Fosphenytoin (Injection route)

Pronunciation:

fos-FEN-i-toin

Brand Names:

Cerebyx

Dosage Forms:

Solution

Warnings:

Injection route(Solution)

The rate of IV fosphenytoin sodium 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 IV fosphenytoin sodium. 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 .

Classifications:

Therapeutic—

Anticonvulsant

Chemical—

Hydantoin (class)

Uses of This Medicine:

Fosphenytoin injection is used to control certain types of seizures (convulsions) in the treatment of epilepsy. It is also used to prevent and treat seizures that occur during brain surgery. This medicine is an anticonvulsant that works in the brain tissue to stop seizures.

Fosphenytoin injection also used for short-term substitution for oral phenytoin. This medicine should only be used when taking phenytoin by mouth is not possible.

This medicine is to be given only by or under the direct supervision of a doctor.

Before Using This Medicine:

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies—

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Children—

Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of Cerebyx® injection in children.

Appropriate studies have not been performed on the relationship of age to the effects of fosphenytoin injection in the pediatric population. Safety and efficacy have not been established.

Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of Sesquient™ injection for short-term substitution for oral phenytoin in children 2 years of age and older. Safety and efficacy have been established.

Older adults—

Appropriate studies on the relationship of age to the effects of fosphenytoin injection have not been performed in the geriatric population. However, elderly patients are more likely to have age-related liver, kidney, or heart problems, which may require caution and an adjustment in the dose for patients receiving fosphenytoin injection.

Breast-feeding—

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Other medicines—

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are receiving this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

Artemether
Atazanavir
Bepridil
Boceprevir
Cisapride
Cobicistat
Daclatasvir
Darunavir
Dasabuvir
Delamanid
Delavirdine
Doravirine
Dronedarone
Elbasvir
Elvitegravir
Fostemsavir
Grazoprevir
Isavuconazonium Sulfate
Lenacapavir
Levoketoconazole
Lorlatinib
Lurasidone
Maraviroc
Mavacamten
Mesoridazine
Nirmatrelvir
Ombitasvir
Pacritinib
Paritaprevir
Pimozide
Piperaquine
Praziquantel
Ranolazine
Rilpivirine
Ritonavir
Sparfloxacin
Telaprevir
Tenofovir Alafenamide
Terfenadine
Thioridazine
Ziprasidone

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Abemaciclib
Abiraterone Acetate
Acalabrutinib
Adagrasib
Afatinib
Alfentanil
Alpelisib
Amiodarone
Amisulpride
Anagrelide
Apazone
Apixaban
Apomorphine
Apremilast
Aprepitant
Aripiprazole
Arsenic Trioxide
Asciminib
Aspirin
Atogepant
Avacopan
Avapritinib
Axitinib
Beclamide
Bedaquiline
Belumosudil
Bendamustine
Benzhydrocodone
Berotralstat
Betrixaban
Bictegravir
Bortezomib
Bosutinib
Brexpiprazole
Brigatinib
Buprenorphine
Bupropion
Buserelin
Cabozantinib
Calcifediol
Cannabidiol
Capecitabine
Capivasertib
Capmatinib
Carbamazepine
Cariprazine
Cenobamate
Ceritinib
Chloroquine
Chlorpheniramine
Cisatracurium
Citalopram
Clarithromycin
Clofazimine
Clothiapine
Clozapine
Cobimetinib
Codeine
Copanlisib
Crizotinib
Cyclophosphamide
Cyclosporine
Dabigatran Etexilate
Dabrafenib
Daridorexant
Darolutamide
Dasatinib
Deferasirox
Deflazacort
Degarelix
Deslorelin
Desogestrel
Deutetrabenazine
Dexamethasone
Dexmedetomidine
Diazepam
Diazoxide
Dienogest
Dihydrocodeine
Dolutegravir
Domperidone
Donepezil
Dopamine
Doxifluridine
Doxorubicin
Doxorubicin Hydrochloride Liposome
Drospirenone
Duvelisib
Edoxaban
Efavirenz
Elacestrant
Elexacaftor
Eliglustat
Enasidenib
Encorafenib
Entrectinib
Enzalutamide
Eravacycline
Erdafitinib
Erlotinib
Escitalopram
Eslicarbazepine Acetate
Estetrol
Estradiol
Ethinyl Estradiol
Ethosuximide
Ethynodiol
Etonogestrel
Etrasimod
Etravirine
Everolimus
Exemestane
Ezogabine
Fedratinib
Fenfluramine
Fentanyl
Fexinidazole
Finerenone
Fingolimod
Fluconazole
Fluorouracil
Fluoxetine
Fluvastatin
Formoterol
Fosaprepitant
Foscarnet
Fosnetupitant
Fostamatinib
Fruquintinib
Futibatinib
Gefitinib
Gepirone
Gestodene
Gilteritinib
Glasdegib
Glecaprevir
Gonadorelin
Goserelin
Halothane
Hemin
Histrelin
Hydrocodone
Hydroxychloroquine
Hydroxyzine
Ibrexafungerp
Ibrutinib
Idelalisib
Ifosfamide
Imatinib
Infigratinib
Infliximab
Inotuzumab Ozogamicin
Irinotecan
Irinotecan Liposome
Istradefylline
Itraconazole
Ivabradine
Ivacaftor
Ivosidenib
Ixabepilone
Ixazomib
Ketoconazole
Lamotrigine
Lapatinib
Larotrectinib
Ledipasvir
Lefamulin
Lemborexant
Leniolisib
Lenvatinib
Letermovir
Leuprolide
Levofloxacin
Levoleucovorin
Levonorgestrel
Lidocaine
Linagliptin
Lofexidine
Lopinavir
Lumateperone
Lurbinectedin
Macimorelin
Macitentan
Manidipine
Maribavir
Medroxyprogesterone
Meperidine
Mestranol
Methadone
Methotrexate
Methylphenidate
Metronidazole
Miconazole
Midostaurin
Mifepristone
Mirtazapine
Mitapivat
Mobocertinib
Moxifloxacin
Nafarelin
Naloxegol
Neratinib
Netupitant
Nifedipine
Nilotinib
Nimodipine
Nintedanib
Nirogacestat
Nitisinone
Nomegestrol
Norelgestromin
Norethindrone
Norgestimate
Norgestrel
Olanzapine
Olaparib
Oliceridine
Olutasidenib
Omaveloxolone
Omeprazole
Ondansetron
Orlistat
Osilodrostat
Osimertinib
Oxaliplatin
Oxcarbazepine
Oxycodone
Ozanimod
Paclitaxel
Palbociclib
Paliperidone
Palovarotene
Panobinostat
Paroxetine
Pasireotide
Pazopanib
Pemigatinib
Pentazocine
Perampanel
Pexidartinib
Phenobarbital
Pibrentasvir
Pimavanserin
Pirtobrutinib
Pitolisant
Ponatinib
Ponesimod
Posaconazole
Pralsetinib
Pretomanid
Primidone
Quetiapine
Quizartinib
Regorafenib
Relugolix
Repotrectinib
Reserpine
Ribociclib
Rifampin
Rimegepant
Ripretinib
Risperidone
Ritlecitinib
Rivaroxaban
Rocuronium
Roflumilast
Rolapitant
Romidepsin
Ruxolitinib
Samidorphan
Saquinavir
Segesterone
Selpercatinib
Selumetinib
Sertraline
Sevoflurane
Sildenafil
Simeprevir
Siponimod
Sirolimus Protein-Bound
Sofosbuvir
Solifenacin
Sonidegib
Sorafenib
Sotalol
Sotorasib
Sparsentan
Stiripentol
St John's Wort
Sufentanil
Sulfamethoxazole
Sulpiride
Sunitinib
Tacrolimus
Tamoxifen
Tasimelteon
Tazemetostat
Tegafur
Temsirolimus
Tezacaftor
Theophylline
Thiotepa
Ticagrelor
Tivozanib
Tocilizumab
Tofacitinib
Tolvaptan
Topiramate
Trabectedin
Tramadol
Trazodone
Triclabendazole
Trimethoprim
Triptorelin
Tucatinib
Ubrogepant
Ulipristal
Upadacitinib
Valbenazine
Valproic Acid
Vandetanib
Velpatasvir
Vemurafenib
Venetoclax
Venlafaxine
Vilanterol
Vilazodone
Vincristine
Vincristine Sulfate Liposome
Vinflunine
Voclosporin
Vonoprazan
Vorapaxar
Voriconazole
Vortioxetine
Voxelotor
Voxilaprevir
Zanubrutinib
Zolpidem
Zuclopenthixol
Zuranolone

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Acetaminophen
Acetazolamide
Acyclovir
Amitriptyline
Amprenavir
Atorvastatin
Betamethasone
Bexarotene
Bleomycin
Busulfan
Carboplatin
Caspofungin
Chloramphenicol
Cimetidine
Ciprofloxacin
Cisplatin
Clobazam
Clopidogrel
Cortisone
Dicumarol
Digitoxin
Diltiazem
Disopyramide
Disulfiram
Doxepin
Felbamate
Fludrocortisone
Fluvoxamine
Folic Acid
Fosamprenavir
Ginkgo
Imipramine
Isoniazid
Levodopa
Levomethadyl
Levothyroxine
Methoxsalen
Methsuximide
Midazolam
Nafimidone
Nelfinavir
Nilutamide
Nisoldipine
Ospemifene
Pancuronium
Phenprocoumon
Piperine
Prednisolone
Prednisone
Progabide
Quinidine
Quinine
Remacemide
Rufinamide
Sabeluzole
Shankhapulshpi
Simvastatin
Sirolimus
Sulfamethizole
Sulfaphenazole
Sulthiame
Telithromycin
Tenidap
Tiagabine
Ticlopidine
Ticrynafen
Tirilazad
Tizanidine
Tolbutamide
Triamcinolone
Tubocurarine
Valacyclovir
Vecuronium
Verapamil
Vigabatrin
Viloxazine

Other interactions—

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following may cause an increased risk of certain side effects but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco.

Ethanol

Other medical problems—

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

Blood or bone marrow problems (eg, agranulocytosis, leukopenia, or thrombocytopenia) or
Diabetes or
Heart failure or
Hypotension (low blood pressure) or
Lymphadenopathy (lymph node problems) or
Porphyria (an enzyme problem)—Use with caution. May make these conditions worse.

Heart block (eg, Adams-Stokes syndrome, AV block, or sinoatrial block) or
Liver problems from using fosphenytoin or phenytoin, history of or
Sinus bradycardia (slow heartbeat)—Should not be used in patients with these conditions.

Hypoalbuminemia (low albumin in the blood) or
Kidney disease or
Liver disease—Use with caution. The effects may be increased because of slower removal from the body.

Proper Use of This Medicine:

A nurse or other trained health professional will give you this medicine in a hospital. This medicine is given as a shot into one of your muscles or through a needle placed in one of your veins.

Your doctor will only give you a few doses of this medicine until your condition improves. You will be switched to an oral medicine that works the same way. If you have any concerns about this, talk to your doctor.

Precautions While Using This Medicine:

It is very important that your doctor check your progress closely while you are receiving this medicine. This is to see if the medicine is working properly and to allow for a change in the dose. Blood tests may be needed to check for any unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using the medicine, tell your doctor right away. Your doctor may want you to join a pregnancy registry for patients taking a seizure medicine.

Do not receive this medicine while you are also taking delavirdine (Rescriptor®). Using these medicines together may cause delavirdine to not work as well for you.

This medicine may increase your risk for heart or blood vessel problems. Check with your doctor right away if you have blurred vision, chest pain, confusion, lightheadedness, dizziness, or fainting, fast or irregular heartbeat, trouble breathing, or unusual tiredness or weakness.

This medicine may cause some people to become dizzy, lightheaded, faint, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert and able to see well.

Do not stop using this medicine without first checking with your doctor. Stopping the medicine suddenly may cause your seizures to return or to occur more often.

Serious skin reactions (eg, toxic epidermal necrolysis, Stevens-Johnson syndrome, acute-generalized exanthematous pustulosis) can occur with this medicine. Check with your doctor right away if you or your child have blistering, peeling, or loose skin, chills, cough, diarrhea, itching, joint or muscle pain, red irritated eyes, red skin lesions, often with a purple center, sore throat, sores, ulcers, or white spots in the mouth or on the lips, or unusual tiredness or weakness while you are using this medicine.

Tell your doctor right away if you or your child develop a black, tarry stools, chest pain, chills, cough, fever, rash, swollen, painful, or tender lymph glands in the neck, armpit, or groin, painful or difficult urination, sore throat, sores, ulcers, or white spots on the lips or in the mouth, unusual bleeding or bruising, or yellow eyes or skin after using this medicine. These may be symptoms of a serious and life-threatening condition called drug reaction with eosinophilia and systemic symptoms (DRESS).

This medicine may cause serious allergic reactions, including angioedema. These can be life-threatening and require immediate medical attention. Tell your doctor right away if you or your child have a rash, itching, hoarseness, trouble breathing, trouble swallowing, or any swelling of your hands, face, or mouth after using this medicine.

This medicine may cause liver problems. Check with your doctor right away if you or your child have a dark-colored urine, general feeling of tiredness or weakness, headache, light-colored stools, stomach pain continuing, vomiting, or yellow eyes or skin.

Fosphenytoin can temporarily lower the number of white blood cells in your blood, increasing the chance of getting an infection. It can also lower the number of platelets, which are necessary for proper blood clotting. If this occurs, there are certain precautions you can take, especially when your blood count is low, to reduce the risk of infection or bleeding:

If you can, avoid people with infections. Check with your doctor immediately if you think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.
Check with your doctor immediately if you notice any unusual bleeding or bruising, black, tarry stools, blood in the urine or stools, or pinpoint red spots on your skin.
Be careful when using a regular toothbrush, dental floss, or toothpick. Your medical doctor, dentist, or nurse may recommend other ways to clean your teeth and gums. Check with your medical doctor before having any dental work done.
Do not touch your eyes or the inside of your nose unless you have just washed your hands and have not touched anything else in the meantime.
Be careful not to cut yourself when you are using sharp objects such as a safety razor or fingernail or toenail cutters.
Avoid contact sports or other situations where bruising or injury could occur.

Tell your doctor right away if your skin feels like it is burning, crawling, or itching, or if you have numbness, prickling, "pins and needles", or tingling feelings after receiving fosphenytoin injection.

This medicine may cause purple glove syndrome. Tell your doctor right away if you have skin discoloration, pain, or swelling at the injection site after receiving this medicine.

This medicine may affect blood sugar levels. If you notice a change in the results of your blood or urine sugar tests or if you have any questions, check with your doctor.

Birth control pills may not work while you are using this medicine. To keep from getting pregnant, use another form of birth control along with your birth control pills. Other forms include a condom, a diaphragm, or a contraceptive foam or jelly.

Avoid drinking alcohol while you are receiving this medicine.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Side Effects of This Medicine:

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur:

More common: Blurred vision; confusion; dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position; feeling of warmth or heat; flushing or redness of the skin, especially on the face and neck; headache; sweating; unusual tiredness or weakness

Less common: Anxiety; bruising; burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings; changes in patterns and rhythms of speech; dark-colored urine; difficulty with speaking; drooling; dry mouth; fast, pounding, or irregular heartbeat or pulse; hyperventilation; irritability; itching skin; lack of coordination; large, flat, blue, or purplish patches in the skin; light-colored stools; loss of balance control; muscle trembling, jerking, or stiffness; nervousness; problems with movement, walking, or speech; restlessness; seizures; shakiness in the legs, arms, hands, or feet; shuffling walk; slurred speech; stiffness of the limbs; trouble breathing; trouble with sleeping; twisting movements of the body; uncontrolled movements, especially of the face, neck, and back; unsteadiness, trembling, or other problems with muscle control or coordination; vomiting; yellow eyes or skin

Rare: Absence of or decrease in body movement; aggressive or angry; agitation; black, tarry stools; bleeding gums; bleeding, blistering, burning, coldness, discoloration of the skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site; blistering, burning, crusting, dryness, or flaking of the skin; blood in the urine or stools; bloody nose; bluish color of the fingernails, lips, skin, palms, or nail beds; body aches or pain; bone pain; burning while urinating; change in consciousness; change in personality; change in the ability to see colors, especially blue or yellow; change in the color of the treated skin; chest pain, discomfort, or tightness; cloudy urine; cold, clammy skin; congestion; cough or hoarseness; cough producing mucus; coughing or spitting up blood; crying; decrease in frequency of urination; decrease in the amount of urine; deep or fast breathing with dizziness; delusions; dementia; depression; diarrhea; difficulty in passing urine (dribbling); difficulty with breathing; difficulty with moving; difficulty with swallowing; dilated neck veins; dizziness, fainting, or lightheadedness; drowsiness; dryness or soreness of the throat; dysphoria; euphoria; eye pain; feeling of unreality; feeling that others are watching you or controlling your behavior; feeling that others can hear your thoughts; feeling, seeing, or hearing things that are not there; fever or chills; flushed, dry skin; frequent urination; fruit-like breath odor; general feeling of discomfort or illness; general physical wasting or malnutrition associated with severe illness; greatly increased frequency of urination or amount of urine; headache, severe and throbbing; hives or welts; inability to move the legs or arms; inability to sit still; increase in body movements; increase in heart rate; increased hunger; increased sensitivity of the skin to sunlight; increased thirst; increased urination; increased volume of pale, dilute urine; increased watering of the mouth; irregular breathing; itching, scaling, severe redness, soreness, or swelling of the skin; joint pain; leg cramps; loss of appetite; loss of bladder control; loss of consciousness; loss of memory; loss of strength or energy; lower back or side pain; muscle aches, pains, or stiffness; muscle twitching or jerking; muscular tenderness, wasting, or weakness; nausea or vomiting; need to keep moving; no blood pressure or pulse; not breathing; numbness of the feet, hands, and around the mouth; numbness or tingling in the face, arms, hands, feet, or lips; pain or tenderness around the eyes and cheekbones; pale skin; paralysis of one side of the body; paranoia; pinpoint red spots on the skin; pounding in the ears; problems with memory; quick to react or overreact emotionally; rapid breathing; rapid heartbeat; rapid weight gain; rapidly changing moods; rash with flat lesions or small raised lesions on the skin; redness or other discoloration of the skin; rhythmic movement of the muscles; seizures; sense of detachment from self or body; severe constipation; severe headache; severe mood or mental changes; severe pain in the chest; severe sunburn; severe vomiting; shivering; sleeplessness; small lumps under the skin; small red or purple spots on the skin; sneezing; sores, ulcers, or white spots on the lips or in the mouth; spots on your skin resembling a blister or pimple; stiff neck; stomach pain; stopping of heart; stuffy or runny nose; sudden onset of severe breathing difficulty; sunken eyes; swelling of the face, fingers, feet, ankles, or lower legs; swelling of the tongue; swollen joints; swollen, painful, or tender lymph glands in the neck, armpit, or groin; twisting movements of body; unable to sleep; unconsciousness; uncontrolled movements, especially of the face, neck, and back; unexplained weight loss; unusual behavior; unusual bleeding or bruising; unusual weak feeling; voice changes; vomiting of blood or material that looks like coffee grounds; weakness or heaviness of the legs; weight gain; wrinkled skin

Incidence not known: Puffiness or swelling of the eyelids or around the eyes, face, lips or tongue; twitching, twisting, uncontrolled repetitive movements of the tongue, lips, face, arms, or legs

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common: Continuing ringing or buzzing or other unexplained noise in the ears; decreased awareness or responsiveness; hearing loss; severe sleepiness; sleepiness or unusual drowsiness; uncontrolled eye movements

Less common: Back pain; change in taste or bad, unusual, or unpleasant (after) taste; change in vision; double vision; feeling of constant movement of self or surroundings; impaired vision; lack or loss of strength; pelvic pain; seeing double; sensation of spinning

Rare: Acid or sour stomach; belching; bigger, dilated, or enlarged pupils (black part of eye); bloated; burning feeling in the chest or stomach; burning, dry, or itching eyes; change in color vision; difficulty having a bowel movement (stool); difficulty seeing at night; discharge, excessive tearing; ear pain; excess air or gas in the stomach or bowels; frequent urge to defecate; full feeling; heartburn; increased sense of hearing; increased sensitivity of the eyes to light; indigestion; itching of the vagina or genital area; loss of taste; pain during sexual intercourse; passing gas; redness, pain, swelling of the eye, eyelid, or inner lining of the eyelid; stomach discomfort, upset, or pain; straining while passing stool; tenderness in the stomach area; thick, white vaginal discharge with no odor or with a mild odor; transient, mild, or pleasant aromatic odor; vaginal yeast infection; weight loss

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Last Updated: 4/24/2024

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