Fladrafinil

A fluorinated cousin of adrafinil — the old prodrug that converts to modafinil-family compounds in the liver. Related entries: Modafinil and Armodafinil.

Fladrafinil (CRL-40,941) is a bisfluoro analogue of adrafinil, which is itself a prodrug of modafinil. So the proposed mechanism is the same as modafinil's — atypical dopamine-transporter inhibition alongside effects on histamine, orexin and noradrenaline. The key difference is not pharmacological sophistication but regulatory position: modafinil is a scheduled prescription drug with a label, and fladrafinil is a research chemical with none, sold precisely because it is not the scheduled molecule.

A 1970s-80s French patent-era literature and almost nothing modern: no therapeutic efficacy trials exist; limited human metabolism data (a small 2026 volunteer study characterizing conversion) is the extent of the modern record. Everything users expect from it is borrowed from modafinil's dossier.

• NONE. There is no human clinical trial of fladrafinil of any size or phase. It never entered clinical development.
• Everything claimed for it is extrapolated from modafinil and adrafinil, which are different molecules with different regulatory and evidence positions.
• Adrafinil, its closest relative with any human record, was withdrawn from the market and carries a liver-enzyme concern from its metabolism — a consideration frequently ignored when fladrafinil is discussed as an unregulated modafinil substitute.
• Modafinil's own label carries serious warnings — severe rash including Stevens-Johnson syndrome, multisystem hypersensitivity, and serious psychiatric reactions including mania, delusions and suicidal ideation. There is no basis for assuming an unstudied analogue avoids them.
• Sold as research-chemical powder of unverified identity, concentration and purity.

Human pharmacokinetics have never been characterised — no bioavailability, half-life or clearance figure exists for people. Any number in circulation is extrapolated from modafinil. As a wakefulness-promoting analogue it would be expected to affect sleep, and it is prohibited in sport.

Adrafinil-class compounds carry a specific concern the modafinil entry does not: the prodrug conversion step works the liver, and adrafinil's own history includes hepatic-enzyme elevation reports with chronic use — fladrafinil inherits the question without the monitoring. Add unverifiable purity and the usual sleep-architecture costs of any long-half-life wakefulness agent.

• Everyone — an unstudied analogue of a drug whose own label carries serious warnings, with no human data of any kind
• Anyone relying on hormonal contraception, given the unresolved interaction question
• Anyone with a history of serious drug rash or psychiatric illness
• Anyone pregnant or breastfeeding

• No characterised human interaction profile exists.
• Modafinil induces CYP3A4 and reduces the effectiveness of hormonal contraception. Whether this analogue does the same is unknown, which is not the same as knowing it does not — anyone relying on hormonal contraception should treat that as an open risk.
• Other stimulants, where cardiovascular and sleep effects would be expected to be additive.

• There is no established monitoring for an uncharacterised research chemical, and offering a panel would imply a safety profile nobody has measured.
• Any rash at all is a stop-and-seek-care event given what is on the modafinil label — an unstudied analogue is not a reason to worry less about that.
• Liver symptoms, given the concern associated with adrafinil.
• Sleep, which is what these compounds borrow against.

Nothing is established about stopping because nothing is established about taking it. What people describe is the fatigue and sleep rebound that follows any wakefulness-promoting compound — which is the sleep debt arriving rather than a withdrawal syndrome.

US: unscheduled and not FDA-approved for human use. (Modafinil itself is Schedule IV.)

Papers about this compound, not proof of the claims above. A title says what was studied, which is sometimes a negative result or a different question entirely.

• Investigations Into the Metabolism and Elimination of Flmodafinil and Fladrafinil for Sports Drug Testing Purposes
  Drug Test Anal, 2026
• 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: formation of 1,1,2,2-tetraphenylethane and its tetra fluoro analog
  Drug Test Anal, 2017

• Investigations Into the Metabolism and Elimination of Flmodafinil and Fladrafinil for Sports Drug Testing PurposesDrug Test Anal · 2026