Clinical data
Routes of
ATC code
  • none
Pharmacokinetic data
Elimination half-life1.5–1.8 hours
  • N-methyl-N-[3-[3-(thiophene-2-carbonyl)
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.133.676 Edit this at Wikidata
Chemical and physical data
Molar mass376.43 g·mol−1
3D model (JSmol)
  • O=C(C1=CC=CS1)C2=C3N=CC=C(C4=CC(N(C)C(C)=O)=CC=C4)N3N=C2
  • InChI=1S/C20H16N4O2S/c1-13(25)23(2)15-6-3-5-14(11-15)17-8-9-21-20-16(12-22-24(17)20)19(26)18-7-4-10-27-18/h3-12H,1-2H3 checkY
 ☒NcheckY (what is this?)  (verify)

Indiplon (INN and USAN) is a nonbenzodiazepine, hypnotic sedative that was developed in two formulations—an immediate-release formulation for sleep onset, and a modified-release (also called controlled-release or extended-release) version for sleep maintenance.



Indiplon works by enhancing the action of the inhibitory neurotransmitter GABA, like most other nonbenzodiazepine sedatives. It primarily binds to the α1 subunits of the GABAA receptors in the brain.[1]


Indiplon has a short elimination half-life of 1.5 to 1.8 hours in young and elderly subjects, respectively.[2]


Indiplon was discovered at Lederle Laboratories (which was later acquired by Wyeth) in the 1980s and was called CL 285,489.[3]: 454  In 1998 Lederle licensed it, along with other early stage drug candidates, to DOV Pharmaceutical, a startup formed by former Lederle employees, and Dov exclusively sublicensed its rights in the drug to Neurocrine Biosciences in that same year.[3] In 2002, Neurocrine entered into an agreement with Pfizer to develop the drug.[3]

Indiplon was originally scheduled for release in 2007, when Sanofi-Aventis' popular hypnotic zolpidem lost its patent rights in the United States and thus became available as a much less expensive generic. In 2002, Neurocrine Biosciences had entered into an agreement with Pfizer to co-market indiplon in the US, in a deal worth a potential $400mn.[4] However, following the issuing of a non-approvable letter for the modified-release 15 mg formulation and an approvable letter with stipulations for the 5 mg and 10 mg immediate-release version by the FDA in May 2006,[5] Pfizer ended its relationship with Neurocrine.[6] Neurocrine's stock price dropped 60% on the news.[7]

Following a resubmission, the FDA in December 2007 deemed Neurocrine's new drug application (NDA) 'approvable' in the 5 and 10 mg formulations,[8] but requested new studies as a prerequisite to approval, including a clinical trial in the elderly, a safety study comparing adverse effects to those of similarly marketed drugs, and a preclinical study examining indiplon's safety in the third trimester of pregnancy.[9]

Following the 2007 FDA letter, Neurocrine decided to discontinue all clinical and marketing development of Indiplon in the United States.[8][9]


  1. ^ Petroski RE, Pomeroy JE, Das R, Bowman H, Yang W, Chen AP, Foster AC (April 2006). "Indiplon is a high-affinity positive allosteric modulator with selectivity for alpha1 subunit-containing GABAA receptors" (PDF). The Journal of Pharmacology and Experimental Therapeutics. 317 (1): 369–77. doi:10.1124/jpet.105.096701. PMID 16399882. S2CID 46510829.
  2. ^ Lemon MD, Strain JD, Hegg AM, Farver DK (September 2009). "Indiplon in the management of insomnia". Drug Design, Development and Therapy. 3: 131–142. doi:10.2147/dddt.s3207. PMC 2769245. PMID 19920929.
  3. ^ a b c Neubauer DN (2010). "Indiplon". In Monti JS, Pandi-Perumal SR, Möhler H (eds.). GABA and Sleep: Molecular, Functional and Clinical Aspects. Springer Science & Business Media. pp. 453–464. ISBN 9783034602266.
  4. ^ "San Diego's Neurocrine Biosciences Scores Second Big Deal in Two Days". The Motley Fool. 18 June 2010.
  5. ^ "Neurocrine's FDA Nightmare". 16 May 2006.
  6. ^ "Pfizer Drops Neurocrine Deal". 22 June 2006.
  7. ^ "Neurocrine stock price plunges 60 percent:FDA's mixed review of sleeping pill Indiplon could threaten Pfizer-Neurocrine partnership". CNN Money. 15 May 2006.
  8. ^ a b "Neurocrine Receives Approvable Letter for Indiplon Capsules with Additional Safety and Efficacy Data Required by FDA" (Press release). Neurocrine Biosciences, Inc. 2007-12-13. Retrieved 2007-12-13.
  9. ^ a b "Additional Pipeline Projects". Neurocrine. 2012-02-16. Archived from the original on 2012-03-27. Retrieved 2014-06-24.