another gray-market stimulant with a thin evidence base, see bromantane.
Not medical advice. Doses below are the single exposures used in the cited studies, not a regimen or a conversion between compounds.
02What these compounds are
| Name | Code | Structure | Relation |
|---|---|---|---|
| Flmodafinil | CRL-40,940 | 2-[bis(4-fluorophenyl)methylsulfinyl]acetamide | Bis-fluoro analog of modafinil (PMID 42210629) |
| Fladrafinil | CRL-40,941 | 2-[bis(4-fluorophenyl)methylsulfinyl]-N-hydroxyacetamide | Prodrug of flmodafinil (PMID 42210629) |
| Adrafinil | None (sold in France as Olmifon) | 2-((diphenylmethyl)sulfinyl)-N-hydroxyacetamide | Prodrug of modafinil (PMID 33457050) |
| Modafinil | None | 2-((diphenylmethyl)sulfinyl)acetamide | The parent drug. Its pharmacokinetics (PMID 12537513) do not describe the fluoro analogs |
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No published study gives an "equivalent dose" between modafinil and either fluoro analog.
03Claims versus evidence
| Claim | What the evidence shows | Verdict |
|---|---|---|
| Flmodafinil is a stronger cognitive enhancer than modafinil | No human efficacy or head-to-head trial exists. As of October 2026, PubMed lists two papers on flmodafinil or fladrafinil, and both are analytical chemistry. | Unsupported |
| There is human data | One elimination study: six volunteers took 20 mg of either compound and had urine and blood levels measured (PMID 42210629). No effects were measured. | Drug levels only |
| Fladrafinil is just longer-lasting modafinil | The same study treats fladrafinil as a prodrug of flmodafinil, not of modafinil, and its peak levels were lower than after flmodafinil. | Unsupported |
| A mouse study shows the analog outlasts modafinil | Lauflumide (NLS-4) at 64 mg/kg kept mice awake longer than modafinil at 150 mg/kg (PMID 30158846). The paper never says NLS-4 is flmodafinil. | Not flmodafinil evidence |
| Adrafinil is a harmless over-the-counter modafinil | Older placebo-controlled trials appear in the French clinical dossier. One case of orofacial dyskinesia that persisted four months after stopping (PMID 15300665). No published rate of liver-enzyme changes. | Unsupported |
| These are allowed in sport | The 2026 WADA Prohibited List names all four as S6.A non-specified stimulants, banned in competition. | False |
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04Human evidence
Flmodafinil and fladrafinil: drug levels, not effects
Krug et al., German Sport University Cologne, Drug Testing and Analysis 2026;18(8):1076–1087 (PMID 42210629). Six volunteers took a single 20 mg dose of either flmodafinil or fladrafinil. Urine and dried blood spots were analysed by LC-HRMS, with detection limits of 0.2 to 4 ng/mL. The study did not measure cognition, sleepiness or side effects.
| Sample | Flmodafinil peak | Fladrafinil peak |
|---|---|---|
| Urine | 191 to 891 ng/mL | 52 to 111 ng/mL |
| Blood (dried blood spot) | 45 to 98 ng/mL | 11 to 35 ng/mL |
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Flmodafinil breaks down to flmodafinil acid and flmodafinil sulfone. The same metabolites appeared after fladrafinil, which converts to flmodafinil, so its flmodafinil peak came slightly later. The authors describe the detection windows as relatively long, which matters for tested athletes.
This is a doping-control methods paper. It does not support claims about efficacy, safety or dose equivalence with modafinil.
Adrafinil: an older modafinil prodrug
- Metabolism. Adrafinil is "primarily metabolized in vivo to an active form, i.e. modafinil" (PMID 33457050). A doping-control method lists modafinil and modafinil acid as its major metabolites in human urine (PMID 19399790).
- Movement disorder, one case. Thobois et al. (Movement Disorders 2004) reported the first case of orofacial dyskinesia attributed to adrafinil. The movements had not resolved four months after stopping the drug and improved only after tetrabenazine was started (PMID 15300665). One case gives no rate.
- Hair testing. One volunteer took a single 200 mg dose. Beard hair collected 10 days later contained adrafinil at 0.8 ng/mg and modafinil at 0.5 ng/mg. In a trafficking case, head hair held modafinil (6.8 to 13.9 ng/mg) but no adrafinil, which the authors read as modafinil use rather than adrafinil use (PMID 33457050).
- Rat assay. An LC-MS/MS method measured adrafinil in rats after oral dosing (PMID 18723408). It reports no human-relevant dose, half-life or bioavailability.
What does not exist yet
- France’s HAS reviewed older placebo-controlled adrafinil studies, including the Hugonot trial with 104 randomized patients. A title-only PubMed search does not capture that clinical dossier.
- An October 2026 ClinicalTrials.gov search found no trials under these three names; adrafinil’s older French trials predate routine registration.
05Animal evidence
Luca et al., Frontiers in Neuroscience 2018;12:519 (PMID 30158846). In C57BL/6J mice injected at light onset, lauflumide (NLS-4) at 64 mg/kg produced significantly longer wakefulness than modafinil at 150 mg/kg over 24 hours of EEG recording. Neither drug caused a significant sleep rebound, and modafinil was followed by more NREM sleep than NLS-4.
The paper never names flmodafinil, CRL-40,940 or its structure, so this result cannot be credited to flmodafinil. It is also a mouse result, not a human one.
06Analytical chemistry
Dowling et al., Drug Testing and Analysis 2017;9(3):518–528 (PMID 27928893), showed that modafinil, modafinic acid, adrafinil, CRL-40,940 and CRL-40,941 break down in a heated GC injector, forming products such as 1,1,2,2-tetraphenylethane and a tetrafluoro analog. That matters for correct identification in lab testing. It says nothing about safety or potency in people.
Lu et al. (PMID 19399790) validated urine detection of adrafinil, modafinil and modafinil acid for doping control. Detection sensitivity is not evidence of a cognitive effect.
07Legal and sport status
Flmodafinil and fladrafinil were added by name to the 2026 WADA Prohibited List, in force from 1 January 2026, as S6.A non-specified stimulants. Adrafinil and modafinil are on the same list, and all four are prohibited in competition (NADA summary of the 2026 list; PMID 42210629). WADA first banned adrafinil and modafinil in 2004 (PMID 33457050).
Neither fluoro analog is an approved medicine anywhere. Anti-doping agencies describe them as unapproved drugs found in supplements and "research only" products. Modafinil's prescription status does not extend to them.
08What to watch
- The only controlled human exposure to the fluoro pair used 20 mg and measured urine and blood levels, not performance or safety.
- If a paper confirms that lauflumide (NLS-4) is flmodafinil, the 2018 mouse data would apply to it. Until then they do not.
- The cited studies do not establish how often adrafinil raises liver enzymes in people.
09Who paid, and how it got here
Who funded the key studies on this page, the favourable and the unfavourable alike, and how its legal status came about. From each paper’s funding and conflict-of-interest statements, trial registries and official documents; checked 1 Nov 2026. Why we show this
How it got here
- The 2026 WADA list names adrafinil, modafinil, flmodafinil and fladrafinil under S6.A. They are prohibited in competition. WADA 2026 Prohibited List
- Adrafinil was authorized in France in 1981 as Olmifon. HAS reported in November 2011 that it was no longer marketed and recommended removing reimbursement because the assessed benefit remained insufficient. HAS Olmifon assessment, 2 November 2011
- In 2015, the FTC settlement with Cephalon provided $1.2 billion for purchasers overcharged for Provigil. The FTC said Cephalon paid four generic companies over $300 million through side deals to delay competition until April 2012. FTC Cephalon pay-for-delay settlement
Who paid for the key studies
- Krug fluoro-analog elimination study; n=6Measured drug elimination and detection, not cognition.Funding and interests: WADA, Manfred-Donike Institute for Doping Analysis and Germany's Federal Ministry of the Interior and Community. Paper's funding statement
- Luca NLS-4 mouse EEG experiment; 8 mice per treatmentNLS-4 prolonged wakefulness relative to modafinil in mice.Funding and interests: University of Lausanne and NLS Pharma; four authors reported advisory-board or speaking compensation from unnamed organizations. Paper's funding statement
- Thobois adrafinil dyskinesia case report; n=1Persistent orofacial dyskinesia after stopping adrafinil.Funding and interests: No funding statement in the PubMed record PubMed funding record
- Ameline adrafinil hair study; one volunteer plus one forensic caseDetected adrafinil and modafinil after a single exposure.Funding and interests: Authors reported no potential conflicts of interest. Conflict-of-interest statement
What studies and practitioners report
Amounts as reported in the cited sources: trial doses with the population studied, and practitioner-reported ranges marked as such. Not medical advice.
- Trial 20 mg, single oral dose · flmodafinil or fladrafinil, elimination study (no effects measured) healthy volunteers, n=6 PMID 42210629
- Trial 200 mg, single oral dose · adrafinil, hair-testing study one volunteer PMID 33457050
Further reading: detailed protocols
10Connections
11Sources
- Krug O, Guddat S, Görgens C, Walpurgis K, Toma F, Thomas A, Thevis M. Investigations into the metabolism and elimination of flmodafinil and fladrafinil for sports drug testing purposes. Drug Test Anal. 2026;18(8):1076–1087. doi 10.1002/dta.70100 . PMID 42210629 .PubMed 42210629 · DOI 10.1002/dta.70100
- Ameline A, Gheddar L, Raul JS, Kintz P. Identification of adrafinil and its main metabolite modafinil in human hair. Forensic Sci Res. 2020;5(4):322–326. doi 10.1080/20961790.2019.1704482 . PMID 33457050 .PubMed 33457050 · DOI 10.1080/20961790.2019.1704482
- Robertson P Jr, Hellriegel ET. Clinical pharmacokinetic profile of modafinil. Clin Pharmacokinet. 2003;42(2):123–137. PMID 12537513 .PubMed 12537513
- Luca G, Bandarabadi M, Konofal E, Lecendreux M, Ferrié L, Figadère B, Tafti M. Lauflumide (NLS-4) is a new potent wake-promoting compound. Front Neurosci. 2018;12:519. doi 10.3389/fnins.2018.00519 . PMID 30158846 .PubMed 30158846 · DOI 10.3389/fnins.2018.00519
- Thobois S, Xie J, Mollion H, Benatru I, Broussolle E. Adrafinil-induced orofacial dyskinesia. Mov Disord. 2004;19(8):965–966. PMID 15300665 .PubMed 15300665
- Lu J, et al. Doping control analysis for adrafinil and its major metabolites in human urine. Rapid Commun Mass Spectrom. 2009;23(11):1592–1600. PMID 19399790 .PubMed 19399790
- Rao RN, Shinde DD, Talluri MV, Agawane SB. LC-ESI-MS determination and pharmacokinetics of adrafinil in rats. J Chromatogr B. 2008;873(1):119–123. PMID 18723408 .PubMed 18723408
- Dowling G, Kavanagh PV, Talbot B, O'Brien J, Hessman G, McLaughlin G, et al. Outsmarted by nootropics? An investigation into the thermal degradation of modafinil, modafinic acid, adrafinil, CRL-40,940 and CRL-40,941 in the GC injector. Drug Test Anal. 2017;9(3):518–528. PMID 27928893 .PubMed 27928893
12Entry history
Latest content update.
Heretic informs and never prescribes. Where amounts appear, they describe what published studies used. Talk to a qualified clinician before acting on anything here.