Phenytoin Sodium Injection USP (Sandoz Canada): Uses, Side Effects and Dosage

Serious warnings and precautions box

Cardiovascular risk: You will receive PHENYTOIN SODIUM INJECTION USP through an injection into the vein or muscle. If your healthcare professional injects this medication into the vein too fast, your blood pressure may drop quickly, and you may experience an irregular heartbeat. This can be serious. Your healthcare professional should monitor you closely while you are receiving PHENYTOIN SODIUM INJECTION USP and after.

What PHENYTOIN SODIUM INJECTION USP is used for:

PHENYTOIN SODIUM INJECTION USP is used to:

• control certain types of seizures (generalized tonic-clonic status epilepticus)
• prevent and treat seizures during surgery of the nervous system (e.g., brain, nerves, spinal cord)

How PHENYTOIN SODIUM INJECTION USP works:

PHENYTOIN SODIUM INJECTION USP belongs to a group of medicines called anticonvulsants. It works by blocking electrical impulses in the brain that cause seizures.

The ingredients in PHENYTOIN SODIUM INJECTION USP are:

Medicinal ingredient: phenytoin sodium

Non-medicinal ingredients: ethyl alcohol, propylene glycol, sodium hydroxide, and water for injection.

PHENYTOIN SODIUM INJECTION USP comes in the following dosage form:

Solution for injection; 50 mg / mL

Do not receive PHENYTOIN SODIUM INJECTION USP if:

• you are allergic to phenytoin sodium or to any of the other ingredients in PHENYTOIN SODIUM INJECTION USP or its container.
• you are allergic to other medicines of the hydantoin family, including fosphenytoin.
• you have a heart rhythm condition such as a slow heart rate (bradycardia), heart block, or certain other heart conditions (e.g., Adams-Stokes syndrome).
• you take delavirdine, used to treat HIV infection.

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

• have a personal or family history of rash or unusual reaction while taking phenytoin sodium or any other anti-seizure medicines.

• are currently taking any other medications, supplements or other special treatments:

  • as they may interact with PHENYTOIN SODIUM INJECTION USP, and this can affect how well they or PHENYTOIN SODIUM INJECTION USP work.
  • including prescription or non- prescription medications, dietary supplements (e.g., vitamins), herbal supplements, nutritional drinks, and tube feeding preparations.
  • PHENYTOIN SODIUM INJECTION USP may decrease the effectiveness of medications containing estrogen (e.g., hormonal birth control methods or hormone replacement therapies).
• have kidney or liver problems.
• drink alcohol occasionally or on a regular basis.
• have suicidal thoughts or behaviours.
• are pregnant, think you might be pregnant, or planning to become pregnant.
• are breastfeeding or planning to breastfeed.
• have high blood sugar levels or diabetes. PHENYTOIN SODIUM INJECTION USP may raise your blood sugar (glucose) levels.
• have porphyria (a condition that affects the nervous system and skin). PHENYTOIN SODIUM INJECTION USP can worsen your condition.
• have been told by a healthcare professional that you have low levels of albumin in your blood.
• are of Asian descent. You may be at higher risk of developing serious skin reactions during your treatment with PHENYTOIN SODIUM INJECTION USP.
• have absence seizures (brief, sudden lapse of consciousness) or seizures caused by low blood sugar levels or other conditions associated with your metabolism.
• have heart problems (e.g., heart failure).
• have breathing problems.
• have low blood pressure.
• are 65 years of age or older.
• are severely ill.

Other warnings you should know about:

Stopping your treatment: Do NOT stop taking PHENYTOIN SODIUM INJECTION USP without first talking to your healthcare professional. Suddenly stopping your treatment can cause you to have more seizures. Your healthcare professional will monitor and guide you on how to safely stop taking PHENYTOIN SODIUM INJECTION USP.

Serious side effects with PHENYTOIN SODIUM INJECTION USP can include:

• Bone problems: Talk to your healthcare professional if you have taken anti-seizure medications (such as phenobarbital, phenytoin, primidone, oxcarbazepine, lamotrigine, sodium valproate and/or carbamazepine) for a prolonged period. Long-term use of anti-seizure medications,

  • including PHENYTOIN SODIUM INJECTION USP, can lead to weakened or brittle bones. This can even lead to bone fractures.
• Gingival hyperplasia (overgrowth of gum tissue around the teeth): Talk to your healthcare professional about the best way to care for your teeth, gums, and mouth during your treatment with PHENYTOIN SODIUM INJECTION USP. It is very important that you care for your mouth properly to decrease the risk of gum damage.
• Suicidal thoughts and behaviour changes: If you have thoughts of harming or killing yourself at any time, contact a healthcare professional or go to a hospital right away. You may find it helpful to tell a relative or close friend how you are feeling and ask them to tell you if they notice any changes in your behaviour.
• Injection site reactions: PHENYTOIN SODIUM INJECTION USP may cause irritation and inflammation at the site of injection. It can also be accompanied by leakage into the surrounding tissue. A rare but serious complication called purple glove syndrome can also occur several days after your injection. Tell your healthcare professional right away if you experience pain, swelling, and purple-blue discolouration at the extremity of the limb where the injection was given. This can lead to tissue death, which may require surgical intervention.

• Serious skin reactions: Serious allergic reactions can be caused by anti-seizure medicines, often involving a skin reaction. These may occur within a month of starting treatment, but can occur later. Get help right away if you develop a skin rash, regardless of its severity, either alone or with a combination of the following symptoms:

  • any other serious skin reaction such as blistering or peeling of the mouth, nose, eyes or genitals,
  • fever,
  • swollen glands,
  • flu-like feeling,
  • swelling of the face and/or legs,
  • problems related to the liver, kidneys, heart, lungs or other organs.

See the Serious side effects and what to do about them table for more information on these and other serious side effects.

Alcohol: Do not drink alcohol during your treatment with PHENYTOIN SODIUM INJECTION USP without talking to your healthcare professional first. Drinking alcohol during your treatment may change your blood levels of phenytoin sodium, which can cause serious side effects.

Driving and using machines: Patients with uncontrolled epilepsy should not drive or operate machinery. PHENYTOIN SODIUM INJECTION USP may cause you to feel dizzy or drowsy. Avoid doing tasks which require special attention until you know how PHENYTOIN SODIUM INJECTION USP affects you.

Testing and check-ups:

• Your healthcare professional may ask you to do a genetic test before you receive PHENYTOIN SODIUM INJECTION USP. This test will determine if you have a high risk of experiencing serious skin reactions if you are given PHENYTOIN SODIUM INJECTION USP.

• You will have regular visits with your healthcare professional during your treatment with PHENYTOIN SODIUM INJECTION USP to monitor your health. They may:

  • do blood tests to monitor the amount of phenytoin sodium in the body.
  • talk to you about how you are feeling, and if you have suicidal thoughts and behaviours.
• PHENYTOIN SODIUM INJECTION USP can cause abnormal blood test results. Your healthcare professional will decide when to perform blood tests and will interpret the results.

Pregnancy, birth control and breastfeeding:

• Avoid becoming pregnant during your treatment with PHENYTOIN SODIUM INJECTION USP. If you become pregnant, your seizures may become worse. Your healthcare professional may need to adjust your dose.
• PHENYTOIN SODIUM INJECTION USP is not recommended during pregnancy as it can harm an unborn child. Tell your healthcare professional right away if you become pregnant or think you are pregnant during your treatment with PHENYTOIN SODIUM INJECTION USP. Your healthcare professional will discuss the potential risks to your unborn child with you. You and your healthcare professional will then decide if you should continue your treatment with PHENYTOIN SODIUM INJECTION USP or use other treatments while you are pregnant.
• If you are able to get pregnant, you should use an effective birth control method (contraception) during your treatment with PHENYTOIN SODIUM INJECTION USP. If you are using a hormonal birth control method, it might not work. Talk to your healthcare professional about the best non-hormonal birth control methods to use during your treatment with PHENYTOIN SODIUM INJECTION USP.
• Pregnancy Registry: If you become pregnant during your treatment with PHENYTOIN SODIUM INJECTION USP, talk to your healthcare professional about registering with the North American Antiepileptic Drug Pregnancy Registry. You can enroll in this registry by calling 1-888-233-2334. The purpose of this registry is to collect information about the safety of antiepileptic medicines during pregnancy. Information about the registry can also be found at the website: http://www.aedpregnancyregistry.org/.
• PHENYTOIN SODIUM INJECTION USP passes into breast milk and may harm your baby. Do not breastfeed during treatment with PHENYTOIN SODIUM INJECTION USP. Talk to your healthcare professional about the best way to feed your baby during this time.

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 PHENYTOIN SODIUM INJECTION USP:

• Alcohol
• Other medicines used to treat seizures or epilepsy (e.g., ethosuximide, oxcarbazepine, carbamazepine, topiramate, phenobarbital, sodium valproate, valproic acid, quetiapine, lamotrigine, vigabatrin, diazepam)
• Medicines used to treat heart rhythm problems (e.g., amiodarone, mexiletine, verapamil)
• Medicines used to treat cancer (e.g., capecitabine, fluorouracil, bleomycin, carboplatin, cisplatin, doxorubicin, methotrexate, irinotecan, paclitaxel)
• Medicines used to treat bacterial infections (e.g., sulfamethoxazole-trimethoprim, doxycycline)
• Medicines used to treat fungal infections (e.g., fluconazole, ketoconazole, itraconazole, voriconazole, posaconazole)
• Medicines used to treat anxiety and alcoholism (e.g., chlordiazepoxide, diazepam)
• Medicines used to reduce the amount of acid in the stomach (e.g., cimetidine, omeprazole)
• Estrogen containing medications (including birth control methods or hormone replacement therapies)
• Medicines used to treat depression (e.g., fluoxetine, paroxetine, fluvoxamine, sertraline, trazodone)
• Medicines used to treat high blood cholesterol (e.g., fluvastatin, atorvastatin, simvastatin)
• Medicines used to treat tuberculosis (e.g., isoniazid, rifampin)
• Medicines known as phenothiazines, used to treat schizophrenia and other psychotic disorders
• Medicines used for muscle relaxation during surgery (e.g., rocuronium, cisatracurium)
• Medicines used to prevent blood clots (e.g., ticlopidine, warfarin)
• Medicines used to treat HIV infection (e.g., delavirdine, ritonavir, efavirenz, lopinavir)
• Medicines used to treat high blood pressure (e.g., nifedipine, beta blockers)
• Medicines used to treat inflammation (e.g., corticosteroids, acetylsalicylic acid (ASA), magnesium salicylate)
• Halothane, used for general anesthesia
• Methylphenidate, used to treat ADHD
• Tolbutamide, used to treat high blood sugar levels
• Diazoxide, used to treat low blood sugar levels
• Furosemide, used to treat fluid retention
• Praziquantel, used to treat parasitic infections
• Cyclosporine, used to prevent the rejection of organ transplants
• Digoxin, used to treat various heart conditions
• Theophylline, used to treat asthma or other breathing problems
• Dopamine, used to treat severe heart failure and shock.
• Lidocaine, used to prevent pain caused by certain conditions or procedures
• St. John’s Wort, a herbal remedy
• Vitamin B9 (folic acid)
• Vitamin D (calciferol)
• Calcium
• Tube feeding preparations and related nutritional drinks or supplements

How PHENYTOIN SODIUM INJECTION USP is given:

• PHENYTOIN SODIUM INJECTION USP will be given to you:

  • by a healthcare professional, and
  • as an injection into a vein or muscle.
• Your healthcare professional may ask you to take supplements during your treatment to prevent side effects. Follow their instructions carefully.

Usual dose:

Your healthcare professional will decide the dose that is right for you.

Overdose:

Signs of an overdose with PHENYTOIN SODIUM INJECTION USP include:

• blurred vision, involuntary eye movements (side-to-side, up and down, circular motion)
• lack of muscle control or coordination, shaking (tremors), overactive reflexes
• low blood pressure
• lack of energy
• slurred or slow speech
• nausea or vomiting
• slow and ineffective breathing
• coma

If you think you, or a person you are caring for, have been given too much PHENYTOIN SODIUM INJECTION USP, contact a healthcare professional, hospital emergency department, regional poison control centre or Health Canada’s toll-free number, 1-844 POISON-X (1-844-764-7669) immediately, even if there are no signs or symptoms.

Missed dose:

PHENYTOIN SODIUM INJECTION USP is given by healthcare professionals. They will ensure that you receive your doses on time. If you feel that a dose has been missed, tell your healthcare professional.

Possible side effects from using PHENYTOIN SODIUM INJECTION USP:

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

Side effects with PHENYTOIN SODIUM INJECTION USP may include:

• Sleepiness/drowsiness, feeling tired/fatigue
• Headache, dizziness along with the feeling of a spinning movement
• Nausea/vomiting
• Changes in taste (metallic taste)
• Double vision, blurred vision
• Poor coordination (dizzy)
• Shakiness
• Unwanted, male-pattern hair growth in women
• Thickening of the gums

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

You can report any suspected side effects associated with the use of health products to Health Canada by:

• Visiting the Web page on Adverse Reaction Reporting (canada.ca/drug-device-reporting) for information on how to report online, by mail or by fax; or
• Calling toll free at 1-866-234-2345.

NOTE: Contact your healthcare professional if you need information about how to manage your side effects. The Canada Vigilance Program does not provide medical advice.

Storage:

• Your healthcare professional will store PHENYTOIN SODIUM INJECTION USP between 15^oC and 30^oC, protected from light. Freezing should be avoided.
• Keep out of reach and sight of children.

If you want more information about PHENYTOIN SODIUM INJECTION USP:

• 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 Drug Product Database website (https://www.canada.ca/en/health-canada/services/drugs-health-products/medeffect-

  • canada/adverse-reaction-reporting.html); the manufacturer’s website (www.sandoz.com); or by calling 1-800-361-3062.

Date of Authorization: 2026-01-19