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Phenytoin
Aka: Phenytoin, Dilantin, Diphenylhydantoin, DPH, Hydantoin, Mephenytoin, Ethotoin, Phenacemide- Classification: Hydantoin
- Phenytoin (Dilantin)
- Phenytoin congeners (limited use)
- Mephenytoin
- Ethotoin
- Phenacemide
- History
- Oldest non-sedative antiepileptic drug (1938)
- Based on research into phenobarbital antiseizure effect
- Indications
- Contraindications
- Pregnancy (See Fetal Hydantoin Syndrome)
- Pharmacokinetics
- Hepatic metabolism
- Highly protein bound
- Half-life: 12 to 36 hours
- Average half life for moderate dosages: 24 hours
- Very long half-life at toxic concentrations
- Therapeutic level: 10-20 ug/ml
- Dosing: Adults
- Loading dose
- Oral loading regimen
- Dose 1: 400 mg PO
- Dose 2: 300 mg PO at 2 hours after dose 1
- Dose 3: 300 mg PO at 4 hours after dose 1
- Parenteral loading regimen
- Dose: 10-20 mg/kg (average 1 gram) IV
- Do not administer faster than 50 mg/min
- Oral loading regimen
- Maintenance dose
- Initial: 5 mg/kg to 300 mg/day divided qd to tid
- Titrating dose
- Avoid increasing dose by >25-30 mg per trial
- Wait for steady state (7 days) before level recheck
- Loading dose
- Drug Interactions
- Drugs that increase plasma Phenytoin levels
- Amiodarone
- Clobazam
- Fluconazole
- Ranitidine
- Phenylbutazone
- Sulfonamides
- Benzodiazepines
- Anticoagulants
- Isoniazid
- Drugs that decrease Phenytoin level or free fraction
- Influenza Vaccine
- Tolbutamide
- Carboplatin
- Rifampicin
- Theophylline
- Phenobarbital
- Carbamazepine
- Phenytoin decreases plasma level of other drug
- Doxorubicin
- Drugs that increase plasma Phenytoin levels
- Adverse Effects
- See Dilantin Toxicity
- Fetal Hydantoin Syndrome
- Drug hypersensitivity
- Common chronic changes associated with Phenytoin
- Gingival Hyperplasia
- Hirsutism
- Coarse facial features
- Peripheral Neuropathy (decreased Deep Tendon Reflex)
- Other effects
- Hepatotoxicity
- Stevens-Johnson Syndrome
- Pancreatitis
- Osteoporosis
- Folic Acid deficiency
| Medication Costs | ||
|---|---|---|
| Phenytoin (on 2/9/2012 at DrugStore.com) | ||
| Phenytoin 125mg/5ml Suspension | #237 for $28.98 | ($0.12/unit) |
| Phenytoin Sodium Extended (on 2/9/2012 at DrugStore.com) | ||
| Phenytoin Sodium Extended 100mg Capsules | #90 for $31.99 | ($0.36/unit) |
| Dilantin Infatabs (on 2/9/2012 at DrugStore.com) | ||
| Dilantin Infatabs 50mg Chew Tabs | #90 for $53.99 | ($0.60/unit) |
| Dilantin (on 2/9/2012 at DrugStore.com) | ||
| Dilantin 100mg Capsules | #90 for $58.99 | ($0.66/unit) |
| Dilantin 125mg/5ml Suspension 237ml Bottle | #1 for $82.99 | ($82.99/unit) |
| Dilantin 30mg Capsules | #90 for $54.99 | ($0.61/unit) |
| FPNotebook does not benefit financially from showing this medication data or their pharmacy links. This information is provided only to help medical providers and their patients see relative costs. Insurance plans negotiate lower medication prices with suppliers. Prices shown here are out of pocket, non-negotiated rates. See Needy Meds for financial assistance information. | ||
Ethotoin (C0015046) |
|
|---|---|
| Definition (NCI) | A hydantoin anticonvulsant with anti-epileptic activity. The mechanism of action is not completely known, but is thought to be fairly similar to phenytoin. Ethotoin influences synaptic transmission by altering sodium and calcium ion influx across neuronal membranes in the repolarization, depolarization, and membrane stability phase and interferes with the calcium uptake in presynaptic terminals. This inhibits neuronal firing and results in the stabilization of neuronal membranes, thereby preventing the spread of seizure activity at the motor cortex. |
| Concepts | Organic Chemical (T109) , Pharmacologic Substance (T121) |
| MSH | C084606 |
| SnomedCT | 64463006, 371384002 |
| English | ethotoin, 2,4-Imidazolidinedione, 3-ethyl-5-phenyl-, 3-ethyl-5-phenyl-2,4-imidazolidinedione, Hydantoin, 3-ethyl-5-phenyl-, ethotoin (medication), ETHOTOIN, ethotoin [Chemical/Ingredient], Ethylphenylhydantoin, Ethotoin (substance), Ethotoin product (product), Ethotoin product, Ethotoin |
| Spanish | etotoína (producto), etotoína, producto (producto), etotoína, producto, etilfenilhidantoína, etotoína (sustancia), etotoína |
| Sources |
Derived from the NIH UMLS (Unified Medical Language System) |
Hydantoins (C0020209) |
|
|---|---|
| Definition (MSH) | Compounds based on imidazolidine dione. Some derivatives are ANTICONVULSANTS. |
| Concepts | Organic Chemical (T109) , Pharmacologic Substance (T121) |
| MSH | D006827 |
| English | Hydantoins, HYDANTOINS, Imidazolidine 2,4 Diones, Imidazolidine-2,4-Diones, 616 HYDANTOINS, Hydantoins [Chemical/Ingredient], hydantoin, hydantoins |
| Swedish | Hydantoiner |
| Czech | hydantoiny |
| Finnish | Hydantoiinit |
| Russian | GIDANTOINY, ETOTOIN, ГИДАНТОИНЫ, ЭТОТОИН |
| Croatian | Not Translated[Hydantoins] |
| Spanish | Hidantoínas, Hidantoinas |
| Polish | Hydantoiny pochodne |
| Japanese | グリコリル尿素, ヒダントイン |
| French | Hydantoïnes |
| German | Hydantoine |
| Italian | Idantoine |
| Portuguese | Hidantoínas |
| Sources |
Derived from the NIH UMLS (Unified Medical Language System) |
Mephenytoin (C0025381) |
|
|---|---|
| Definition (NCI) | A heterocyclic organic compound with anticonvulsant property. Although the mechanism of action is not well established, mephenytoin potentially promotes sodium efflux from neurons in motor cortex, and stabilizes the threshold against hyperexcitability caused by excessive stimulation. Thus this agent reduces the membrane sodium gradient and prevents cortical seizure signal spreading. It may cause blood dyscrasias, therefore, this agent was only used after other less toxic anticonvulsants had failed. |
| Definition (MSH) | An anticonvulsant effective in tonic-clonic epilepsy (EPILEPSY, TONIC-CLONIC). It may cause blood dyscrasias. |
| Concepts | Organic Chemical (T109) , Pharmacologic Substance (T121) |
| MSH | D008617 |
| SnomedCT | 28344001, 417526007 |
| English | Mefenetoin, Mephenytoin, Methoin, Methyl Phenetoin, Phenetoin, Methyl, 2,4-Imidazolidinedione, 5-ethyl-3-methyl-5-phenyl-, 5 Ethyl 3 Methyl 5 Phenylhydantoin, 5-Ethyl-3-Methyl-5-Phenylhydantoin, mephenytoin, mephenytoin (discontinued) (medication), mephenytoin (discontinued), Mephenytoin [Chemical/Ingredient], 3-Methyl-5,5-phenylethylhydantoin, 3-Ethylnirvanol, Methylphenylethylhydantoin, Mephenytoin (substance), Mephenytoin (product), MEPHENYTOIN |
| Czech | mefenytoin |
| Finnish | Mefenytoiini |
| Russian | METILFENETOIN, MEFENITOIN, METOIN, МЕТИЛФЕНЕТОИН, МЕТОИН, МЕФЕНИТОИН |
| Japanese | メチルフェネトイン, メトイン, フェナントイン, メフェニトイン |
| Swedish | Mefenytoin |
| Spanish | Mefenitoína, Metil Fenetoina, Metoina, Metoína, Metil Fenetoína, Mefenitoina, mefenitoína (sustancia), mefenitoína, metilfeniletilhidantoína, metoína, mefenitoína (producto) |
| Polish | Mefenytoina, Mezantoina |
| French | Méphénytoïne |
| German | Mephenytoin, Methoin, Methylphenetoin |
| Italian | Mefenitoina |
| Portuguese | Mefenitoína, Metilfenetoína, Metoína |
| Sources |
Derived from the NIH UMLS (Unified Medical Language System) |
Phenytoin (C0031507) |
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|---|---|
| Definition (MSH) | 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. |
| Definition (CSP) | anticonvulsant used in a wide variety of seizures; also an anti-arrhythmic and a muscle relaxant. |
| Definition (NCI) | A hydantoin derivative and a non-sedative antiepileptic agent with anticonvulsant activity. Phenytoin potentially acts by promoting sodium efflux from neurons located in the motor cortex reducing post-tetanic potentiation at synapses. The reduction of potentiation prevents cortical seizure foci spreading to adjacent areas, stabilizing the threshold against hyperexcitability. In addition, this agent appears to reduce sensitivity of muscle spindles to stretch causing muscle relaxation. |
| Concepts | Organic Chemical (T109) , Pharmacologic Substance (T121) |
| MSH | D010672 |
| SnomedCT | 387220006, 40556005, 255672002 |
| English | Phenytoin, 5,5-Diphenylhydantoin, Diphenylhydantoin, Fenitoin, 2,4-Imidazolidinedione, 5,5-diphenyl-, 5,5-Diphenyl-2,4-imidazolidinedione, diphenylhydantoin, Phenytoin - chemical, Phenytoin [Chemical/Ingredient], dph, diphenylhydantoins, fenitoin, phenytoin, PHENYTOIN, DPH, Phenylhydantoin, Phenytoin product, Phenytoin (product), Phenytoin (substance), Phenytoin - chemical (substance) |
| Swedish | Fenytoin |
| Czech | fenytoin, difenylthiohydantoin, difenylhydantoin |
| Finnish | Fenytoiini |
| Russian | DIFENIN, FENITOIN, FENANTOIN, DIFENILTIOGIDANTOIN, DIFENILGIDANTOIN, ДИФЕНИЛГИДАНТОИН, ДИФЕНИЛТИОГИДАНТОИН, ДИФЕНИН, ФЕНАНТОИН, ФЕНИТОИН |
| Japanese | ヒダントール, ジランチン, フェニトイン, アレビアチン, ジフェニルヒダントイン, ジフェニルヒダントインナトリウム, フェニトインナトリウム |
| Italian | Difenilidantoina, 5,5-Difenilidantoina, Fenitoina |
| Croatian | FENITOIN |
| Spanish | Fenitoína, Fenitoina, Difenilhidantoína, Difenilhidantoina, difenilhidantoína, fenitoína (producto), fenitoína (sustancia), fenitoína - químico (sustancia), fenitoína - químico, fenitoína |
| Polish | Fenytoina, Dilantin, Epanutin |
| French | Phénytoïne |
| German | Diphenylhydantoin, Fenitoin, Phenytoin |
| Portuguese | Difenilidantoína, Fenitoína |
| Sources |
Derived from the NIH UMLS (Unified Medical Language System) |
phenacemide (C0070525) |
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|---|---|
| Concepts | Organic Chemical (T109) , Pharmacologic Substance (T121) |
| MSH | C005396 |
| SnomedCT | 18712002, 400358006 |
| English | (phenylacetyl)urea, benzeneacetamide, N-(aminocarbonyl)-, phenacemide, phenuron, phenacemide [Chemical/Ingredient], phenylacetylurea, Phenacemide, Phenylacetylcarbamide, Phenylacetylurea, Phenacemide (product), Phenacemide (substance), PHENACEMIDE |
| Spanish | fenacemida (producto), fenacemida (sustancia), fenacemida, fenilacetilcarbamida, fenilacetilurea |
| Sources |
Derived from the NIH UMLS (Unified Medical Language System) |
Dilantin (C0699512) |
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|---|---|
| Definition (CHV) | a kind of epilepsy treatment drug |
| Concepts | Organic Chemical (T109) , Pharmacologic Substance (T121) |
| MSH | D010672 |
| English | dilantin, Dilantin |
| Sources |
Derived from the NIH UMLS (Unified Medical Language System) |