U.S. Department of Health & Human Services Divider Arrow National Institutes of Health Divider Arrow NCATS

Details

Stereochemistry ACHIRAL
Molecular Formula C16H15N2O6P
Molecular Weight 362.2739
Optical Activity NONE
Defined Stereocenters 0 / 0
E/Z Centers 0
Charge 0

SHOW SMILES / InChI
Structure of FOSPHENYTOIN

SMILES

OP(O)(=O)OCN1C(=O)NC(C1=O)(C2=CC=CC=C2)C3=CC=CC=C3

InChI

InChIKey=XWLUWCNOOVRFPX-UHFFFAOYSA-N
InChI=1S/C16H15N2O6P/c19-14-16(12-7-3-1-4-8-12,13-9-5-2-6-10-13)17-15(20)18(14)11-24-25(21,22)23/h1-10H,11H2,(H,17,20)(H2,21,22,23)

HIDE SMILES / InChI

Molecular Formula C16H15N2O6P
Molecular Weight 362.2739
Charge 0
Count
Stereochemistry ACHIRAL
Additional Stereochemistry No
Defined Stereocenters 0 / 0
E/Z Centers 0
Optical Activity NONE

Description
Curator's Comment: Description was created based on several sources, including http://www.accessdata.fda.gov/drugsatfda_docs/label/2013/020450s020lbl.pdf

Phenytoin is an anti-epileptic drug. Phenytoin has been used with much clinical success against all types of epileptiform seizures, except petit mal epilepsy. Phenytoin is a available for oral administration (tablets, capsules, suspension). CEREBYX® (fosphenytoin sodium injection) is a prodrug intended for parenteral administration; its active metabolite is phenytoin. CEREBYX should be used only when oral phenytoin administration is not possible. Although several potential targets for phenytoin action have been identified within the CNS (Na-K-ATPase, the GABAA receptor complex, ionotropic glutamate receptors, calcium channels and sigma binding sites) to date, though, the best evidence hinges on the inhibition of voltage-sensitive Na channels in the plasma membrane of neurons undergoing seizure activity.

Approval Year

TargetsConditions

Conditions

ConditionModalityTargetsHighest PhaseProduct
Primary
DILANTIN-125

Approved Use

Dilantin (phenytoin) is indicated for the control of tonic-clonic (grand mal) and psychomotor (temporal lobe) seizures

Launch Date

1953
Primary
CEREBYX

Approved Use

CEREBYX is indicated for the control of generalized tonic-clonic status epilepticus and prevention and treatment of seizures occurring during neurosurgery. CEREBYX can also be substituted, short-term, for oral phenytoin. CEREBYX should be used only when oral phenytoin administration is not possible. CEREBYX must not be given orally.

Launch Date

1996
Cmax

Cmax

ValueDoseCo-administeredAnalytePopulation
1.176 μg/mL
100 mg single, oral
dose: 100 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
PHENYTOIN plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: MALE
food status: FASTED
AUC

AUC

ValueDoseCo-administeredAnalytePopulation
32.172 μg × h/mL
100 mg single, oral
dose: 100 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
PHENYTOIN plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: MALE
food status: FASTED
T1/2

T1/2

ValueDoseCo-administeredAnalytePopulation
15.49 h
100 mg single, oral
dose: 100 mg
route of administration: Oral
experiment type: SINGLE
co-administered:
PHENYTOIN plasma
Homo sapiens
population: HEALTHY
age: ADULT
sex: MALE
food status: FASTED
Doses

Doses

DosePopulationAdverse events​
600 mg single, oral
Highest studied dose
unhealthy, 31 years
20 g single, oral
Overdose
Dose: 20 g
Route: oral
Route: single
Dose: 20 g
Sources:
unhealthy, 41 years
Health Status: unhealthy
Age Group: 41 years
Sex: F
Sources:
Other AEs: Sinus bradycardia, Hypotension...
Other AEs:
Sinus bradycardia (1 patient)
Hypotension (severe, 1 patient)
Sources:
5 g single, oral
Overdose
Dose: 5 g
Route: oral
Route: single
Dose: 5 g
Sources:
unhealthy, 49 years
Health Status: unhealthy
Age Group: 49 years
Sex: M
Sources:
Other AEs: Acute respiratory failure...
Other AEs:
Acute respiratory failure (1 patient)
Sources:
60 mg/kg multiple, intravenous
Overdose
Dose: 60 mg/kg
Route: intravenous
Route: multiple
Dose: 60 mg/kg
Sources:
unhealthy, 7 years
Health Status: unhealthy
Age Group: 7 years
Sex: M
Sources:
Other AEs: Encephalopathy...
Other AEs:
Encephalopathy (1 patient)
Sources:
2 g single, oral
Overdose
Dose: 2 g
Route: oral
Route: single
Dose: 2 g
Sources:
unhealthy, adult
Other AEs: Nystagmus, Ataxia...
Other AEs:
Nystagmus (grade 5)
Ataxia (grade 5)
Dysarthria (grade 5)
Tremor (grade 5)
Hyperreflexia (grade 5)
Lethargy (grade 5)
Slurred speech (grade 5)
Blurred vision (grade 5)
Nausea (grade 5)
Vomiting (grade 5)
Sources:
10 mg/kg single, intramuscular
Dose: 10 mg/kg
Route: intramuscular
Route: single
Dose: 10 mg/kg
Sources:
unhealthy, adult
Other AEs: Hypotension, Cardiac arrhythmias...
Other AEs:
Hypotension (severe)
Cardiac arrhythmias
Sources:
10 mg/kg single, intravenous
Dose: 10 mg/kg
Route: intravenous
Route: single
Dose: 10 mg/kg
Sources:
unhealthy, adult
Other AEs: Hypotension, Cardiac arrhythmias...
Other AEs:
Hypotension (severe)
Cardiac arrhythmias
Sources:
AEs

AEs

AESignificanceDosePopulation
Sinus bradycardia 1 patient
20 g single, oral
Overdose
Dose: 20 g
Route: oral
Route: single
Dose: 20 g
Sources:
unhealthy, 41 years
Health Status: unhealthy
Age Group: 41 years
Sex: F
Sources:
Hypotension severe, 1 patient
20 g single, oral
Overdose
Dose: 20 g
Route: oral
Route: single
Dose: 20 g
Sources:
unhealthy, 41 years
Health Status: unhealthy
Age Group: 41 years
Sex: F
Sources:
Acute respiratory failure 1 patient
5 g single, oral
Overdose
Dose: 5 g
Route: oral
Route: single
Dose: 5 g
Sources:
unhealthy, 49 years
Health Status: unhealthy
Age Group: 49 years
Sex: M
Sources:
Encephalopathy 1 patient
60 mg/kg multiple, intravenous
Overdose
Dose: 60 mg/kg
Route: intravenous
Route: multiple
Dose: 60 mg/kg
Sources:
unhealthy, 7 years
Health Status: unhealthy
Age Group: 7 years
Sex: M
Sources:
Ataxia grade 5
2 g single, oral
Overdose
Dose: 2 g
Route: oral
Route: single
Dose: 2 g
Sources:
unhealthy, adult
Blurred vision grade 5
2 g single, oral
Overdose
Dose: 2 g
Route: oral
Route: single
Dose: 2 g
Sources:
unhealthy, adult
Dysarthria grade 5
2 g single, oral
Overdose
Dose: 2 g
Route: oral
Route: single
Dose: 2 g
Sources:
unhealthy, adult
Hyperreflexia grade 5
2 g single, oral
Overdose
Dose: 2 g
Route: oral
Route: single
Dose: 2 g
Sources:
unhealthy, adult
Lethargy grade 5
2 g single, oral
Overdose
Dose: 2 g
Route: oral
Route: single
Dose: 2 g
Sources:
unhealthy, adult
Nausea grade 5
2 g single, oral
Overdose
Dose: 2 g
Route: oral
Route: single
Dose: 2 g
Sources:
unhealthy, adult
Nystagmus grade 5
2 g single, oral
Overdose
Dose: 2 g
Route: oral
Route: single
Dose: 2 g
Sources:
unhealthy, adult
Slurred speech grade 5
2 g single, oral
Overdose
Dose: 2 g
Route: oral
Route: single
Dose: 2 g
Sources:
unhealthy, adult
Tremor grade 5
2 g single, oral
Overdose
Dose: 2 g
Route: oral
Route: single
Dose: 2 g
Sources:
unhealthy, adult
Vomiting grade 5
2 g single, oral
Overdose
Dose: 2 g
Route: oral
Route: single
Dose: 2 g
Sources:
unhealthy, adult
Cardiac arrhythmias
10 mg/kg single, intramuscular
Dose: 10 mg/kg
Route: intramuscular
Route: single
Dose: 10 mg/kg
Sources:
unhealthy, adult
Hypotension severe
10 mg/kg single, intramuscular
Dose: 10 mg/kg
Route: intramuscular
Route: single
Dose: 10 mg/kg
Sources:
unhealthy, adult
Cardiac arrhythmias
10 mg/kg single, intravenous
Dose: 10 mg/kg
Route: intravenous
Route: single
Dose: 10 mg/kg
Sources:
unhealthy, adult
Hypotension severe
10 mg/kg single, intravenous
Dose: 10 mg/kg
Route: intravenous
Route: single
Dose: 10 mg/kg
Sources:
unhealthy, adult
OverviewDrug as perpetrator​

Drug as perpetrator​

TargetModalityActivityMetaboliteClinical evidence
no
no
weak
yes [IC50 145 uM]
yes [IC50 280 uM]
yes [IC50 607 uM]
yes
yes
likely (co-administration study)
Comment: See https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/084427s042lbl.pdf#page=10
yes
likely (co-administration study)
Comment: See https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/084427s042lbl.pdf#page=10
yes
likely (co-administration study)
Comment: See https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/084427s042lbl.pdf#page=11
Page: 46.0
yes
likely (co-administration study)
Comment: See https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/084427s042lbl.pdf#page=9
yes
likely (co-administration study)
Comment: See https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/084427s042lbl.pdf#page=11
yes
yes (co-administration study)
Comment: mean AUC(0-24) of losartan was insignificantly increased by 17% when losartan was coadministered with phenytoin. See more on https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/084427s042lbl.pdf#page=9
Drug as victim

Drug as victim

TargetModalityActivityMetaboliteClinical evidence
no
yes
yes
yes
likely (co-administration study)
Comment: See https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/084427s042lbl.pdf#page=9
yes
yes (co-administration study)
Comment: Coadministration of losartan had no effect on the pharmacokinetics of phenytoin. See more on https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/084427s042lbl.pdf#page8
Page: 8.0
Tox targets

Tox targets

TargetModalityActivityMetaboliteClinical evidence
PubMed

PubMed

TitleDatePubMed
Efficacy of levetiracetam versus fosphenytoin for the recurrence of seizures after status epilepticus.
2017-06
N6-cyclohexyladenosine and 3-(2-carboxypiperazine-4-yl)-1-propenyl-1-phosphonic acid enhance the effect of antiepileptic drugs against induced seizures in mice.
2001-04-17
The teratogenicity of anticonvulsant drugs.
2001-04-12
[Lamotrigine in refractory partial and general epilepsies].
2001-04-11
Evaluation of the neuroprotective effects of sodium channel blockers after spinal cord injury: improved behavioral and neuroanatomical recovery with riluzole.
2001-04
Performance characteristics of four free phenytoin immunoassays.
2001-04
Rocuronium-induced neuromuscular blockade is affected by chronic phenytoin therapy.
2001-04
Stereoselective determination of p-hydroxyphenyl-phenylhydantoin enantiomers in rat liver microsomal incubates by reversed-phase high-performance liquid chromatography using beta-cyclodextrin as chiral mobile phase additives.
2001-04
Decreases in phenytoin hydroxylation activities catalyzed by liver microsomal cytochrome P450 enzymes in phenytoin-treated rats.
2001-04
Inhibition of phenytoin hydroxylation in human liver microsomes by several selective serotonin re-uptake inhibitors.
2001-04
Interaction of plasma proteins with cytochromes P450 mediated metabolic reactions: inhibition by human serum albumin and alpha-globulins of the debrisoquine 4-hydroxylation (CYP2D) in liver microsomes of human, hamster and rat.
2001-03-08
Volume-selective proton MR spectroscopy for in-vitro quantification of anticonvulsants.
2001-03
Fosphenytoin in infants of extremely low birth weight.
2001-03
Influence of retigabine on the anticonvulsant activity of some antiepileptic drugs against audiogenic seizures in DBA/2 mice.
2001-03
Phenytoin-induced cleft palate: evidence for embryonic cardiac bradyarrhythmia due to inhibition of delayed rectifier K+ channels resulting in hypoxia-reoxygenation damage.
2001-03
[Febrile convulsions, Treatment and prognosis].
2001-02-19
[Maintenance dose requirement for phenytoin is lowered in genetically impaired drug metabolism independent of concommitant use of other antiepileptics].
2001-02-17
Nitroso-urea-cisplatin-based chemotherapy associated with valproate: increase of haematologic toxicity.
2001-02
Determination of the antiepileptics vigabatrin and gabapentin in dosage forms and biological fluids using Hantzsch reaction.
2001-02
Refractory idiopathic status epilepticus.
2001-02
Cardiac arrest after fast intravenous infusion of phenytoin mistaken for fosphenytoin.
2001-02
Antiepileptic drug withdrawal in patients with temporal lobe epilepsy undergoing presurgical video-EEG monitoring.
2001-02
Fosphenytoin: pharmacokinetics and tolerance of intramuscular loading doses.
2001-02
Glutamate receptor antagonists differentially affect the protective activity of conventional antiepileptics against amygdala-kindled seizures in rats.
2001-02
Phenytoin intoxication induced by fluvoxamine.
2001-02
The effects of concomitant phenytoin administration on the steady-state pharmacokinetics of quetiapine.
2001-02
Rufinamide: a double-blind, placebo-controlled proof of principle trial in patients with epilepsy.
2001-02
Possible function of astrocyte cytochrome P450 in control of xenobiotic phenytoin in the brain: in vitro studies on murine astrocyte primary cultures.
2001-02
Myotoxicity studies of injectable biodegradable in-situ forming drug delivery systems.
2001-01-05
Interferon-alpha2a and 13-cis-retinoic acid with radiation treatment for high-grade glioma.
2001-01
Inhibition of human cytochrome P450 isoforms by nonnucleoside reverse transcriptase inhibitors.
2001-01
Electrophysiological and pharmacological properties of the human brain type IIA Na+ channel expressed in a stable mammalian cell line.
2001-01
Hair analysis for pharmaceutical drugs. I. Effective extraction and determination of phenobarbital, phenytoin and their major metabolites in rat and human hair.
2001-01
Ritonavir-induced carbamazepine toxicity.
2001-01
Treatment of nonfebrile status epilepticus in Rochester, Minn, from 1965 through 1984.
2001-01
Effects of antiepileptic drugs on rat platelet aggregation: ex vivo and in vitro study.
2001-01
Effects of phenytoin on glutathione status and oxidative stress biomarker gene mRNA levels in cultured precision human liver slices.
2001-01
Successful treatment of antiepileptic drug hypersensitivity syndrome with intravenous immune globulin.
2001-01
Drugs for discoid lupus erythematosus.
2001
II. An altered proliferation response due to the anticonvulsant phenytoin (PHT) in epileptic patients.
2001
I. The modulatory effect in genotoxic responses due to age and duration of PHT-therapy in epileptic patients.
2001
Acute fulminant hepatic failure in a woman treated with phenytoin and trimethoprim-sulfamethoxazole.
2000-12
Phenytoin, midazolam, and naloxone protect against fentanyl-induced brain damage in rats.
2000-12
Purple glove syndrome caused by oral administration of phenytoin.
2000-11
Effects of combined administration of zonisamide and valproic acid or phenytoin to nitric oxide production, monoamines and zonisamide concentrations in the brain of seizure-susceptible EL mice.
2000-09-15
Phenytoin poisoning after using Chinese proprietary medicines.
2000-07
Anticonvulsant-induced suppression of IFN-gamma production by lymphocytes obtained from cervical lymph nodes in glioma-bearing mice.
2000-04
Procainamide and phenytoin. Comparative study of their antiarrhythmic effects at apparent therapeutic plasma levels.
1975-07
Harmful effect of megadoses of vitamins: electroencephalogram abnormalities and seizures induced by intravenous folate in drug-treated epileptics.
1975-01
The influence of aldosterone and anticonvulsant drugs on electroencephalographic and clinical disturbances induced by the spirolactone derivative, potassium canrenoate.
1975-01
Patents

Sample Use Guides

Dilantin-125® (Phenytoin Oral Suspension, USP), each 5 ml of suspension contains 125 mg of phenytoin: Patients who have received no previous treatment may be started on one teaspoonful (5 mL) of Dilantin-125 Suspension three times daily, and the dose is then adjusted to suit individual requirements. An increase to five teaspoonfuls daily may be made, if necessary. CEREBYX® (fosphenytoin sodium injection) is a prodrug intended for parenteral administration; its active metabolite is phenytoin. 1.5 mg of fosphenytoin sodium is equivalent to 1 mg phenytoin sodium, and is referred to as 1 mg phenytoin sodium equivalents (PE). CEREBYX should be used only when oral phenytoin administration is not possible. Dosage (Status Epilepticus): The loading dose of CEREBYX is 15 to 20 mg PE/kg administered at 100 to 150 mg PE/min.
Route of Administration: Other
Exposure of human adult keratinocytes (HaCaT cells) for 48 h to alkyd nanoemulsions producing phenytoin concentrations of 3.125-200 μg/mL resulted in relative cell viability readings using tetrazolium dye 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide of 100% confirming nontoxicity and suggesting cell proliferation activity.
Substance Class Chemical
Created
by admin
on Mon Mar 31 18:08:09 GMT 2025
Edited
by admin
on Mon Mar 31 18:08:09 GMT 2025
Record UNII
B4SF212641
Record Status Validated (UNII)
Record Version
  • Download
Name Type Language
FOSPHENYTOIN
HSDB   INN   MI   VANDF   WHO-DD  
INN  
Official Name English
3-(HYDROXYMETHYL)-5,5-DIPHENYLHYDANTOIN, PHOSPHATE (ESTER)
Preferred Name English
FOSPHENYTOIN [HSDB]
Common Name English
FOSPHENYTOIN [VANDF]
Common Name English
Fosphenytoin [WHO-DD]
Common Name English
FOSPHENYTOIN [MI]
Common Name English
fosphenytoin [INN]
Common Name English
NP-06
Common Name English
2,4-IMIDAZOLIDINEDIONE, 5,5-DIPHENYL-3-((PHOSPHONOOXY)METHYL)-
Systematic Name English
Classification Tree Code System Code
NDF-RT N0000008486
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
WHO-ATC N03AB05
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
WHO-VATC QN03AB05
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
NCI_THESAURUS C264
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
LIVERTOX NBK547879
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
NDF-RT N0000175753
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
FDA ORPHAN DRUG 55790
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
Code System Code Type Description
EPA CompTox
DTXSID9044299
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY
NCI_THESAURUS
C65766
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY
WIKIPEDIA
FOSPHENYTOIN
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY
EVMPD
SUB07804MIG
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY
HSDB
7523
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY
FDA UNII
B4SF212641
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY
SMS_ID
100000080442
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY
LACTMED
Fosphenytoin
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY
IUPHAR
7190
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY
PUBCHEM
56339
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY
ChEMBL
CHEMBL1201336
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY
DRUG BANK
DB01320
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY
MESH
C043114
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY
RXCUI
72236
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY RxNorm
INN
6484
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY
DRUG CENTRAL
1247
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY
CAS
93390-81-9
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY
MERCK INDEX
m5555
Created by admin on Mon Mar 31 18:08:09 GMT 2025 , Edited by admin on Mon Mar 31 18:08:09 GMT 2025
PRIMARY Merck Index
Related Record Type Details
SALT/SOLVATE -> PARENT
METABOLIC ENZYME -> INDUCER
SALT/SOLVATE -> PARENT
BINDER->LIGAND
BINDING
Related Record Type Details
ACTIVE MOIETY
Name Property Type Amount Referenced Substance Defining Parameters References
Volume of Distribution PHARMACOKINETIC