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danavorexton (TAK-925); the first-in-class, injectable OX2R-selective orexin agonist that proved wakefulness can be pharmacologically restored, now aimed at reversing anesthetic and opioid sedation.
- first drug to prove OX2R agonism is druggable; directly replaces the orexin signal missing in narcolepsy type 1
- very selective (>5,000-fold OX2R over OX1R) and potent (EC50 ~5.5 nM)
- strong, cross-species wake promotion; improved objective wakefulness and cut microsleeps in narcolepsy patients
- reverses opioid- and anesthesia-induced respiratory depression and sedation without blunting pain relief
- cryo-EM-defined mechanism that guided the whole next generation of orexin agonists
Overview
the original OX2R agonist; potent, ultra-selective, and the first to prove orexin agonism works in humans, but injectable-only, so it became a perioperative 'arousal' agent while the oral successors carried narcolepsy forward.
- for years scientists thought the orexin receptor was 'undruggable' for agonists; TAK-925's cryo-EM structure showed exactly how to flip it on.
- it binds the very same pocket that insomnia drugs like suvorexant block, but pushes the receptor the opposite way.
- it can help someone breathe better after opioids without reducing the opioid's pain relief.
- it does not work as a pill, which is the entire reason TAK-861 (oveporexton) exists.
Mechanism
TAK-925, generic name danavorexton, is a small-molecule selective of receptor 2 (OX2R). the orexin () neuropeptides made in the lateral stabilize wakefulness by acting on OX1R and OX2R; narcolepsy type 1 results from the selective death of these orexin neurons, and knockout work has long shown OX2R is the receptor most tied to the sleep/wake phenotype.
TAK-925 restores that signal from downstream: according to PubMed it activates the human OX2R with an EC50 of about 5.5 nM and shows greater than 5,000-fold selectivity over OX1R (Yukitake et al., 2019, Pharmacol Biochem Behav, https://doi.org/10.1016/j.pbb.2019.172794). functionally it drives wakefulness across species; in mice, narcolepsy-model mice, marmosets and cynomolgus monkeys, and in healthy sleep-deprived humans, and in a phase 1b crossover it improved the Maintenance of Wakefulness Test and reduced microsleeps in narcolepsy type 1 and type 2 patients (Evans et al., 2023, J Sleep Res, https://doi.org/10.1111/jsr.13878; https://doi.org/10.1093/sleep/zsae148). structurally, cryo-EM of OX2R-G-protein complexes showed TAK-925 sits in the same orthosteric pocket that antagonists occupy but makes additional transmembrane contacts that trigger the receptor's activating microswitches, which is what makes agonism (long thought undruggable at this receptor) possible and selective (Rappas et al., 2022, Nat Commun, https://doi.org/10.1038/s41467-022-30601-3). beyond arousal, OX2R activation stimulates respiratory circuits (pre-Botzinger complex inspiratory neurons and phrenic/hypoglossal motoneurons), which underpins its second use case: in healthy men under remifentanil, danavorexton reduced opioid-induced respiratory depression and sedation without reducing analgesia (Yamamoto et al., 2025, Anesthesiology, https://doi.org/10.1097/ALN.0000000000005375). the practical catch is pharmacokinetic, not pharmacodynamic: TAK-925 is not orally bioavailable and must be given IV or subcutaneously, so Takeda advanced oral successors (TAK-994, then TAK-861) for chronic narcolepsy while danavorexton itself is explored for acute perioperative 'arousal' indications.
receptor fingerprint
receptor 2 (OX2R / HCRTR2)selective agonist; activates OX2R with an EC50 near 5.5 nM at the human receptor
pre-Botzinger complex inspiratory neurons / phrenic + hypoglossal motoneurons (downstream)OX2R activation stimulates respiratory drive and upper-airway muscle tone
receptor 1 (OX1R / HCRTR1)little to no activity; more than 5,000-fold selectivity for OX2R over OX1R
Dosingtypical ranges, not medical advice
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Safetyrisks and cautions, not medical advice
danavorexton has only been given in controlled trial settings and by injection, so the community safety database is small. reported use has been short-term. because it is a potent arousal agent, wakefulness-related and cardiovascular/autonomic effects are the expected watch-items; the perioperative studies were specifically designed around monitoring. it is not orally active and is not a consumer product; there is no legitimate way to obtain or self-administer it.
History
TAK-925 was Takeda's first clinical orexin agonist and the compound that broke the long-standing belief that agonizing the orexin receptor was not feasible with a small molecule. after preclinical proof of robust OX2R-selective wake promotion (2019) and early human work, cryo-EM structures in 2022 explained its selective activation mechanism. because it could not be dosed orally, Takeda pivoted the chronic-narcolepsy effort to the oral agonists TAK-994 and TAK-861, while danavorexton was repositioned toward acute in-hospital arousal (post-anesthetic recovery, opioid-induced respiratory depression).
Reputation
in sleep medicine TAK-925/danavorexton is remembered as the landmark proof-of-concept for orexin-replacement therapy; the drug that showed you can pharmacologically turn wakefulness back on at OX2R. its limitation (injection-only) is equally well known, which is why the excitement long ago shifted to its oral descendant oveporexton (TAK-861).
Subjective profileweighing the evidence above
Genuinely important pharmacology: it proved orexin-2 agonism is druggable and it reverses opioid and anaesthetic sedation without blunting pain relief. It is also an intravenous infusion given only in trials, not orally active, with no legitimate way to obtain it. Something to watch, not to take.
Resources
This entry is here for reference.
Research
- 2019first citedTAK-925, an orexin 2 receptor-selective agonist, shows robust wake-promoting effects in mice
- 2024most active year3 papers
- 2025most recentTAK-925 (Danavorexton), an Orexin Receptor 2 Agonist, Reduces Opioid-induced Respiratory Depres…
- 1.TAK-925, an orexin 2 receptor-selective agonist, shows robust wake-promoting effects in mice
- 2.Orexin 2 receptor-selective agonist danavorexton (TAK-925) promotes wakefulness in non-human primates and healthy individuals
- 3.Molecular mechanism of the wake-promoting agent TAK-925.
- 4.TAK-925 (Danavorexton), an Orexin Receptor 2 Agonist, Reduces Opioid-induced Respiratory Depression and Sedation without Affecting Analgesia in Healthy Men.
- 5.Danavorexton (TAK-925): an orexin receptor 2 agonist as a new 'arousal' agent.
- 6.Novel biomarkers derived from the Maintenance of Wakefulness Test as predictors of sleepiness and response to treatment.
- 7.Orexin receptor 2 agonist activates diaphragm and genioglossus muscle through stimulating inspiratory neurons in the pre-Bötzinger complex, and phrenic and hypoglossal motoneurons in rodents.
7 listed here; entry last updated August 2026
Reviews
My notesprivate to this device
FAQ
what is TAK-925 (danavorexton)?
it is a first-in-class orexin receptor 2 (OX2R) agonist from Takeda; essentially a wake-promoting drug that replaces the missing orexin signal. narcolepsy type 1 is caused by loss of the brain's orexin neurons, and TAK-925 directly turns the downstream OX2R back on. according to PubMed it activates the human OX2R with an EC50 around 5.5 nM and is over 5,000-fold selective for OX2R over OX1R (Yukitake et al., 2019, Pharmacol Biochem Behav, https://doi.org/10.1016/j.pbb.2019.172794).
can you take it as a pill?
no, and that is its main limitation. TAK-925 has poor oral bioavailability, so it was only ever given intravenously or subcutaneously. that is exactly why Takeda went on to build the oral OX2R agonists TAK-994 and then TAK-861; TAK-925/danavorexton itself got repositioned toward short-term, in-hospital uses like reversing sedation.
does it actually keep people awake?
yes, robustly. it promoted wakefulness in wild-type mice, narcolepsy-model mice, monkeys, and healthy sleep-deprived humans, and in a phase 1b study it improved objective wakefulness (Maintenance of Wakefulness Test) and cut microsleeps in people with narcolepsy type 1 and type 2 (Evans et al., 2023, J Sleep Res, https://doi.org/10.1111/jsr.13878; and MWT-biomarker analysis, https://doi.org/10.1093/sleep/zsae148).
why is it interesting for anesthesia and opioids?
because orexin also drives breathing and arousal. in healthy men under a remifentanil (opioid) infusion, danavorexton reduced opioid-induced respiratory depression and sedation without blunting the pain relief (Yamamoto et al., 2025, Anesthesiology, https://doi.org/10.1097/ALN.0000000000005375). that raises the idea of an 'arousal agent' to help patients recover from anesthesia or opioid oversedation (Dahan, 2024, Br J Anaesth, editorial, https://doi.org/10.1016/j.bja.2023.12.008).
how does it switch the receptor on when antagonists switch it off?
cryo-EM structures showed TAK-925 binds the same pocket that insomnia drugs (orexin antagonists) occupy, but instead of jamming the receptor it makes extra contacts with the transmembrane helices that flip the internal 'microswitches' into the active state (Rappas/Hong et al., 2022, Nat Commun, https://doi.org/10.1038/s41467-022-30601-3). that structural work basically proved OX2R agonism was druggable after years of it being considered impossible.
is it a nootropic or a stimulant i can buy?
no. it is an injectable investigational drug studied in trials, not a consumer product, and it does not work orally anyway. its relevance to the wider nootropics conversation is conceptual: it is proof that you can pharmacologically restore orexin signaling, which is the deficit at the root of narcolepsy.
is it the same as suvorexant or lemborexant?
it is the mirror image. suvorexant, lemborexant and seltorexant are orexin receptor antagonists used to cause sleep; TAK-925/danavorexton is an orexin receptor agonist used to cause wakefulness. same receptor system, opposite direction.
what is its development status?
TAK-925 itself was not taken forward as a chronic oral narcolepsy therapy because it is not orally viable; Takeda advanced the oral successors instead. danavorexton has continued to be explored for acute, in-hospital arousal indications (post-anesthesia and opioid-induced respiratory depression), where an intravenous agent is acceptable.