Prescription medicine
Fosphenytoin Brand names: Cerebyx
Fosphenytoin (Cerebyx) is a prescription medicine with an FDA approval on record since 1996. FDA's NDC Directory lists it from 7 generic labelers.
- Generic listed
- Boxed warning
Check it at the source: the fosphenytoin FDA label on DailyMed (effective May 18, 2025, Pfizer Laboratories Div Pfizer Inc); the NDA 20450 record on Drugs@FDA; every fosphenytoin label on DailyMed.
Highlights of the record
FDA label of May 18, 2025; NDC Directory, Drugs@FDA and Orange Book, October 8, 2026
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. 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 ).
Used for
From the label: indications and usageCEREBYX is indicated for the treatment of generalized tonic-clonic status epilepticus and prevention and treatment of seizures occurring during neurosurgery.
Forms and strengths
- 50 mg/ml
Injection (solution); injection.
On the market
- Earliest approval on file
- August 5, 1996 Cerebyx, Parke Davis; Drugs@FDA’s file, where older or withdrawn approvals can be missing
- Generic approvals
- 14 first August 6, 2007; 7 with a marketed status in Drugs@FDA
- Labelers listed (NDC)
- 8 of which 7 under generic applications, 1 under brand applications, repackagers included
- Last listed patent
- February 27, 2033 Sesquient injection; not a generic launch date
Supply and safety
- Pharmacy cost (NADAC)
- Not in the survey
- Shortage (FDA)
- No current entry
- Recalls by its makers (FDA)
- 6 since 2012 0 Class I among all firms' recalls; latest December 15, 2017
- FAERS reports
- 2,553 through July 30, 2026
What is fosphenytoin used for?
From the label: indications and usageCEREBYX 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 [see Dosage and Administration (2.4) and Warnings and Precautions (5.2) ]. 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, as short-term use, for oral phenytoin. CEREBYX should be used only when oral phenytoin administration is not possible.
Conditions named in the indications of fosphenytoin's FDA labels, with every medicine labeled for each:
FDA pharmacologic class: Anti-epileptic Agent.
Source: FDA drug label (CEREBYX), NDA020450 (Parke Davis), as published by Pfizer Laboratories Div Pfizer Inc, effective May 18, 2025 (SPL set de5a6711-4abb-4c3d-a18b-266b094ace11), via openFDA; the full label on DailyMed
Is there a generic for fosphenytoin (Cerebyx)?
The FDA approved the first generic fosphenytoin on August 6, 2007. 14 generic applications are approved; 7 of them carry a current (not discontinued) marketing status in Drugs@FDA; that status is not evidence that the generic is on sale.
FDA's NDC Directory lists fosphenytoin from 7 labelers under a generic (ANDA) application and from 1 brand labeler. A listing means the company has registered the product for sale; it does not show that every pharmacy stocks it.
The Orange Book lists no patent for Cerebyx injection; a patent listed only for Sesquient injection runs to February 27, 2033. A patent or exclusivity date is not the date a generic goes on sale: court cases and settlements move it either way.
- 1996 earliest approval on file
- 2007 first generic approved
- 2033 last listed patent
- red ticks recalls
Source: Drugs@FDA, FDA NDC Directory and the Orange Book (openFDA bulk files, October 8, 2026)
Has fosphenytoin been recalled?
The FDA's Enforcement Report lists 6 recalls naming fosphenytoin since 2012: 0 Class I (the most serious), 6 Class II, 0 Class III; 0 still ongoing. A recall names products and lots, not every product of the medicine.
| Started | Class | Company | Reason |
|---|---|---|---|
| December 15, 2017 | Class II | Amneal Pharmaceuticals | Presence of particulate matter |
| August 31, 2017 | Class II | Amneal Pharmaceuticals LLC | Presence of Particulate Matter |
| May 2, 2014 | Class II | Fresenius Kabi USA, LLC | Presence of Particular Matter: Potential glass delamination and consistent with glass particulates observed in sample vials. |
| April 13, 2012 | Class II | West-ward Pharmaceutical Corp. | Presence of Particulate Matter: This product is being recalled due to the discovery of particles in the stability samples and retain samples. |
Source: FDA Enforcement Report (drug recalls) via openFDA, through October 8, 2026
What does the fosphenytoin label say about other medicines?
The fosphenytoin label names 79 other medicines in its interaction, contraindication or warning sections. The labels of 4 other medicines name fosphenytoin. The sentences are the labels' own; a label lists what its studies and reports found, not every interaction.
| Medicine named | Section | What the label says |
|---|---|---|
| Albendazole | drug interactions | Interacting Agent: Other; Examples: Albendazole (decreases active metabolite), chlorpropamide, clozapine, cyclosporine, digoxin, disopyramide, folic acid, methadone, mexiletine, praziquantel, quetiapine |
| Amiodarone | drug interactions | Interacting Agent: Other; Examples: Acute alcohol intake, amiodarone, chloramphenicol, chlordiazepoxide, disulfiram, estrogen, fluvastatin, isoniazid, methylphenidate, phenothiazines, salicylates, ticlopidine, tolbutamide, trazodone, warfarin |
| Apixaban | drug interactions | Interacting Agent: Anticoagulants; Examples: Apixaban, dabigatran, edoxaban, rivaroxaban |
| Atorvastatin | drug interactions | Interacting Agent: Antilipidemic agents; Examples: Atorvastatin, fluvastatin, simvastatin |
| Bleomycin | drug interactions | Interacting Agent: Antineoplastic agents usually in combination; Examples: Bleomycin, carboplatin, cisplatin, doxorubicin, methotrexate |
| Capecitabine | drug interactions | Interacting Agent: Antineoplastic agents; Examples: Capecitabine, fluorouracil |
| Carbamazepine | drug interactions | Interacting Agent: Antiepileptic drugs; Examples: Carbamazepine, vigabatrin |
| Carboplatin | drug interactions | Interacting Agent: Antineoplastic agents usually in combination; Examples: Bleomycin, carboplatin, cisplatin, doxorubicin, methotrexate |
| Chloramphenicol | drug interactions | Interacting Agent: Other; Examples: Acute alcohol intake, amiodarone, chloramphenicol, chlordiazepoxide, disulfiram, estrogen, fluvastatin, isoniazid, methylphenidate, phenothiazines, salicylates, ticlopidine, tolbutamide, trazodone, warfarin |
| Chlordiazepoxide | drug interactions | Interacting Agent: Other; Examples: Acute alcohol intake, amiodarone, chloramphenicol, chlordiazepoxide, disulfiram, estrogen, fluvastatin, isoniazid, methylphenidate, phenothiazines, salicylates, ticlopidine, tolbutamide, trazodone, warfarin |
| Cimetidine | drug interactions | Interacting Agent: Gastric acid reducing agents; Examples: H 2 antagonists (cimetidine), omeprazole |
| Cisatracurium | drug interactions | Interacting Agent: Neuromuscular blocking agents; Examples: Cisatracurium, pancuronium, rocuronium and vecuronium: resistance to the neuromuscular blocking action of the nondepolarizing neuromuscular blocking agents has occurred in patients chronically administered phenytoin. … |
| Cisplatin | drug interactions | Interacting Agent: Antineoplastic agents usually in combination; Examples: Bleomycin, carboplatin, cisplatin, doxorubicin, methotrexate |
| Clozapine | drug interactions | Interacting Agent: Other; Examples: Albendazole (decreases active metabolite), chlorpropamide, clozapine, cyclosporine, digoxin, disopyramide, folic acid, methadone, mexiletine, praziquantel, quetiapine |
Every other medicine the fosphenytoin label names
| Medicine named | Section | What the label says |
|---|---|---|
| Cyclosporine | drug interactions | Interacting Agent: Other; Examples: Albendazole (decreases active metabolite), chlorpropamide, clozapine, cyclosporine, digoxin, disopyramide, folic acid, methadone, mexiletine, praziquantel … |
| Dabigatran | drug interactions | Interacting Agent: Anticoagulants; Examples: Apixaban, dabigatran, edoxaban, rivaroxaban |
| Diazepam | drug interactions | Interacting Agent: Other; Examples: Chronic alcohol abuse, diazepam, diazoxide, folic acid, reserpine, rifampin, St. John's wort, The induction potency of St. … |
| Diazoxide | drug interactions | Interacting Agent: Other; Examples: Chronic alcohol abuse, diazepam, diazoxide, folic acid, reserpine, rifampin, St. John's wort, The induction potency of St. … |
| Digoxin | drug interactions | Interacting Agent: Other; Examples: Albendazole (decreases active metabolite), chlorpropamide, clozapine, cyclosporine, digoxin, disopyramide, folic acid, methadone, mexiletine, praziquantel … |
| Disopyramide | drug interactions | Interacting Agent: Other; Examples: Albendazole (decreases active metabolite), chlorpropamide, clozapine, cyclosporine, digoxin, disopyramide, folic acid, methadone, mexiletine, praziquantel … |
| Disulfiram | drug interactions | Interacting Agent: Other; Examples: Acute alcohol intake, amiodarone, chloramphenicol, chlordiazepoxide, disulfiram, estrogen, fluvastatin, isoniazid, methylphenidate, phenothiazines, salicylates … |
| Divalproex | drug interactions | Drugs That Affect Phenytoin Concentrations Interacting Agent Examples Drugs that may increase phenytoin serum levels Antiepileptic drugs Ethosuximide, felbamate, oxcarbazepine, methsuximide … |
| Doxorubicin | drug interactions | Interacting Agent: Antineoplastic agents usually in combination; Examples: Bleomycin, carboplatin, cisplatin, doxorubicin, methotrexate |
| Doxycycline | drug interactions | Interacting Agent: Other; Examples: Corticosteroids, doxycycline, estrogens, furosemide, oral contraceptives, paroxetine, quinidine, rifampin, sertraline, theophylline, and vitamin D |
| Edoxaban | drug interactions | Interacting Agent: Anticoagulants; Examples: Apixaban, dabigatran, edoxaban, rivaroxaban |
| Efavirenz | drug interactions | Interacting Agent: Antiviral agents; Examples: Efavirenz, lopinavir/ritonavir, indinavir, nelfinavir, ritonavir, saquinavir Fosamprenavir: phenytoin when given with fosamprenavir alone may decrease … |
| Ethosuximide | drug interactions | Interacting Agent: Antiepileptic drugs; Examples: Ethosuximide, felbamate, oxcarbazepine, methsuximide, topiramate |
| Felbamate | drug interactions | Interacting Agent: Antiepileptic drugs; Examples: Ethosuximide, felbamate, oxcarbazepine, methsuximide, topiramate |
| Fluconazole | drug interactions | Interacting Agent: Azoles; Examples: Fluconazole, ketoconazole, itraconazole, miconazole, voriconazole |
| Fluorouracil | drug interactions | Interacting Agent: Antineoplastic agents; Examples: Capecitabine, fluorouracil |
| Fluoxetine | drug interactions | Interacting Agent: Antidepressants; Examples: Fluoxetine, fluvoxamine, sertraline |
| Fluvastatin | drug interactions | Interacting Agent: Other; Examples: Acute alcohol intake, amiodarone, chloramphenicol, chlordiazepoxide, disulfiram, estrogen, fluvastatin, isoniazid, methylphenidate, phenothiazines, salicylates … |
| Fluvoxamine | drug interactions | Interacting Agent: Antidepressants; Examples: Fluoxetine, fluvoxamine, sertraline |
| Fosamprenavir | drug interactions | Interacting Agent: Antiviral agents; Examples: Fosamprenavir, nelfinavir, ritonavir |
| Furosemide | drug interactions | Interacting Agent: Other; Examples: Corticosteroids, doxycycline, estrogens, furosemide, oral contraceptives, paroxetine, quinidine, rifampin, sertraline, theophylline, and vitamin D |
| Irinotecan | drug interactions | Interacting Agent: Antineoplastic agents; Examples: Irinotecan, paclitaxel, teniposide |
| Isoniazid | drug interactions | Interacting Agent: Other; Examples: Acute alcohol intake, amiodarone, chloramphenicol, chlordiazepoxide, disulfiram, estrogen, fluvastatin, isoniazid, methylphenidate, phenothiazines, salicylates … |
| Itraconazole | drug interactions | Interacting Agent: Azoles; Examples: Fluconazole, ketoconazole, itraconazole, miconazole, voriconazole |
| Ketoconazole | drug interactions | Interacting Agent: Azoles; Examples: Fluconazole, ketoconazole, itraconazole, miconazole, voriconazole |
| Lacosamide | drug interactions | … Carbamazepine, felbamate, lamotrigine, topiramate, oxcarbazepine, lacosamide |
| Lamotrigine | drug interactions | … serum levels is unpredictable.; Examples: Carbamazepine, felbamate, lamotrigine, topiramate, oxcarbazepine, lacosamide |
| Lopinavir and ritonavir | drug interactions | Carbamazepine, felbamate, lamotrigine, topiramate, oxcarbazepine, lacosamide Antilipidemic agents Atorvastatin, fluvastatin, simvastatin Antiplatelets Ticagrelor Antiviral agents Efavirenz … |
| Methadone | drug interactions | … chlorpropamide, clozapine, cyclosporine, digoxin, disopyramide, folic acid, methadone, mexiletine, praziquantel, quetiapine |
| Methotrexate | drug interactions | Interacting Agent: Antineoplastic agents usually in combination; Examples: Bleomycin, carboplatin, cisplatin, doxorubicin, methotrexate |
| Methsuximide | drug interactions | Interacting Agent: Antiepileptic drugs; Examples: Ethosuximide, felbamate, oxcarbazepine, methsuximide, topiramate |
| Methylphenidate | drug interactions | … chloramphenicol, chlordiazepoxide, disulfiram, estrogen, fluvastatin, isoniazid, methylphenidate, phenothiazines, salicylates, ticlopidine, tolbutamide, trazodone, warfarin |
| Mexiletine | drug interactions | … clozapine, cyclosporine, digoxin, disopyramide, folic acid, methadone, mexiletine, praziquantel, quetiapine |
| Miconazole | drug interactions | Interacting Agent: Azoles; Examples: Fluconazole, ketoconazole, itraconazole, miconazole, voriconazole |
| Nelfinavir | drug interactions | Interacting Agent: Antiviral agents; Examples: Fosamprenavir, nelfinavir, ritonavir |
| Nifedipine | drug interactions | Interacting Agent: Calcium channel blockers; Examples: Nifedipine, nimodipine, nisoldipine, verapamil |
| Nimodipine | drug interactions | Interacting Agent: Calcium channel blockers; Examples: Nifedipine, nimodipine, nisoldipine, verapamil |
| Nisoldipine | drug interactions | Interacting Agent: Calcium channel blockers; Examples: Nifedipine, nimodipine, nisoldipine, verapamil |
| Omeprazole | drug interactions | Interacting Agent: Gastric acid reducing agents; Examples: H 2 antagonists (cimetidine), omeprazole |
| Oxcarbazepine | drug interactions | Interacting Agent: Antiepileptic drugs; Examples: Ethosuximide, felbamate, oxcarbazepine, methsuximide, topiramate |
| Paclitaxel | drug interactions | Interacting Agent: Antineoplastic agents; Examples: Irinotecan, paclitaxel, teniposide |
| Paroxetine | drug interactions | Interacting Agent: Other; Examples: Corticosteroids, doxycycline, estrogens, furosemide, oral contraceptives, paroxetine, quinidine, rifampin, sertraline, theophylline, and vitamin D |
| Phenobarbital | drug interactions | Interacting Agent: Antiepileptic drugs; Examples: Phenobarbital, valproate sodium, valproic acid |
| Phenytoin | boxed 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 … |
| Posaconazole | drug interactions | Interacting Agent: Azoles; Examples: Fluconazole, ketoconazole, itraconazole, posaconazole, voriconazole |
| Praziquantel | drug interactions | … cyclosporine, digoxin, disopyramide, folic acid, methadone, mexiletine, praziquantel, quetiapine |
| Quetiapine | drug interactions | … digoxin, disopyramide, folic acid, methadone, mexiletine, praziquantel, quetiapine |
| Quinidine | drug interactions | Interacting Agent: Other; Examples: Corticosteroids, doxycycline, estrogens, furosemide, oral contraceptives, paroxetine, quinidine, rifampin, sertraline, theophylline, and vitamin D |
| Rifampin | drug interactions | Interacting Agent: Other; Examples: Chronic alcohol abuse, diazepam, diazoxide, folic acid, reserpine, rifampin, St. John's wort, The induction potency of St. … |
| Ritonavir | drug interactions | Interacting Agent: Antiviral agents; Examples: Fosamprenavir, nelfinavir, ritonavir |
| Rivaroxaban | drug interactions | Interacting Agent: Anticoagulants; Examples: Apixaban, dabigatran, edoxaban, rivaroxaban |
| Rocuronium | drug interactions | Interacting Agent: Neuromuscular blocking agents; Examples: Cisatracurium, pancuronium, rocuronium and vecuronium: resistance to the neuromuscular blocking action of the nondepolarizing neuromuscular … |
| Sertraline | drug interactions | Interacting Agent: Antidepressants; Examples: Fluoxetine, fluvoxamine, sertraline |
| Simvastatin | drug interactions | Interacting Agent: Antilipidemic agents; Examples: Atorvastatin, fluvastatin, simvastatin |
| Sulfadiazine | drug interactions | Interacting Agent: Sulfonamides; Examples: Sulfamethizole, sulfaphenazole, sulfadiazine, sulfamethoxazole-trimethoprim |
| Theophylline | drug interactions | … induction potency of St. John's wort may vary widely based on preparation. theophylline |
| Ticagrelor | drug interactions | Interacting Agent: Antiplatelets; Examples: Ticagrelor |
| Topiramate | drug interactions | Interacting Agent: Antiepileptic drugs; Examples: Ethosuximide, felbamate, oxcarbazepine, methsuximide, topiramate |
| Trazodone | drug interactions | … methylphenidate, phenothiazines, salicylates, ticlopidine, tolbutamide, trazodone, warfarin |
| Valproic acid | drug interactions | Interacting Agent: Antiepileptic drugs; Examples: Phenobarbital, valproate sodium, valproic acid |
| Vecuronium | drug interactions | Interacting Agent: Neuromuscular blocking agents; Examples: Cisatracurium, pancuronium, rocuronium and vecuronium: resistance to the neuromuscular blocking action of the nondepolarizing neuromuscular … |
| Verapamil | drug interactions | Interacting Agent: Calcium channel blockers; Examples: Nifedipine, nimodipine, nisoldipine, verapamil |
| Vigabatrin | drug interactions | Interacting Agent: Antiepileptic drugs; Examples: Carbamazepine, vigabatrin |
| Voriconazole | drug interactions | Interacting Agent: Azoles; Examples: Fluconazole, ketoconazole, itraconazole, miconazole, voriconazole |
| Warfarin | drug interactions | … phenothiazines, salicylates, ticlopidine, tolbutamide, trazodone, warfarin |
Other labels that name fosphenytoin
Source: FDA drug label (CEREBYX), NDA020450 (Parke Davis), as published by Pfizer Laboratories Div Pfizer Inc, effective May 18, 2025 (SPL set de5a6711-4abb-4c3d-a18b-266b094ace11), via openFDA; the full label on DailyMed
What do FAERS reports show for fosphenytoin?
The FDA Adverse Event Reporting System holds 2,553 reports that list fosphenytoin among the medicines taken, through July 30, 2026, each a report of something that happened, not proof the medicine caused it; 354 are coded as a death and 1,162 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is.
Reports received each year
The most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026
How does fosphenytoin compare with medicines for the same use?
1 side-by-side page set fosphenytoin beside a medicine whose label shares a use: approvals, generics, pharmacy cost, warnings and supply.
What next?
- Other anti-seizure medicines
- the pharmacologic class, with prices and generics
- Fosphenytoin side effects
- the label's list beside FAERS reports
- Check an interaction
- what two or more labels say about each other