Phenytoin

Phenytoin
Structural formula of phenytoin
Ball-and-stick model of the phenytoin molecule
Clinical data
Pronunciation/fəˈnɪtɪn, ˈfɛnɪtɔɪn/
Trade namesDilantin, others[1]
AHFS/Drugs.comMonograph
MedlinePlusa682022
License data
Pregnancy
category
  • AU: D
  • Toxic to reproduction
Routes of
administration
By mouth, intravenous
Drug classAnticonvulsant
ATC code
Legal status
Legal status
Pharmacokinetic data
Bioavailability70–100% (oral), 24.4% (rectal)
Protein binding95%[3]
MetabolismLiver
Onset of action10–30 min (intravenous)[4]
Elimination half-life10–22 hours[3]
Duration of action24 hours[4]
ExcretionUrinary (23–70%), bile[5]
Identifiers
  • 5,5-diphenylimidazolidine-2,4-dione
CAS Number
PubChem CID
IUPHAR/BPS
DrugBank
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
CompTox Dashboard (EPA)
ECHA InfoCard100.000.298 Edit this at Wikidata
Chemical and physical data
FormulaC15H12N2O2
Molar mass252.273 g·mol−1
3D model (JSmol)
  • C1=CC=C(C=C1)C2(C(=O)NC(=O)N2)C3=CC=CC=C3
  • InChI=1S/C15H12N2O2/c18-13-15(17-14(19)16-13,11-7-3-1-4-8-11)12-9-5-2-6-10-12/h1-10H,(H2,16,17,18,19) ☒N
  • Key:CXOFVDLJLONNDW-UHFFFAOYSA-N ☒N
 ☒NcheckY (what is this?)  (verify)

Phenytoin (PHT), sold under the brand name Dilantin among others,[1] is an anti-seizure medication.[3] It is useful for the prevention of tonic-clonic seizures (also known as grand mal seizures) and focal seizures, but not absence seizures.[3] The intravenous form, fosphenytoin, is used for status epilepticus that does not improve with benzodiazepines.[3] It may also be used for certain heart arrhythmias or neuropathic pain.[3] It can be taken intravenously or by mouth.[3] The intravenous form generally begins working within 30 minutes and is effective for roughly 24 hours.[4] Blood levels can be measured to determine the proper dose.[3]

Common side effects include nausea, stomach pain, loss of appetite, poor coordination, increased hair growth, and enlargement of the gums.[3] Potentially serious side effects include sleepiness, self harm, liver problems, bone marrow suppression, low blood pressure, and toxic epidermal necrolysis.[3] There is evidence that use during pregnancy results in abnormalities in the baby.[3] It appears to be safe to use when breastfeeding.[3] Alcohol may interfere with the medication's effects.[3]

Phenytoin was first made in 1908 by the German chemist Heinrich Biltz and found useful for seizures in 1936.[6][7] It is on the World Health Organization's List of Essential Medicines.[8] Phenytoin is available as a generic medication.[9] In 2020, it was the 260th most commonly prescribed medication in the United States, with more than 1 million prescriptions.[10][11]

  1. ^ a b Cite error: The named reference genericnames was invoked but never defined (see the help page).
  2. ^ Anvisa (31 March 2023). "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 4 April 2023). Archived from the original on 3 August 2023. Retrieved 16 August 2023.
  3. ^ a b c d e f g h i j k l m "Phenytoin". The American Society of Health-System Pharmacists. Archived from the original on 8 September 2015. Retrieved 22 August 2015.
  4. ^ a b c Marx JA (2010). Rosen's emergency medicine: concepts and clinical practice (7th ed.). Philadelphia: Mosby/Elsevier. p. 1352. ISBN 9780323054720.
  5. ^ Parker KD, Elliott HW, Wright JA, Nomof N, Hine CH (March 1970). "Blood and urine concentrations of subjects receiving barbiturates, meprobamate, glutethimide, or diphenylhydantoin". Clinical Toxicology. 3 (1). Informa UK Limited: 131–145. doi:10.3109/15563657008990108. PMID 5520387.
  6. ^ Aicardi J (2008). Epilepsy : a comprehensive textbook (2nd ed.). Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. p. 1431. ISBN 9780781757775.
  7. ^ Wolfson AB (2010). Harwood-Nuss' clinical practice of emergency medicine (5th ed.). Philadelphia, PA: Lippincott Williams & Wilkins. p. 1415. ISBN 9780781789431. Retrieved 9 June 2016.
  8. ^ World Health Organization (2019). World Health Organization model list of essential medicines: 21st list 2019. Geneva: World Health Organization. hdl:10665/325771. WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO.
  9. ^ Hamilton RJ (2013). Tarascon pocket pharmacopoeia (14 ed.). Burlington, MA.: Jones & Bartlett Learning. p. 294. ISBN 9781449673635.
  10. ^ "The Top 300 of 2020". ClinCalc. Retrieved 7 October 2022.
  11. ^ "Phenytoin - Drug Usage Statistics". ClinCalc. Retrieved 7 October 2022.

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