Cerebyx: Uses, Side Effects and Dosage

What is CEREBYX used for?

CEREBYX is used in adults for short-term use (up to 5 days) when other means of phenytoin are unavailable, cannot be used, or do not work well enough to:

• control seizures that last more than five minutes or longer; and
• prevent and treat seizures during neurosurgery.

How does CEREBYX work?

CEREBYX contains the medicinal ingredient fosphenytoin sodium and belongs to a group of medicines called antiepileptic agents. In the body, fosphenytoin sodium is converted into phenytoin. Phenytoin works to reduce the electrical activity in the brain that causes seizures.

What are the ingredients in CEREBYX?

Medicinal ingredient: fosphenytoin sodium

Non-medicinal ingredients: hydrochloric acid, tromethamine buffer, and water for injection.

CEREBYX comes in the following dosage forms:

Solution: 75 mg of fosphenytoin sodium (as fosphenytoin sodium heptahydrate), which is equivalent to 50 mg of phenytoin sodium.

Do not use CEREBYX if:

• you are allergic to any of the following:

  • fosphenytoin sodium or any of the other ingredients in CEREBYX; and
  • phenytoins and hydantoins, medicines used to treat seizures.

If you are unsure, ask your healthcare professional.

Serious Warnings and Precautions

• you have a serious heart rhythm disorder (e.g., sinus bradycardia, sino-atrial block, second- or third-degree atrioventricular (AV) block, or Adams-Stokes syndrome).
• you are taking delavirdine, a medicine used to treat human immunodeficiency virus (HIV).

To help avoid side effects and ensure proper use, talk to your healthcare professional before you take CEREBYX. Talk about any health conditions or problems you may have, including if you:

• have ever had a rash or unusual reaction while taking fosphenytoin sodium or any other antiepileptic medicines.
• have kidney problems, including any phosphate restrictions.
• have liver problems.

• drink alcohol. Drinking alcohol with CEREBYX may make you less alert and may make feelings of anger, confusion, or sadness worse.

• have absence seizures, also called petit mal (brief episodes of zoning out or staring without physical convulsions).
• are pregnant or planning to become pregnant. CEREBYX can only be taken during pregnancy if your healthcare professional tells you to.
• are breast-feeding or planning to breast-feed. It is not known if CEREBYX is excreted in human milk.
• are taking hormonal birth control.
• have low blood pressure.
• have heart problems.
• are diabetic.

• are at a higher risk for developing serious skin reactions. This includes if you:

  • have a family history of skin reactions,
  • have had a serious skin reaction,
  • have a weaken immune system, or
  • are of African descent.
• are of Asian descent.
• have a blood disorder (e.g., porphyria).
• have had an allergic reaction or have a family history of allergic reactions to medicines similar to CEREBYX such as carboxamides (e.g., carbamazepine), barbiturates, succinimides, and oxazolidinediones (e.g., trimethadione).
• are being or planning to be treated with radiation therapy to the brain and corticosteroids (a medicine used to reduce inflammation).
• have low bone density. Your healthcare professional may give you vitamin D with your treatment.
• have had genetic testing done and been told that you are positive for the HLA-B*1502 allele.
• are critically ill or elderly.

Other warnings you should know about:

Pregnancy:

• Tell your healthcare professional before taking CEREBYX if you are pregnant or are planning to become pregnant. There are specific risks to you and your unborn child that you should discuss with your healthcare professional. This can include increasing the frequency of your seizures and negative effects to your unborn child.

• If you become pregnant while taking CEREBYX, tell your healthcare professional right away. They will talk to you about registering with the North American Antiepileptic Drug (NAAED) Pregnancy Registry. The purpose of this registry is to collect information about the safety of

  • -888-233-2334. Information on the registry can also be found at the website http://www.aedpregnancyregistry.org/.

Check-ups and testing: Your healthcare professional will assess your health before and throughout your treatment. This will depend on your health condition and may include:

• testing your blood profile (CEREBYX may cause abnormal blood test results);
• checking your blood pressure;
• monitoring your heart rate and rhythm;
• monitoring your breathing and lungs;
• monitoring your mental health;
• genetic screening.

Tell your healthcare professional about all the medicines you take, including any drugs, vitamins, minerals, natural supplements or alternative medicines.

The following may interact with CEREBYX:

• alcohol.
• analgesic and anti-inflammatory agents, used to relieve pain and reduce inflammation (e.g., corticosteroids, phenylbutazone, and salicylates).
• anesthetics, used to produce a local or general loss of sensation including pain (e.g., halothane).
• antiarrhythmic drugs, used to treat irregular heart rates and/or rhythm problems (e.g., amiodarone, mexiletine, and quinidine).
• antibacterial agents, used to treat bacterial infections (e.g., chloramphenicol, ciprofloxacin, doxycycline, erythromycin, isoniazid, praziquantel, rifampin, sulfisoxazole, sulfonamides, and tetracycline).
• anticancer drugs, used to treat cancer (e.g., bleomycin, capecitabine, carboplatin, cisplatin, doxorubicin, fluorouracil, methotrexate, and teniposide).
• antidepressants, used to treat depression (e.g., trazodone, tricyclic antidepressants, and selective serotonin reuptake inhibitors such as fluoxetine, fluvoxamine, paroxetine, and sertraline).
• antifungal agents, used to treat fungal infections (e.g., amphotericin B, fluconazole, itraconazole, ketoconazole, miconazole, posaconazole, and voriconazole).
• antiretroviral, used to treat HIV (e.g., delavirdine, efavirenz, fosamprenavir, indinavir, lopinavir/ritonavir, nelfinavir, ritonavir, and saquinavir).
• antiulcer agents, used to prevent or treat ulcers (e.g., sucralfate).
• bronchodilators, used to treat narrowed or inflamed airways (e.g., theophylline).
• cyclosporine, used to prevent organ rejection after transplants.
• digoxin and digitoxin, used to treat heart failure.
• disulfiram, used to help with alcohol use disorders.
• diuretics (also known as “water pills”), used to increase urine production and lower blood pressure.
• folic acid, used to prevent and treat low folate.
• hormones, used for birth control, hormone replacement therapy, and to regulate menstrual cycles (e.g., estrogens and oral contraceptives).
• medicines used to lower blood pressure (e.g., reserpine and calcium channel blockers such as diltiazem, nicardipine, nifedipine, nimodipine, nisoldipine, and verapamil).
• medicines used to reduce stomach acid production (e.g., proton pump inhibitors such as omeprazole, and H₂-antagonists such as cimetidine).
• medicines used to thin the blood and prevent blood clots (e.g., coumarin, ticlopidine, and warfarin).
• neuromuscular blocking agents, used to relax muscles during surgery (e.g., pancuronium and vecuronium).
• opioid analgesics, used to relieve moderate to severe pain (e.g., methadone).
• oral hypoglycemic agents, used to lower blood sugar levels (e.g., chlorpropamide, diazoxide, glyburide, and tolbutamide).
• other anti-epileptic drugs, used to prevent epilepsy or seizures (e.g., barbiturates, carbamazepine, ethosuximide, felbamate, lamotrigine, methsuximide, oxazolidinediones, oxcarbazepine, phenobarbital, sodium valproate, succinimides, topiramate, valproic acid, and vigabatrin).
• psychotropic agents, used to treat mental health disorders or change your mental state or mood (e.g., benzodiazepines, chlordiazepoxide, clozapine, diazepam, methylphenidate, and phenothiazines).
• St. John’s Wort, a herbal medicine used to treat depression.
• statins, used to lower cholesterol levels (e.g., atorvastatin, fluvastatin, and simvastatin).
• vitamin D, used for calcium absorption and bone health.

How to take CEREBYX:

• CEREBYX will be prepared and given to you by your healthcare professional.
• CEREBYX will be slowly injected into your veins (intravenously or IV). It will not be injected using any other route due to the potential of serious side effects.
• Do NOT stop taking CEREBYX without talking to your healthcare professional. Suddenly stopping your treatment can cause serious side effects, including increased seizure frequency. Your healthcare professional will monitor and guide you on how to safely stop taking CEREBYX.

Usual dose:

Your healthcare professional will decide the right dose of CEREBYX for you. This can depend on your medical condition, age, current health, if you take other medication, and how you react to CEREBYX.

Overdose:

What are possible side effects from using CEREBYX?

These are not all the possible side effects you may have when taking CEREBYX. If you experience any side effects not listed here, tell your healthcare professional.

Side effects of CEREBYX include:

• changes in taste,
• constipation,
• drowsiness
• dry mouth,
• eyes moving involuntarily,
• ringing in the ears,
• sensation of tingling, tickling, or burning of the skin,
• shakiness.

Serious side effects and what to do about them

Serious side effects and what to do about them

If you have a troublesome symptom or side effect that is not listed here or becomes bad enough to interfere with your daily activities, tell your healthcare professional.

Reporting Side Effects

Storage:

Your healthcare professional will be stored in a refrigerator at 2° to 8°C. The product should not be stored at room temperature for more than 48 hours. Keep out of reach and sight of children.

If you want more information about CEREBYX:

• Talk to your healthcare professional.
• Find the full Product Monograph that is prepared for healthcare professionals and includes the Patient Medication Information by visiting the Health Canada website: (https://www.canada.ca/en/health-canada/services/drugs-health-products/drug-products/drug-product-database.html); ( the manufacturer’s website (www.searchlightpharma.com), or by calling 1-855-331-0830.

Last Revised: DEC 20, 2024