Toxno Substance Profile
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Substance Name

Phenytoin
Identification Number: CASRN | 57-41-0

  Substance Attributes


  • Known Human Carcinogen

    This is a serious nasty substance. Exposure to this substance leads to cancer in Humans. Exercise extreme caution with this substance, explore your exposure routes and very seriously consider complete avoidance. See further details under Toxins.

  • Birth/Developmental

    Known to effect development of fetus.

  • Metabolic Interference or Disruption

    Interferes with human metabolism. This can be a very serious thing. Some of these interference mechanics are well established. However, often long term effects and health consequences remain largely unknown. Additionally an emerging area of concern and one that is not currently studied, is the combined synergistic effects these metabolically disrupting chemicals have on human health.


    Metabolic interference happens when the substance produces highly reactive and often damaging intermediates during detoxification or when the substance binds to specific enzymes, important structural groups on molecules, receptors and membranes or targets DNA or mimics key nutrients.

  • Exposure Produces Health Symptoms

    Symptoms maybe short term or long term depending on the exposure duration and intensity and effects areas like Cardiovascular, Gastrointestinal, Cognition, Fatigue. A substance with this attribute may cause an allergic skin reaction, serious eye irritation, allergy or asthma symptoms or breathing difficulties if inhaled.

  • Has known Side Effects

    This is often the result of long or short term medication use. The same medication can have a range of side effects ranging from none at all to totally debilitating symptoms within different individuals. Reasons for this include individual genetics, individual detoxification capacity, nutrition status, duration of use and total number of medications being taken.


    It becomes very difficult to establish clear causes of symptoms when multiple medications are being taken at once.


    See SIDE EFFECTS LINKOUT at end of this profile.

These attributes are ONLY based on peer-reviewed evidence. See link to Data Sources below. Everyone benefits from knowing this stuff. Please Share.



  • CATEGORIES: Medication or Drug | Synthetic Toxin | PESTICIDE active ingredient | Pesticide or Plant Growth Regulator Approved in Australia | Medication Approved in Australian (on the PBS) | Medication Approved in USA
  • SUBSTANCE LINEAGE: Organic Compounds | Benzenoids | Benzene and Substituted Derivatives | Diphenylmethanes | Phenylhydantoins
  • SYNONYMS: 5,5-Diphenyl-imidazolidine-2,4-dione | 5,5-Diphenylhydantoin | 5,5-diphenylimidazolidine-2,4-dione | 5,5-diphenyltetrahydro-1H-2,4-imidazoledione | 5,5-Diphenyltetrahydro-1H-2,4-imidazoledione | 5,5-Dwufenylohydantoina | Dihydantoin | DILANTIN | Dilantin-125 | Diphenylan Sodium | Diphenylhydantoin | Diphenylhydatanoin | Epanutin | Eptoin | Fenitoina | PHENTYTOIN | Phenytek | Phenytoin Sodium | Phenytoine | Phenytoinum
  • DESCRIPTION: An anticonvulsant that is used in a wide variety of seizures. It is also an anti-arrhythmic and a muscle relaxant. The mechanism of therapeutic action is not clear, although several cellular actions have been described including effects on ion channels, active transport, and general membrane stabilization. The mechanism of its muscle relaxant effect appears to involve a reduction in the sensitivity of muscle spindles to stretch. Phenytoin has been proposed for several other therapeutic uses, but its use has been limited by its many adverse effects and interactions with other drugs.
  • COMMENTS: Residues of this pesticide are NOT tested for on Australian Foods even though the Pesticide is approved in Australia. This is partly so because this pesticide is not usually used around food agriculture. | Pesticide approved in Australia
  • toxin chemical structure pubchem
  • FORMULA: C15H12N2O2
  • DATA SOURCES: DATA SOURCES: T3DB | PubChem | IARC | NTP | OEHHA | APVMA | Drugbank | Australian Approved Medications PBS | USA FDA APPROVED DRUG PRODUCTS
  • LAST UPDATE: 28/04/2018

  Health Associations

Mostly focused on Health Implications of Long Term Exposure to this substance

  • SYMPTOMS: Symptoms of overdose include coma, difficulty in pronouncing words correctly, involuntary eye movement, lack of muscle coordination, low blood pressure, nausea, sluggishness, slurred speech, tremors, and vomiting.
  • POSSIBLE HEALTH CONSEQUENCES: May cause a potentially dangerous rash that may develop into Stevens Johnson syndrome, an extremely rare but potentially fatal skin disease. | Primarily hepatic. The majority of the dose (up to 90%) is metabolized to 5-(4'-hydroxyphenyl)-5-phenylhydantoin (p-HPPH). This metabolite undergoes further glucuronidation and is excreted into the urine. CYP2C19 and CYP2C9 catalyze the aforementioned reaction. Route of Elimination: Most of the drug is excreted in the bile as inactive metabolites which are then reabsorbed from the intestinal tract and excreted in the urine. Urinary excretion of phenytoin and its metabolites occurs partly with glomerular filtration but, more importantly, by tubular secretion. Half Life: 22 hours (range of 7 to 42 hours)
  • ACTION OF TOXIN: Phenytoin acts on sodium channels on the neuronal cell membrane, limiting the spread of seizure activity and reducing seizure propagation. By promoting sodium efflux from neurons, phenytoin tends to stabilize the threshold against hyperexcitability caused by excessive stimulation or environmental changes capable of reducing membrane sodium gradient. This includes the reduction of post-tetanic potentiation at synapses. Loss of post-tetanic potentiation prevents cortical seizure foci from detonating adjacent cortical areas. | Phenytoin acts on sodium channels on the neuronal cell membrane, limiting the spread of seizure activity and reducing seizure propagation. By promoting sodium efflux from neurons, phenytoin tends to stabilize the threshold against hyperexcitability caused by excessive stimulation or environmental changes capable of reducing membrane sodium gradient. This includes the reduction of post-tetanic potentiation at synapses. Loss of post-tetanic potentiation prevents cortical seizure foci from detonating adjacent cortical areas.
  • TOXIN SITES OF ACTION IN CELL: "Cytoplasm", "Extracellular", "Membrane"
  • Additional Exposure Routes: For the control of generalized tonic-clonic (grand mal) and complex partial (psychomotor, temporal lobe) seizures and prevention and treatment of seizures occurring during or following neurosurgery.
  • SEE MEDICATION SIDE EFFECTS

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  Exposure Routes

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