Fladrafinil

Overview

Fladrafinil (CRL-40,941) is a non-peptide synthetic eugeroic and the bis(4-fluorophenyl)-substituted analog of adrafinil, retaining adrafinil's N-hydroxyacetamide group. Never approved or marketed as a pharmaceutical in any jurisdiction, it is sold exclusively as an unregulated research chemical. Added to WADA's S6 (Stimulants, non-specified) category on the 2026 Prohibited List, effective 1 January 2026.

Mechanism of Action

No experimentally confirmed human mechanism of action has been published for fladrafinil. By structural analogy to modafinil and adrafinil, a dopamine-reuptake-inhibition-based wakefulness-promoting mechanism is hypothesized, but this has not been directly demonstrated for fladrafinil in any peer-reviewed study. Fladrafinil acts as a prodrug for flmodafinil, as confirmed by a 2026 pharmacokinetics study.

Research Summary

No clinical trials for any therapeutic indication exist; no FDA approval has been granted. The only identified human data are: (1) a 2026 peer-reviewed pharmacokinetics/metabolism study for anti-doping purposes (Krug et al., Drug Testing and Analysis), which administered fladrafinil orally to healthy volunteers and confirmed metabolism to flmodafinil, flmodafinil acid, and flmodafinil sulfone; and (2) unverified patent-holder claims from 1984 describing oral 50 mg capsules for hypersomnia/psychasthenia with reported 'excellent results' over 2–8 weeks—this is not an independently published or peer-reviewed trial. Animal studies (mice/rats, intraperitoneal, 16–256 mg/kg) from the 1984 Lafon patent reported reduced barbiturate-induced sleep duration, increased spontaneous motor activity, reduced inter-group aggression, improved motor recovery following hypoxic stress, and prolonged amphetamine-induced stereotypy.

Reported Side Effects

• No peer-reviewed toxicology or adverse-event data in humans at any dose
• Sold as unregulated research chemical with no quality/purity oversight
• WADA-prohibited (S6, 2026) — risk for athletes subject to anti-doping testing
• Acts as prodrug for flmodafinil; does not metabolize to modafinil
• Mechanism of action unknown; safety profile uncharacterized

Compare Fladrafinil with Others

Research References

• Fladrafinil, CID 13316557.
• Fladrafinil (Wikipedia).
• Investigations Into the Metabolism and Elimination of Flmodafinil and Fladrafinil for Sports Drug Testing Purposes. 2026.
• Halogenobenzhydrylsulfinylacetohydroxamic acids (US Patent 4,489,095). 1984.

Frequently asked questions

Has Fladrafinil been independently lab-tested?

Disclosed Labs has collected 2 Certificates of Analysis (COA) for Fladrafinil from 1 independent testing lab. 1 vendor has submitted material for testing. Products average 99.6% tested purity across the corpus. Full testing data is available at https://www.disclosedlabs.com/peptides/fladrafinil/testing.

How does Fladrafinil work?

No experimentally confirmed human mechanism of action has been published for fladrafinil. By structural analogy to modafinil and adrafinil, a dopamine-reuptake-inhibition-based wakefulness-promoting mechanism is hypothesized, but this has not been directly demonstrated for fladrafinil in any peer-reviewed study. Fladrafinil acts as a prodrug for flmodafinil, as confirmed by a 2026 pharmacokinetics study.

What does the research say about Fladrafinil?

No clinical trials for any therapeutic indication exist; no FDA approval has been granted. The only identified human data are: (1) a 2026 peer-reviewed pharmacokinetics/metabolism study for anti-doping purposes (Krug et al., Drug Testing and Analysis), which administered fladrafinil orally to healthy volunteers and confirmed metabolism to flmodafinil, flmodafinil acid, and flmodafinil sulfone; and (2) unverified patent-holder claims from 1984 describing oral 50 mg capsules for hypersomnia/psychasthenia with reported 'excellent results' over 2–8 weeks—this is not an independently published or peer-reviewed trial. Animal studies (mice/rats, intraperitoneal, 16–256 mg/kg) from the 1984 Lafon patent reported reduced barbiturate-induced sleep duration, increased spontaneous motor activity, reduced inter-group aggression, improved motor recovery following hypoxic stress, and prolonged amphetamine-induced stereotypy.