Fosfenitoína (fosphenytoin sodium)

Para qué se usa Fosfenitoína

Cita de la sección «Indications and Usage» (indicaciones y uso) de la etiqueta aprobada por la FDA. Se muestra en inglés, tal como la publica la FDA.

CEREBYX is indicated for the treatment 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 […]. …

— Etiqueta de la FDA: Cerebyx, Pfizer Laboratories Div Pfizer Inc, vigente desde el 18 de mayo de 2025. Leer la etiqueta completa en DailyMed →

Etiqueta citada: la de la presentación más común (injection, solution, intramuscular), Cerebyx, Pfizer Laboratories Div Pfizer Inc; abarca 2 productos del directorio NDC de la FDA. Las citas sobre efectos secundarios, interacciones, dosis y embarazo de abajo vienen de esta misma etiqueta.

La FDA tiene 10 etiquetas para productos de este medicamento (distintos fabricantes y presentaciones); los usos pueden variar. Revise la etiqueta de su propio medicamento.

Esta página no es un consejo médico. Hable con su médico o farmacéutico antes de empezar, dejar o cambiar cualquier medicamento.

Advertencia en recuadro

La advertencia en recuadro («caja negra») es la advertencia más seria de la FDA en la etiqueta de un medicamento, para riesgos graves o mortales.

Esta etiqueta tiene una advertencia en recuadro. Su título: WARNING: CARDIOVASCULAR RISK ASSOCIATED WITH RAPID INFUSION RATES. Leerla en la etiqueta completa →

9 de 10 etiquetas de la FDA de este medicamento tienen advertencia en recuadro.

Fosfenitoína: lo que dice la advertencia en recuadro

Cita de la advertencia en recuadro (Boxed Warning) de la etiqueta aprobada por la FDA. Se muestra en inglés.

WARNING: CARDIOVASCULAR RISK ASSOCIATED WITH RAPID INFUSION RATES The rate of intravenous CEREBYX administration should not exceed 150 mg phenytoin sodium equivalents (PE) per minute in adults and 2 mg PE/kg/min (or 150 mg PE/min, whichever is slower) in pediatric patients because of the risk of severe hypotension and cardiac arrhythmias. Careful cardiac monitoring is needed during and after administering intravenous CEREBYX.

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Although the risk of cardiovascular toxicity increases with infusion rates above the recommended infusion rate, these events have also been reported at or below the recommended infusion rate. Reduction in rate of administration or discontinuation of dosing may be needed [see Dosage and Administration (2.3, 2.4) and Warnings and Precautions (5.2)]. WARNING: CARDIOVASCULAR RISK ASSOCIATED WITH RAPID INFUSION RATES See full prescribing information for complete boxed warning.

• The rate of intravenous CEREBYX administration should not exceed 150 mg phenytoin sodium equivalents (PE) per minute in adults and 2 mg PE/kg/min (or 150 mg PE/min, whichever is slower) in pediatric patients because of the risk of severe hypotension and cardiac arrhythmias.
• Careful cardiac monitoring is needed during and after administering intravenous CEREBYX.
• Reduction in rate of administration or discontinuation of dosing may be needed (2.3, 2.4, 5.2).

— Etiqueta de la FDA: Cerebyx, Pfizer Laboratories Div Pfizer Inc, vigente desde el 18 de mayo de 2025. Leer la etiqueta completa en DailyMed →

Efectos secundarios de Fosfenitoína

Cita de la sección «Adverse Reactions» (reacciones adversas) de la etiqueta aprobada por la FDA. Se muestra en inglés. Avise a su médico de cualquier efecto secundario que le preocupe.

The following serious adverse reactions are described elsewhere in the labeling:

• Cardiovascular Risk Associated with Rapid Infusion [see Warnings and Precautions (5.2)]
• Withdrawal Precipitated Seizure, Status Epilepticus [see Warnings and Precautions (5.3)]
• Serious Dermatologic Reactions [see Warnings and Precautions (5.4)]
• Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)/Multiorgan Hypersensitivity [see Warnings and Precautions (5.5)]
• Hypersensitivity …

— Etiqueta de la FDA: Cerebyx, Pfizer Laboratories Div Pfizer Inc, vigente desde el 18 de mayo de 2025. Esto es solo una parte de la sección. Leer la etiqueta completa en DailyMed →

Interacciones de Fosfenitoína

Cita de la sección «Drug Interactions» (interacciones) de la etiqueta aprobada por la FDA. Se muestra en inglés. Dígale a su farmacéutico todos los medicamentos, vitaminas y productos herbales que toma.

Fosphenytoin is extensively bound to human plasma proteins. Drugs highly bound to albumin could increase the unbound fraction of fosphenytoin. Although, it is unknown whether this could result in clinically significant effects, caution is advised when administering CEREBYX with other drugs that significantly bind to serum albumin. The most significant drug interactions following administration of CEREBYX are expected to occur with drugs that interact with phenytoin.

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Phenytoin is extensively bound to serum plasma proteins and is prone to competitive displacement. Phenytoin is primarily metabolized by the hepatic cytochrome P450 enzyme CYP2C9 and to a lesser extent by CYP2C19 and is particularly susceptible to inhibitory drug interactions because it is subject to saturable metabolism. Inhibition of metabolism may produce significant increases in circulating phenytoin concentrations and enhance the risk of drug toxicity. Monitoring of phenytoin serum levels is recommended when a drug interaction is suspected. Phenytoin or CEREBYX is a potent inducer of hepatic drug-metabolizing enzymes.

• Multiple drug interactions because of extensive plasma protein binding, saturable metabolism, and potent induction of hepatic enzymes (7.1, 7.2) 7.1 Drugs that Affect Phenytoin or CEREBYX Table 6 includes commonly occurring drug interactions that affect phenytoin (the active metabolite of CEREBYX) concentrations. However, this list is not intended to be inclusive or comprehensive. Individual prescribing information from relevant drugs should be consulted. The addition or withdrawal of these agents in patients on phenytoin therapy may require an adjustment of the phenytoin dose to achieve optimal clinical outcome. Table 6. Drugs That Affect Phenytoin Concentrations Interacting Agent Examples Drugs that may increase phenytoin serum levels Antiepileptic drugs Ethosuximide, felbamate, oxcarbazepine, methsuximide, topiramate Azoles Fluconazole, ketoconazole, itraconazole, miconazole, voriconazole Antineoplastic agents Capecitabine, fluorouracil Antidepressants Fluoxetine, fluvoxamine, sertraline Gastric acid reducing agents H 2 antagonists (cimetidine), omeprazole Sulfonamides Sulfamethizole, sulfaphenazole, sulfadiazine, sulfamethoxazole-trimethoprim Other Acute alcohol intake, amiodarone, chloramphenicol, chlordiazepoxide, disulfiram, estrogen, fluvastatin, isoniazid, methylphenidate, phenothiazines, salicylates, ticlopidine, tolbutamide, trazodone, warfarin Drugs that may decrease phenytoin serum levels Antineoplastic agents usually in combination Bleomycin, carboplatin, cisplatin, doxorubicin, methotrexate Antiviral agents Fosamprenavir, nelfinavir, ritonavir Antiepileptic drugs Carbamazepine, vigabatrin Other Chronic alcohol abuse, diazepam, diazoxide, folic acid, reserpine, rifampin, St. John's wort, The induction potency of St. John's wort may vary widely based on preparation. theophylline Drugs that may either increase or decrease phenytoin serum levels Antiepileptic drugs Phenobarbital, valproate sodium, valproic acid 7.2 Drugs Affected by Phenytoin or CEREBYX Table 7 includes commonly occurring drug interactions affected by phenytoin (the active metabolite of CEREBYX).

— Etiqueta de la FDA: Cerebyx, Pfizer Laboratories Div Pfizer Inc, vigente desde el 18 de mayo de 2025. Esto es solo una parte de la sección. Leer la etiqueta completa en DailyMed →

Dosis de Fosfenitoína

Cita de la sección «Dosage and Administration» (dosis y administración) de la etiqueta aprobada por la FDA. Se muestra en inglés. Su dosis es la que le receta su médico: no la cambie por su cuenta.

• The dose, concentration, and infusion rate of CEREBYX should always be expressed as phenytoin sodium equivalents (PE) (2.1)
• For Status Epilepticus: o Adult loading dose is 15 to 20 mg PE/kg at a rate of 100 to 150 mg PE/min (2.3) o Pediatric loading dose is 15 to 20 mg PE/kg at a rate of 2 mg PE/kg/min (or 150 mg PE/min, whichever is slower) (2.3)
• For Non-emergent Loading and Maintenance Dosing: o Adult loading dose is 10 to 20 mg PE/kg given IV or IM; initial …

— Etiqueta de la FDA: Cerebyx, Pfizer Laboratories Div Pfizer Inc, vigente desde el 18 de mayo de 2025. Esto es solo una parte de la sección. Leer la etiqueta completa en DailyMed →

Fosfenitoína en el embarazo

Cita de la parte sobre embarazo (Pregnancy) de la etiqueta aprobada por la FDA. Se muestra en inglés. Pregunte a su médico antes de tomar cualquier medicamento si está embarazada o planea estarlo.

Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to antiepileptic drugs (AEDs), such as CEREBYX, during pregnancy. Physicians are advised to recommend that pregnant patients taking CEREBYX enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry. This can be done by calling the toll-free number 1-888-233-2334, and must be done by patients themselves.

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Information on the registry can also be found at the website http://www.aedpregnancyregistry.org/. Risk Summary In humans, prenatal exposure to phenytoin (the active metabolite of CEREBYX) may increase the risks for congenital malformations and other adverse developmental outcomes. Prenatal phenytoin exposure is associated with an increased incidence of major malformations, including orofacial clefts and cardiac defects. In addition, the fetal hydantoin syndrome, a pattern of abnormalities including dysmorphic skull and facial features, nail and digit hypoplasia, growth abnormalities (including microcephaly), and cognitive deficits has been reported among children born to epileptic women who took phenytoin alone or in combination with other antiepileptic drugs during pregnancy [see Data]. There have been several reported cases of malignancies, including neuroblastoma, in children whose mothers received phenytoin during pregnancy. Administration of phenytoin to pregnant animals resulted in an increased incidence of fetal malformations and other manifestations of developmental toxicity (including embryofetal death, growth impairment, and behavioral abnormalities) in multiple species at clinically relevant doses [see Data]. In the U.S. general population, the estimated background risk of major birth defects and of miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown. Clinical Considerations Disease-associated maternal risk An increase in seizure frequency may occur during pregnancy because of altered phenytoin pharmacokinetics. Periodic measurement of serum phenytoin concentrations may be valuable in the management of pregnant women as a guide to appropriate adjustment of dosage [see Dosage and Administration (2.5, 2.9)]. However, postpartum restoration of the original dosage will probably be indicated. Fetal/Neonatal adverse reactions A potentially life-threatening bleeding disorder related to decreased levels of vitamin K-dependent clotting factors may occur in newborns exposed to phenytoin in utero. This drug-induced condition can be prevented with vitamin K administration to the mother before delivery and to the neonate after birth. Data Human Data Meta-analyses using data from published observational studies and registries have estimated an approximately 2.4-fold increased risk for any major malformation in children with prenatal phenytoin exposure compared to controls. An increased risk of heart defects, facial clefts, and digital hypoplasia has been reported.

— Etiqueta de la FDA: Cerebyx, Pfizer Laboratories Div Pfizer Inc, vigente desde el 18 de mayo de 2025. Esto es solo una parte de la sección. Leer la etiqueta completa en DailyMed →

Cuándo no se debe usar Fosfenitoína

Cita de la sección «Contraindications» (contraindicaciones) de la etiqueta aprobada por la FDA. Se muestra en inglés.

CEREBYX is contraindicated in patients with:

• A history of hypersensitivity to CEREBYX or its inactive ingredients, or to phenytoin or other hydantoins [see Warnings and Precautions (5.6)]. Reactions have included angioedema.
• Sinus bradycardia, sino-atrial block, second and third degree A-V block, or Adams-Stokes syndrome because of the effect of parenteral phenytoin or CEREBYX on ventricular automaticity.

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• A history of prior acute hepatotoxicity attributable to CEREBYX or phenytoin [see Warnings and Precautions (5.8)].
• Coadministration with delavirdine because of the potential for loss of virologic response and possible resistance to delavirdine or to the class of non-nucleoside reverse transcriptase inhibitors.
• Hypersensitivity to CEREBYX, its ingredients, phenytoin, hydantoins (4)
• Sinus bradycardia, sino-atrial block, second and third degree A-V block, and Adams-Stokes syndrome (4)
• A history of prior acute hepatotoxicity attributable to CEREBYX or phenytoin (4, 5.8)
• Coadministration with delavirdine (4)

— Etiqueta de la FDA: Cerebyx, Pfizer Laboratories Div Pfizer Inc, vigente desde el 18 de mayo de 2025. Leer la etiqueta completa en DailyMed →

Sobredosis de Fosfenitoína

Cita de la sección «Overdosage» (sobredosis) de la etiqueta aprobada por la FDA. Se muestra en inglés. Si alguien pudo haber tomado demasiado, llame a Poison Help al 1-800-222-1222 (o al 911 en una emergencia).

Nausea, vomiting, lethargy, tachycardia, bradycardia, asystole, cardiac arrest, hypotension, syncope, hypocalcemia, metabolic acidosis, and death have been reported in cases of overdosage with CEREBYX. Because CEREBYX is a prodrug of phenytoin, the following information about phenytoin overdosage may be helpful. Initial symptoms of acute phenytoin toxicity are nystagmus, ataxia, and dysarthria.

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Other signs include tremor, hyperreflexia, lethargy, slurred speech, nausea, vomiting, coma, and hypotension. Death is caused by respiratory and circulatory depression. The lethal dose of phenytoin in adults is estimated to be 2 to 5 grams. The lethal dose in pediatrics is not known. There are marked variations among individuals with respect to serum phenytoin concentrations where toxicity occurs. Lateral gaze nystagmus usually appears at 20 µg/mL, ataxia at 30 µg/mL, and dysarthria and lethargy appear when the serum concentration is over 40 µg/mL. However, phenytoin concentrations as high as 50 µg/mL have been reported without evidence of toxicity. As much as 25 times the therapeutic phenytoin dose has been taken, resulting in serum phenytoin concentrations over 100 µg/mL, with complete recovery. Irreversible cerebellar dysfunction and atrophy have been reported after overdosage. Formate and phosphate are metabolites of CEREBYX and therefore may contribute to signs of toxicity following overdosage. Signs of formate toxicity are similar to those of methanol toxicity and are associated with severe anion-gap metabolic acidosis. Large amounts of phosphate, delivered rapidly, could potentially cause hypocalcemia with paresthesia, muscle spasms, and seizures. Ionized free calcium levels can be measured and, if low, used to guide treatment. Treatment: Treatment is nonspecific since there is no known antidote to CEREBYX or phenytoin overdosage. The adequacy of the respiratory and circulatory systems should be carefully observed, and appropriate supportive measures employed. Hemodialysis can be considered since phenytoin (the active metabolite of CEREBYX) is not completely bound to plasma proteins. Total exchange transfusion has been used in the treatment of severe intoxication in children. In acute overdosage the possibility of other CNS depressants, including alcohol, should be borne in mind.

— Etiqueta de la FDA: Cerebyx, Pfizer Laboratories Div Pfizer Inc, vigente desde el 18 de mayo de 2025. Leer la etiqueta completa en DailyMed →

Presentaciones y vía de administración

Empresas que tienen este medicamento

Empresas en el directorio NDC de la FDA: la empresa que aparece en el envase (fabricante o distribuidor), con su número de productos con receta.

• Glenmark Pharmaceuticals Inc., USA3 productos
• Pfizer Laboratories Div Pfizer Inc3 productos
• Gland Pharma Limited2 productos
• Amneal Pharmaceuticals LLC2 productos
• West-Ward Pharmaceuticals Corp2 productos
• Hikma Pharmaceuticals USA Inc.2 productos
• Fresenius Kabi USA, LLC1 producto
• Sagent Pharmaceuticals1 producto

Historial de aprobación de la FDA

• NDA: Solicitud de nuevo medicamento (NDA): así se aprueba un medicamento nuevo, normalmente de marca.
• ANDA: Solicitud abreviada (ANDA): así se aprueba una versión genérica.

Aprobaciones de genéricos (5)

• ANDA077989Hikma · 6 de agosto de 2007
• ANDA078052Fresenius Kabi USA · 6 de agosto de 2007
• ANDA078476Amneal · 18 de marzo de 2008
• ANDA078765Hikma Farmaceutica · 2 de diciembre de 2009
• ANDA214926Gland · 13 de octubre de 2023

Escasez

La lista de escasez de la FDA no incluye estos productos.

Base de datos de escasez de medicamentos de la FDA →

Retiros del mercado

De los informes de la FDA, vinculados por el código NDC del producto. Un retiro suele afectar solo a lotes concretos: revise el número de lote del envase y pregunte a su farmacéutico. No deje un medicamento por su cuenta.

1. 2 de mayo de 2014 · Clase II · Cerrado por la FDA · D-1429-2014

   Presence of Particular Matter: Potential glass delamination and consistent with glass particulates observed in sample vials.

   Fosphenytoin Sodium Injection, USP, 500 mg PE/10 mL (50 mg PE/mL), (PE= phenytoin sodium equivalents) 10 mL Single Use Vial, Rx only, Manufactured for APP Fresenius Kabi USA, LLC Lake Zurich, IL 60047, NDC 63323-403-10 — Fresenius Kabi USA, LLC

2. 2 de mayo de 2014 · Clase II · Cerrado por la FDA · D-1428-2014

   Presence of Particular Matter: Potential glass delamination and consistent with glass particulates observed in sample vials.

   Fosphenytoin Sodium Injection, USP, 100 mg PE/2 mL (50 mg PE/mL) (PE= phenytoin sodium equivalents) 2 mL Single Use Vial, Rx only, Manufactured for APP Fresenius Kabi USA, LLC Lake Zurich, IL 60047, NDC 63323-403-02 — Fresenius Kabi USA, LLC

3. 13 de abril de 2012 · Clase II · Cerrado por la FDA · D-1437-2012

   Presence of Particulate Matter: This product is being recalled due to the discovery of particles in the stability samples and retain samples.

   Fosphenytoin Sodium Injection, USP, 100 mg PE per 2 mL (50 mg PE per mL), 2 mL Single Dose Vial, packaged in 25-count x 2 mL Single Dose Vials per carton, Rx only, Mfd. By: Hikma Farmaceutica (Portugal), S.A.; Dist. By: — West-ward Pharmaceutical Corp.

4. 13 de abril de 2012 · Clase II · Cerrado por la FDA · D-1438-2012

   Presence of Particulate Matter: This product is being recalled due to the discovery of particles in the stability samples and retain samples.

   Fosphenytoin Sodium Injection, USP, 500 mg PE per 10 mL (50 mg PE per mL), 10 mL Single Dose Vial, packaged in 10-count x 10 mL Single Dose Vials per carton, Rx only, Mfd. By: Hikma Farmaceutica (Portugal), S.A.; Dist. B — West-ward Pharmaceutical Corp.

Identificadores oficiales

Siguientes pasos

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• Últimos retiros de medicamentos de la FDATodos los medicamentos, los más recientes primero
• CerebyxPágina de marca: productos, fabricante y precio
• Glenmark Pharmaceuticals Inc., USAFabricante o distribuidor
• Pfizer Laboratories Div Pfizer IncFabricante o distribuidor
• Gland Pharma LimitedFabricante o distribuidor
• Todos los medicamentos con receta de la A a la ZBusque por nombre genérico, de marca o en español

Fuentes

1. Etiqueta aprobada por la FDA en DailyMed (Biblioteca Nacional de Medicina) — Cerebyx, Pfizer Laboratories Div Pfizer Inc, vigente desde el 18 de mayo de 2025; vía openFDA, datos de la FDA exportados el 30 de octubre de 2026, consultados el 31 de octubre de 2026
2. NDC Directory (openFDA) — Administración de Alimentos y Medicamentos de los EE. UU. (FDA), datos de la FDA exportados el 30 de octubre de 2026, consultados el 31 de octubre de 2026
3. Drugs@FDA (openFDA) — Administración de Alimentos y Medicamentos de los EE. UU. (FDA), datos de la FDA exportados el 30 de octubre de 2026, consultados el 31 de octubre de 2026
4. Drug recall enforcement reports (openFDA) — Administración de Alimentos y Medicamentos de los EE. UU. (FDA), datos de la FDA exportados el 27 de octubre de 2026, consultados el 31 de octubre de 2026
5. Drug shortages (openFDA) — Administración de Alimentos y Medicamentos de los EE. UU. (FDA), datos de la FDA exportados el 30 de octubre de 2026, consultados el 31 de octubre de 2026
6. Nombre en español: RxNorm (Biblioteca Nacional de Medicina de EE. UU.) y Wikidata, vinculados por el identificador RxNorm (RxCUI) del principio activo, sin coincidencias aproximadas.

La FDA ofrece los datos de openFDA tal cual; pueden estar incompletos. Guíese siempre por la etiqueta que viene con su medicamento. Buscador de informes de retiros de la FDA →

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