Modafinil vs armodafinil: what the labels and trials show

Key points

• Armodafinil is the R-enantiomer of modafinil, which is a 1:1 mix of R and S forms. In the US both are prescription Schedule IV drugs with the same three indications [1][2].
• The labels report a similar terminal half-life of about 15 hours. The difference is the S-form, which clears faster, so equal milligrams of armodafinil gave higher late-day blood levels in sponsor-run studies [1][19][21].
• Armodafinil’s US approval rests on four Cephalon-sponsored placebo-controlled trials, not head-to-head trials. The two head-to-head patient trials we found were small, and one is called inconclusive by its sponsor [11][16][17].
• The 2011 EU decision narrowed modafinil to narcolepsy. We found no armodafinil entry in the EMA central register, and we did not check national registers [4][6].
• We found no large head-to-head trial in healthy people. One single-night study of 107 men is the only direct comparison [18].

What is the chemical difference?

Modafinil is a racemic compound: equal parts R- and S-modafinil. Armodafinil is the single R-enantiomer, with the same molecular formula and weight [1][2]. The enantiomers do not interconvert [2]. Both labels say the enantiomers have similar pharmacological actions in animals, and both say the wakefulness mechanism is unknown [1][2]. Both forms bind the dopamine transporter in vitro [1]. How that relates to wakefulness is covered in the modafinil guide.

What is each approved for?

Neither is a research peptide, so “research use only” does not apply; both are prescription medicines.

Region (checked 8 Nov 2026)	Modafinil	Armodafinil
US (FDA)	Provigil, first US approval 1998; excessive sleepiness in narcolepsy, OSA, shift work disorder; Schedule IV [2]	Nuvigil, NDA 021875 approved 15 June 2007; the same three indications; Schedule IV [1][3]
EU	Narcolepsy only since the Commission decision of 27 January 2011 [4]	No entry in EMA’s central-medicines data; national status not checked [6]
UK, Germany	See the modafinil guide and legal status by country	Not checked

Both US labels say that in OSA the drug treats sleepiness, not the obstruction, and neither is approved for children [1][2].

The 2011 EMA review covered modafinil only. In November 2010 the CHMP concluded that benefits outweigh risks only in narcolepsy; for OSA, shift work disorder and idiopathic hypersomnia, trial data “did not provide strong evidence” [4]. Before the decision, modafinil was licensed in 21 European countries and narcolepsy was the only indication all of them shared [5]. The CHMP recommended maintaining the authorisations with the narrower indication; they are sold as Modasomil, Modiodal, Provigil, Vigil and generics [4][5]. The annex lists no armodafinil product.

We searched EMA’s data export (8 Nov 2026, 2,757 records, including withdrawn and refused applications) for armodafinil and Nuvigil and found nothing [6]. A commercial web page claimed a centrally authorised product was withdrawn in 2011; we found no EMA record supporting that and do not repeat it. We could not query the UK MHRA register and did not check BfArM, so national licences for armodafinil are not verified.

What do the labels say about pharmacokinetics?

	Nuvigil (armodafinil)	Provigil (modafinil)
Time to peak	About 2 hours fasted; a meal may delay it by 2-4 hours [1]	2-4 hours; a meal may delay it by about 1 hour [2]
Half-life	Apparent terminal half-life about 15 hours [1]	Effective half-life about 15 hours after repeated dosing; R-form about 3 times S-form [2]
S-form	Half-life about 4 hours [1]	10% of trough concentration; R-form is 90% [2]

The Nuvigil label calls R-enantiomer curves after a single dose of Nuvigil and twice that milligram amount of Provigil “nearly superimposable”. At steady state, equal-milligram doses gave about 37% higher peak and 70% higher total exposure with armodafinil, because the S-enantiomer clears faster [1].

The manufacturer’s clinical pharmacology group (Cephalon) published several comparisons. In a randomized open-label crossover of 42 patients with treated OSA, half-lives were 16.5 hours for armodafinil and 14.4 hours for modafinil, total exposure ratios were 1.64 (single dose) and 1.69 (repeated), and the pair failed FDA bioequivalence limits [19]. Pooled single-dose data from three studies in healthy adults found half-lives of about 13 hours for both and 33-40% higher exposure with armodafinil [20]; a steady-state analysis of 52 healthy men found late-day concentrations 44% higher [21]. These show different blood-level curves, not better outcomes.

What do the armodafinil trials show?

All four pivotal trials were 12 weeks, double-blind and placebo-controlled, with no modafinil arm. The papers’ abstracts do not state funding; ClinicalTrials.gov lists Cephalon (now part of Teva) as sponsor of the matching registrations [12][13][14][15]. Results are therefore company-funded.

Trial	Population	Size	Main result vs placebo
Harsh 2006 [8]	Narcolepsy	196	Waking-test latency +1.9 min vs -1.9 min; global improvement 71% vs 33%
Roth 2006 [9]	OSA with residual sleepiness on CPAP, 37 US and Canadian centres	395	Global improvement 72% vs 37%; Epworth score change -5.5 vs -3.3
Hirshkowitz 2007 [10]	Same population	259	Waking-test latency +2.3 min vs -1.3 min; global improvement 71% vs 53%
Czeisler 2009 [11]	Shift work disorder, 42 sites, 2004	254	Night sleep latency 2.3 to 5.3 min vs 2.4 to 2.8 min; improvement 79% vs 59%

Head-to-head trials, in patients. Tembe and colleagues randomized 211 patients with shift work sleep disorder in India to armodafinil or modafinil for 12 weeks. Responder rates were 72.1% and 74.3% (p = 0.76), adverse events were comparable, and the authors saw no efficacy or safety difference [17]. The abstract gives no funder and the full text was blocked to us, so we could not verify who paid.

A Cephalon trial registered as NCT00236080 compared Provigil, three armodafinil dose levels and placebo in 136 shift workers at 16 US centres in late 2005. Posted results show the sleep-test change was 2.0 minutes for Provigil, 2.7-3.7 for armodafinil and 1.1 for placebo (overall p = 0.12). The sponsor wrote that data-transfer errors occurred at some centres and the findings “should be considered inconclusive” [16]. We found no journal article for it; a registry-number search of PubMed returned none, which is not proof that none exists.

A Cephalon model pooled two separate shift work trials (463 patients; one per drug) and predicted a 0.5-1 minute advantage for armodafinil late in the shift [22]. That is a model, not a randomized comparison.

Pooled reviews. A 2016 meta-analysis of sleep apnea trials (11 modafinil trials, 723 patients; 5 armodafinil trials, 1,009) found similar effects against placebo: Epworth change -2.96 vs -2.63 points, waking-test gain 2.51 vs 2.71 minutes. This is an indirect comparison [23]. A 2023 network meta-analysis of 14 trials (3,085 patients, no funding) grouped the two as one class [24]. The 2026 American Academy of Sleep Medicine guideline for shift work disorder likewise suggests “armodafinil or modafinil” together (conditional, moderate certainty) [25].

Are there safety differences?

Mostly the warnings match: serious rash including Stevens-Johnson syndrome, multi-organ hypersensitivity, psychiatric symptoms, blood pressure increases, and reduced effect of hormonal contraceptives for one month after stopping [1][2]. The Nuvigil label says armodafinil has not been studied in children and cites modafinil trials for pediatric rash data [1].

Some wording differs. The Provigil label says angioedema was seen with armodafinil but not in modafinil’s trials [2]; the Nuvigil label lists angioedema and anaphylaxis as observed [1]. The Nuvigil label says physical dependence can occur with withdrawal symptoms and reports abuse patterns, while the Provigil label cites one trial without withdrawal over 14 days [1][2]. The labels do not say either drug is riskier.

Adverse-event tables come from separate trials and the labels warn against comparing them. For reference: Nuvigil headache 17% vs 9% on placebo, discontinuation for adverse reactions 7% vs 4% (645 treated) [1]; Provigil headache 34% vs 23%, discontinuation 8% vs 3% (934 treated) [2]. In the only direct tolerability data, the 211-patient trial found comparable events [17]; the 42-patient open-label crossover reported headache in 29% on armodafinil and 2% on modafinil, with small numbers and a sponsor [19].

Is there a head-to-head trial in healthy people?

We searched PubMed and ClinicalTrials.gov on 8 Nov 2026 and found none that is large. The one direct randomized comparison is Dinges 2006: 107 healthy men, a single dose and one night of sleep loss, with several armodafinil dose levels, modafinil and placebo. All active arms beat placebo, and armodafinil gave longer waking-test latency and fewer attention lapses 6-14 hours after dosing than modafinil [18]. It was one night, small groups, and the abstract does not state a funder. Other healthy-volunteer work on armodafinil that we found was pharmacokinetic [20][21]. The meta-analyses on modafinil in rested adults are summarized in our healthy adults evidence review; they do not test armodafinil.

Brand and generic status

In the US, Drugs@FDA lists Nuvigil as the reference product with AB-rated equivalents from at least Aurobindo, Macleods, Mylan and Natco [3]. DailyMed also carries armodafinil labels from Teva and Sandoz, and Nuvigil labels under Cephalon (version of 7 May 2025) and Apotex (version of 15 September 2026) [7].

Risks and unknowns

Documented risks are those above: skin and hypersensitivity reactions, psychiatric events, cardiovascular cautions, contraceptive interaction, and abuse and dependence wording [1]. Pregnancy is flagged in both labels, with reports of intrauterine growth restriction and spontaneous abortion and animal developmental toxicity [1][2]; see the modafinil guide for the human studies.

Not established: whether armodafinil’s higher late-day levels improve outcomes over modafinil; efficacy and safety in children; long-term use in healthy people; and the licensing status of armodafinil in the EU and UK.

What a source post claims

@dex7official’s cognitive-enhancement tier list (20 October 2026) puts armodafinil in tier D beside modafinil, Semax, Selank, L-theanine and alpha-GPC [26]. Verdict: could not be verified. The ranking states no criteria, and the placement comes from Peptilyze’s transcription of the image, not a reopened post. Equal placement fits the lack of evidence for a difference in healthy people, but a tier list tests nothing.

Frequently asked questions

Is armodafinil the same drug as modafinil?

It is one half of it. Modafinil is a 1:1 mix of R- and S-enantiomers; armodafinil is the R-enantiomer alone. The US labels give both the same indications [1][2].

Does armodafinil last longer?

The labels report similar half-lives of about 15 hours. Blood levels late in the day are higher with armodafinil at equal milligrams because the S-form clears faster [1][19][21]. Whether that changes outcomes is not established.

Is armodafinil approved in the EU or UK?

We could not confirm it. The 2011 EMA review and its restriction to narcolepsy concerned modafinil, and EMA’s central data export has no armodafinil entry. National registers were not checked [4][6].

Has anyone compared them directly?

Yes, in small trials: 211 shift workers in India found no difference [17], a registered company trial of 136 is flagged inconclusive by its sponsor [16], and one single-night study of 107 healthy men favoured armodafinil late after dosing [18].

Sources

1. Apotex Corp., “NUVIGIL (armodafinil) tablets, prescribing information”, DailyMed (label text revised February 2025; SPL version published 15 Sep 2026). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=a69631d0-1263-769e-b232-4ab9160e0fa3
2. Apotex Corp., “PROVIGIL (modafinil) tablets, prescribing information”, DailyMed (revised February 2025). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=0391f182-1958-9fef-a944-53b229ce99e7
3. FDA, “Drugs@FDA: NDA 021875 Nuvigil, overview” (accessed 2026-11-08). https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=021875
4. EMA, “Modafinil - referral” (CHMP opinion 18 Nov 2010, Commission decision 27 Jan 2011). https://www.ema.europa.eu/en/medicines/human/referrals/modafinil
5. EMA, “Modafinil article 31 referral: Annexes I-IV” (2011). https://www.ema.europa.eu/en/documents/referral/modafinil-article-31-referral-annex-i-ii-iii-iv_en.pdf
6. EMA, “Medicines output: medicines data (JSON report)”, 2,757 records (timestamp 2026-11-08). https://www.ema.europa.eu/en/documents/report/medicines-output-medicines_json-report_en.json
7. National Library of Medicine, “DailyMed SPL search, drug name armodafinil and nuvigil” (queried 2026-11-08). https://dailymed.nlm.nih.gov/dailymed/services/v2/spls.json?drug_name=armodafinil&pagesize=40
8. Harsh JR et al., “The efficacy and safety of armodafinil as treatment for adults with excessive sleepiness associated with narcolepsy”, Curr Med Res Opin 2006;22:761-74. https://pubmed.ncbi.nlm.nih.gov/16684437/
9. Roth T et al., “Effects of armodafinil in the treatment of residual excessive sleepiness associated with obstructive sleep apnea/hypopnea syndrome”, Clin Ther 2006;28:689-706. https://pubmed.ncbi.nlm.nih.gov/16861091/
10. Hirshkowitz M et al., “Adjunct armodafinil improves wakefulness and memory in obstructive sleep apnea/hypopnea syndrome”, Respir Med 2007;101:616-27. https://pubmed.ncbi.nlm.nih.gov/16908126/
11. Czeisler CA et al., “Armodafinil for treatment of excessive sleepiness associated with shift work disorder: a randomized controlled study”, Mayo Clin Proc 2009;84:958-72. https://pubmed.ncbi.nlm.nih.gov/19880686/
12. ClinicalTrials.gov, NCT00078377, armodafinil in narcolepsy (sponsor Cephalon, 196 participants). https://clinicaltrials.gov/study/NCT00078377
13. ClinicalTrials.gov, NCT00078325, armodafinil in OSA (sponsor Cephalon, 395 participants). https://clinicaltrials.gov/study/NCT00078325
14. ClinicalTrials.gov, NCT00079677, armodafinil in OSA (sponsor Cephalon, 263 participants). https://clinicaltrials.gov/study/NCT00079677
15. ClinicalTrials.gov, NCT00080288, armodafinil in shift work sleep disorder (sponsor Cephalon, 254 participants; record verified 2013-07). https://clinicaltrials.gov/study/NCT00080288
16. ClinicalTrials.gov, NCT00236080, armodafinil and PROVIGIL in chronic shift work sleep disorder, with posted results (sponsor Cephalon, 136 participants). https://clinicaltrials.gov/study/NCT00236080
17. Tembe DV et al., “Armodafinil versus modafinil in patients of excessive sleepiness associated with shift work sleep disorder”, Neurol Res Int 2011;2011:514351 (abstract read; full text blocked). https://pubmed.ncbi.nlm.nih.gov/21766023/
18. Dinges DF et al., “Pharmacodynamic effects on alertness of single doses of armodafinil in healthy subjects during a nocturnal period of acute sleep loss”, Curr Med Res Opin 2006;22:159-67 (abstract read). https://pubmed.ncbi.nlm.nih.gov/16393442/
19. Darwish M et al., “Pharmacokinetics of armodafinil and modafinil after single and multiple doses in patients with excessive sleepiness associated with treated obstructive sleep apnea”, Clin Ther 2010;32:2074-87. https://pubmed.ncbi.nlm.nih.gov/21118743/
20. Darwish M et al., “Armodafinil and modafinil have substantially different pharmacokinetic profiles despite having the same terminal half-lives”, Clin Drug Investig 2009;29:613-23. https://pubmed.ncbi.nlm.nih.gov/19663523/
21. Darwish M et al., “Comparison of steady-state plasma concentrations of armodafinil and modafinil late in the day following morning administration”, Clin Drug Investig 2009;29:601-12. https://pubmed.ncbi.nlm.nih.gov/19663522/
22. Darwish M et al., “Armodafinil and modafinil in patients with excessive sleepiness associated with shift work disorder: a pharmacokinetic/pharmacodynamic model”, J Clin Pharmacol 2012;52:1328-42. https://pubmed.ncbi.nlm.nih.gov/22039290/
23. Kuan YC et al., “Effects of modafinil and armodafinil in patients with obstructive sleep apnea: a meta-analysis of randomized controlled trials”, Clin Ther 2016;38:874-88. https://pubmed.ncbi.nlm.nih.gov/26923035/
24. Pitre T et al., “Comparative efficacy and safety of wakefulness-promoting agents for excessive daytime sleepiness in patients with obstructive sleep apnea: a systematic review and network meta-analysis”, Ann Intern Med 2023;176:676-84. https://pubmed.ncbi.nlm.nih.gov/37155992/
25. Wright KP Jr et al., “Management of shift work disorder: an American Academy of Sleep Medicine clinical practice guideline”, J Clin Sleep Med 2026;22. https://pubmed.ncbi.nlm.nih.gov/42925456/
26. @dex7official, “THE ONLY TRUE COGNITIVE ENHANCEMENT TIER LIST (NO COPES EDITION)” (20 Oct 2026). https://x.com/dex7official/status/2112691493261484516 (not reopened; placement read from the image by Peptilyze). A claim, not evidence.

This article is information, not medical advice.