Clinical data
Trade namesCylert, others
Other namesPheniminooxazolidinone; Phenylisohydantoin; Phenylpseudohydantoin; Phenilone; 2-Imino-5-phenyl-4-oxazolidinone; 2-Amino-5-phenyl-1,3-oxazol-4(5H)-one
AHFS/Drugs.comMicromedex Detailed Consumer Information
Routes of
ATC code
Legal status
Legal status
Pharmacokinetic data
Protein binding≤50%[2][1]
Elimination half-life7–12 hours[1][2]
ExcretionMainly urine[2]
  • (RS)-2-amino-5-phenyl-1,3-oxazol-4(5H)-one
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.016.763 Edit this at Wikidata
Chemical and physical data
Molar mass176.175 g·mol−1
3D model (JSmol)
ChiralityRacemic mixture
  • O=C2\N=C(/OC2c1ccccc1)N
  • InChI=1S/C9H8N2O2/c10-9-11-8(12)7(13-9)6-4-2-1-3-5-6/h1-5,7H,(H2,10,11,12) checkY
 ☒NcheckY (what is this?)  (verify)

Pemoline, sold under the brand name Cylert among others, is a stimulant medication which has been used in the treatment of attention-deficit hyperactivity disorder (ADHD) and narcolepsy.[2] It has been discontinued in most countries due to rare but serious problems with liver toxicity.[4][5] The medication was taken by mouth.[2]

Side effects of pemoline include insomnia, decreased appetite, abdominal pain, irritability, and headaches.[1][2] Rarely, the medication can cause serious liver damage, and this can result in liver transplantation or death.[6][7] Pemoline is a psychostimulant and acts as a selective dopamine reuptake inhibitor and releasing agent.[1][8][2] Hence, it functions as an indirect agonist of dopamine receptors.[9] Pemoline has little effect on norepinephrine and hence has minimal or no cardiovascular or sympathomimetic effects, in contrast to many other stimulants.[1][8][2]

Pemoline was synthesized in 1913 but was not discovered to be a stimulant until the 1930s and was not used in the treatment of ADHD until 1975.[10][11][1] It was withdrawn due to liver toxicity in many countries between 1997 and 2005, including the United States.[12][7][13] However, it remains available in Japan for the treatment of narcolepsy at lower doses than used for ADHD.[5] Pemoline is a schedule IV controlled substance in the United States due to its relation to other stimulants and a potential for misuse.[14][15] It seems to have less misuse potential than other stimulants.[1]

Medical uses

Pemoline has been used in the treatment of ADHD and narcolepsy.[2][1][5] It has also been used in the treatment of excessive daytime sleepiness.[8] The medication was typically used at doses of 18.75 to 112.5 mg once per day in the treatment of ADHD, with the effective dose for most people being in the range of 56.25 to 75 mg.[1][2] The onset of action of pemoline is gradual and therapeutic benefits may not occur until the third or fourth weeks of use.[2][1] This may be due to a cautious low initial starting dose of 37.5 mg and gradual titration in dose upwards over several weeks.[1]

Available forms

Pemoline was available in the form of 18.75, 37.5, and 75 mg oral immediate-release tablets (Cylert) as well as 37.5 mg oral immediate-release chewable tablets.[1][2] It was provided mainly in the form of the free base but also as the magnesium salt.[16]

Side effects

Side effects of pemoline include insomnia, decreased appetite, abdominal pain, irritability, and headaches.[1][2] It has minimal cardiovascular or sympathomimetic side effects.[1][2] Pemoline is described as a lower-efficacy/milder stimulant than classical stimulants like amphetamines and methylphenidate and is said to have fewer side effects than them.[17]

Liver toxicity

Rarely, pemoline is implicated in causing hepatotoxicity.[1][18] Because of this, the FDA recommended that regular liver tests be performed in those treated with it.[19] Since being introduced, it has been linked with at least 21 cases of liver failure, of which 13 resulted in liver replacement or death. Approximately 1–2% of patients taking the drug show elevated levels of liver transaminase enzymes, a marker for liver toxicity, though serious cases are rare. Over 200,000 children with ADHD were prescribed pemoline in the United States and Canada alone during the approximate 25 years that it was available, plus a smaller number of adults prescribed it for other indications (and not including prescriptions in the rest of the world). As such, the number of liver failure cases was statistically not that large. However the reactions proved idiosyncratic and unpredictable, with patients sometimes taking the drug with no issue for months or even years, before suddenly developing severe liver toxicity. There was no clear exposure–toxicity relationship, and no characteristic liver pathology findings. Some patients showed as little as one week between first appearance of jaundice and complete liver failure, and some of the patients that developed liver failure had not showed elevated liver transaminase levels when tested previously.[13] On the other hand, there are no cases of liver failure associated with pemoline in Japan, although it is used at lower doses and is only prescribed for the niche indication of narcolepsy in this country.[5]


Overdose of pemoline may present with choreoathetosis symptoms.[20]


Other stimulants and monoamine oxidase inhibitors are contraindicated with pemoline.



The pharmacodynamics of pemoline are poorly understood and its precise mechanism of action hasn't been definitively determined.[1][2] However, pemoline has similar activity and effects to those of other psychostimulants, and in animals the medication appears to act as a dopamine reuptake inhibitor and releasing agent.[1] By increasing dopamine levels in the brain, it functions as an indirect agonist of dopamine receptors.[9] In contrast to most other stimulants, pemoline appears to produce no significant central or peripheral noradrenergic effects.[1] As a result, it has minimal or no cardiovascular or sympathomimetic effects.[1] Pemoline is described as a selective dopamine reuptake inhibitor that only weakly stimulates dopamine release.[8]

While drugs like dextroamphetamine and methylphenidate are classified as schedule II and have considerable misuse potential, pemoline is listed as schedule IV (non-narcotic).[2] In studies conducted on primates, pemoline fails to demonstrate a potential for self-administration.[2] It is thought to have little potential for abuse and dependence.[1] Nonetheless, misuse may theoretically occur owing to its similarity to other psychostimulants.[2]


Studies of the pharmacokinetics of pemoline in humans are very limited.[1] The time to peak levels of pemoline is 2 to 4 hours.[2][1] Peak levels have been reported to be in the range of 2 to 4.5 μg/mL.[1] Steady-state levels of pemoline are reached in 2 to 3 days.[2]

Pemoline is variously reported to have no significant plasma protein binding or to have 50% plasma protein binding.[1][2]

Pemoline is metabolized in the liver.[2] Its metabolites include pemoline conjugate, pemoline dione, mandelic acid, and unidentified polar metabolites.[2]

Pemoline is excreted mainly by the kidneys with around 50% excreted in unchanged form and only minor amounts present as metabolites.[2] The elimination half-life of pemoline is 7 to 12 hours.[1][2] The half-life is 7 hours in children but may increase to 11 to 12 hours with age.[1] The relatively long half-life of pemoline allows for once-daily administration.[1]

No differences in the pharmacokinetics of pemoline were found with conventional tablets, chewable tablets swallowed, or chewable tablets chewed.[1]


Pemoline is a member of the 4-oxazolidinone class and is structurally related to other members of the class including aminorex, 4-methylaminorex, clominorex, cyclazodone, fenozolone, fluminorex, and thozalinone.

The salts of pemoline in use are pemoline magnesium (free base conversion ratio .751), pemoline iron (.578), pemoline copper (.644), pemoline nickel (.578), pemoline rubidium, pemoline calcium, pemoline chromium, and chelates of the above which are identical in weight to the salt mentioned. Pemoline free base and pemoline cobalt, strontium, silver, barium, lithium, sodium, potassium, zinc, manganese, and caesium are research chemicals which can be produced in situ for experiments.[15][21][22] Others such as lanthanide pemoline salts such as pemoline cerium can be prepared; pemoline beryllium would presumably be toxic.


Pemoline was first synthesized in 1913[23][10] but its activity was not discovered until the 1930s.[11] Pemoline was approved for the treatment of ADHD in the United States in 1975.[1][5]

Cases of serious liver toxicity and associated death related to pemoline in children and adolescents were reported to the United States Food and Drug Administration's MedWatch between 1977 and 1996.[7] Serious liver toxicity with pemoline was first described in the medical literature in 1984 and 1989 letters to the editor.[7] Clinicians were little-aware of liver toxicity with pemoline until the 1990s.[7] Warnings for liver toxicity for pemoline were added to the United States Food and Drug Administration (FDA) label for the medication in December 1996 and a black box warning was added in June 1999 along with requirements for written consent and frequent monitoring of liver enzymes.[12][13][7] These warnings followed a 1995 publication on liver toxicity with pemoline.[7][24] However, findings suggested that clinicians poorly followed the FDA's directives on use of pemoline.[12] In any case, sales of pemoline in the United States increased until 1997 and declined between 1996 and 1999.[7] Pemoline was withdrawn due to liver toxicity in the United Kingdom in September 1997, in Canada in September 1999, and in the United States in 2005.[12][25][13][7] Abbott Laboratories voluntarily withdrew pemoline from the United States market in May 2005 and the FDA withdrew approval of generic pemoline in November 2005.[12][13] Pemoline remains available in Japan for treatment of narcolepsy as of 2017.[5]

Society and culture


Pemoline is the generic name of the drug and its INNTooltip International Nonproprietary Name, USANTooltip United States Adopted Name, and BANTooltip British Approved Name.[23][16]

Pemoline was formerly marketed under the brand names Cylert, Betanamin, Ceractiv, Hyperilex, Kethamed, Ronyl, Stimul, Tamilan, Tradon, Tropocer, and Volital.[16][26][23]


Pemoline has been marketed in the United States, Canada, the United Kingdom, Belgium, Luxembourg, Spain, Germany, Switzerland, Japan and Argentina.[16] It remains available in Japan for the treatment of narcolepsy as of 2017.[5] However, the medication is said to be rarely used in Japan as narcolepsy is a niche indication and as clinicians are wary of the liver toxicity that it has been associated with.[5][27]

Legal status

Under the Convention on Psychotropic Substances, it is a schedule IV controlled substance.[14] Pemoline is Schedule IV Non-Narcotic (Stimulant) controlled substance with a DEA ACSCN of 1530 and is not subject to annual manufacturing quotas.[15]



Pemoline has been studied in and reported to be effective in the treatment of fatigue due to multiple sclerosis and HIV-related disease.[28]


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  2. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab "Cylert (Pemoline)" (PDF). FDA. December 2002. Archived (PDF) from the original on 4 March 2016. Retrieved 15 February 2014.
  3. ^ Anvisa (2023-03-31). "RDC Nº 784 - Listas de Substâncias Entorpecentes, Psicotrópicas, Precursoras e Outras sob Controle Especial" [Collegiate Board Resolution No. 784 - Lists of Narcotic, Psychotropic, Precursor, and Other Substances under Special Control] (in Brazilian Portuguese). Diário Oficial da União (published 2023-04-04). Archived from the original on 2023-08-03. Retrieved 2023-08-16.
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  6. ^ Nakamura H, Blumer JL, Reed MD (March 2002). "Pemoline ingestion in children: a report of five cases and review of the literature". J Clin Pharmacol. 42 (3): 275–82. doi:10.1177/00912700222011292. PMID 11865963. S2CID 27024140.
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  10. ^ a b Chemische Berichte, 1913, vol.46, p. 2083
  11. ^ a b Acta Academiae Aboensis, Series B: Mathematica et Physica, 1939, vol. 11, #14 p. 3,7
  12. ^ a b c d e Zito JM, Derivan AT, Kratochvil CJ, Safer DJ, Fegert JM, Greenhill LL (September 2008). "Off-label psychopharmacologic prescribing for children: history supports close clinical monitoring". Child Adolesc Psychiatry Ment Health. 2 (1): 24. doi:10.1186/1753-2000-2-24. PMC 2566553. PMID 18793403.
  13. ^ a b c d e Etwel FA, Rieder MJ, Bend JR, Koren G (2008). "A surveillance method for the early identification of idiosyncratic adverse drug reactions". Drug Saf. 31 (2): 169–80. doi:10.2165/00002018-200831020-00006. PMID 18217792. S2CID 19964105.
  14. ^ a b "List of psychotropic substances under international control" (PDF) (23rd ed.). Viennam, Austria: International Narcotics Control Board. August 2003. Archived from the original (PDF) on 5 December 2005. Annual Estimates Of Requirements Of Narcotic Drugs, Manufacture Of Synthetic Drugs, Opium Production And Cultivation
  15. ^ a b c DEA office of Diversion Control site: Federal Register publications of CSA schedules, 2014 Q1
  16. ^ a b c d Swiss Pharmaceutical Society (2000). Swiss Pharmaceutical Society (ed.). Index Nominum 2000: International Drug Directory. Taylor & Francis. pp. 799–. ISBN 978-3-88763-075-1.
  17. ^ Nishino S, Kotorii N (2016). "Overview of Management of Narcolepsy". Narcolepsy. Springer International Publishing. pp. 285–305. doi:10.1007/978-3-319-23739-8_21. ISBN 978-3-319-23738-1.
  18. ^ Marotta PJ, Roberts EA (May 1998). "Pemoline hepatotoxicity in children". J. Pediatr. 132 (5): 894–7. doi:10.1016/S0022-3476(98)70329-4. PMID 9602211.
  19. ^ Willy ME, Manda B, Shatin D, Drinkard CR, Graham DJ (July 2002). "A study of compliance with FDA recommendations for pemoline (Cylert)". J Am Acad Child Adolesc Psychiatry. 41 (7): 785–90. doi:10.1097/00004583-200207000-00009. PMID 12108802. Archived from the original on 2021-05-31. Retrieved 2020-09-10.
  20. ^ Stork CM, Cantor R (1997). "Pemoline induced acute choreoathetosis: case report and review of the literature". J. Toxicol. Clin. Toxicol. 35 (1): 105–8. doi:10.3109/15563659709001175. PMID 9022662.
  21. ^ The A-Z Encyclopaedia of Alcohol and Drug Abuse
  22. ^ CRC Handbook of Chemistry & Physics
  23. ^ a b c Elks J, ed. (14 November 2014). The Dictionary of Drugs: Chemical Data: Chemical Data, Structures and Bibliographies. Springer. pp. 70–. ISBN 978-1-4757-2085-3. OCLC 1058412474.
  24. ^ Berkovitch M, Pope E, Phillips J, Koren G (June 1995). "Pemoline-associated fulminant liver failure: testing the evidence for causation". Clin Pharmacol Ther. 57 (6): 696–8. doi:10.1016/0009-9236(95)90233-3. PMID 7781270. S2CID 37312352.
  25. ^ Shah RR (September 2006). "Can pharmacogenetics help rescue drugs withdrawn from the market?". Pharmacogenomics. 7 (6): 889–908. doi:10.2217/14622416.7.6.889. PMID 16981848.
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  27. ^ Takeda T (March 2009). "Psychopharmacology for attention-deficit/hyperactivity disorder in Japan". Current Attention Disorders Reports. 1 (1): 21–28. doi:10.1007/s12618-009-0004-5. eISSN 1943-457X. ISSN 1943-4561. S2CID 3559647.
  28. ^ Kaminski M, Sjøgren P (2007-02-22). "The use of psychostimulants in palliative and supportive treatment of cancer patients". Advances in Palliative Medicine (in Polish). 6 (1): 23–32. ISSN 1898-3863. Retrieved 2022-05-09.