Phenytoin Sodium: Uses, Side Effects and Dosage

What is PHENYTOIN SODIUM used for?

PHENYTOIN SODIUM is used to help:

• control certain types of seizures, called tonic-clonic (grand mal) seizures, and psychomotor (temporal lobe) seizures.
• prevent and treat seizures that may occur during or after surgery to the brain.

How does PHENYTOIN SODIUM work?

PHENYTOIN SODIUM belongs to a group of medicines called anti-seizure medicines. It works by slowing down electrical impulses in the brain that cause seizures.

What are the ingredients in PHENYTOIN SODIUM?

Medicinal ingredients: Phenytoin sodium.

Non-medicinal ingredients: colloidal silicon dioxide, hydroxypropyl methylcellulose, and magnesium stearate.

Capsule shells: D&C Red No. 28, D&C Yellow No. 10, FD&C Red No. 40, gelatin, and titanium dioxide.

Pharmaceutical ink: D&C Yellow No. 10 Aluminum Lake, FD&C Blue No. 1 Aluminum Lake, FD&C Blue No. 2 Aluminum Lake, FD&C Red No. 40 Aluminum Lake, iron oxide black, propylene glycol, and shellac.

PHENYTOIN SODIUM comes in the following dosage forms:

Capsules: 100 mg.

Do not use PHENYTOIN SODIUM if you/your child:

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

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

• are taking any other medications, supplements or other special treatments.

  • they may interact with PHENYTOIN SODIUM, and this can change how well they or PHENYTOIN SODIUM works.
  • they include prescription or non-prescription medications, dietary supplements (e.g., vitamins), herbal supplements, nutritional drinks, and enteral feeding preparations.
• have ever had an allergic rash while taking phenytoin or any other anti-seizure medicine.

• have a personal or family history of severe allergic reaction to phenytoin or any other anti-seizure medicines.

  • symptoms can include fever, rash, swollen lymph gland, and liver problems (seen as yellowing of skin and the whites of the eyes).
• drink alcohol occasionally or regularly.
• are 65 years of age or older.

• are female and:

  • are breastfeeding or plan to breastfeed.
  • are pregnant or plan to become pregnant.
  • are using hormonal birth control, such as the birth control pill.
• are of Asian and/or Black descent. You or your child may be at higher risk of developing serious skin reactions during treatment with PHENYTOIN SODIUM.

• have or have had any of the following diseases or conditions:

  • depression, mood problems, or suicidal thoughts or behaviours.
  • diabetes.
  • heart problems, including slow or fast heart rate, or past heart attack.
  • liver or kidney problems.
  • low levels of albumin or high levels of bilirubin in the blood.
  • porphyria (a condition that affects the nervous system and skin). PHENYTOIN SODIUM can worsen your condition.
  • immune system problems, such as immune suppression or compromise.
  • are having radiation therapy for the brain and take corticosteroids (medicines used to treat inflammation).
  • a medical condition (such as surgery) that prevents you from taking PHENYTOIN SODIUM orally.

Other warnings you should know about:

Do not stop your treatment with PHENYTOIN SODIUM without first checking with your healthcare professional. This could lead to a sudden worsening of your seizures.

Pregnancy, birth control and breastfeeding:

• Avoid becoming pregnant while you are on PHENYTOIN SODIUM. If you become pregnant while taking PHENYTOIN SODIUM, your seizures may become worse. Your healthcare professional may change your dose of PHENYTOIN SODIUM.
• If you take PHENYTOIN SODIUM during pregnancy, your baby is at risk for serious birth defects, and cognitive disabilities. Your baby is also at risk for bleeding problems right after birth.
• If you are pregnant or able to get pregnant, talk to your healthcare professional about using other treatments instead of PHENYTOIN SODIUM. If the decision is made to use PHENYTOIN SODIUM, you should use effective birth control (contraception) during your treatment. If you are using hormonal birth control, it might not work with PHENYTOIN SODIUM. Talk to your healthcare professional about the best kind of birth control to use while you are taking PHENYTOIN SODIUM.
• Tell your healthcare professional right away if you become pregnant or think you are pregnant during treatment with PHENYTOIN SODIUM. You and your healthcare professional should decide if you will continue to take PHENYTOIN SODIUM while you are pregnant.
• Pregnancy Registry: If you become pregnant while taking PHENYTOIN SODIUM, 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 passes into breast milk and may harm your baby. Do not breastfeed during treatment with PHENYTOIN SODIUM. Talk to your healthcare professional about the best way to feed your baby during this time.

Driving or using machines: PHENYTOIN SODIUM may make you feel dizzy, drowsy and affect your coordination. Avoid driving, using machinery, or doing activities that requires you to be alert until you know how PHENYTOIN SODIUM affects you.

Alcohol: Do not drink alcohol while taking PHENYTOIN SODIUM, without first talking to your healthcare professional. Drinking alcohol while taking PHENYTOIN SODIUM may change your blood levels of phenytoin, which can cause serious side effects.

Check-ups and testing:

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

• You will have regular visits with your healthcare professional while you are taking PHENYTOIN SODIUM to monitor your health. They will:

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

PHENYTOIN SODIUM can cause serious side effects, including:

• Suicidal thoughts and behaviour changes: This medicine may cause some people to be agitated, irritable, or display other unusual behaviours. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed. You may find it helpful to tell a relative or close friend you are taking PHENYTOIN SODIUM. Ask them to read this leaflet. You might ask them to tell you if they:

  • think your depression is getting worse, or
  • are worried about changes in your behaviour.

If you have thoughts of harming or killing yourself or others at any time, tell your healthcare professional or go to a hospital right away. Close observation by a healthcare professional is necessary in this situation.

• Serious skin reactions: Serious allergic reactions can be caused by anti-seizure medicines, often involving a skin reaction. These may occur shortly after starting treatment, or several months later. Get help right away if you/your child 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.
• Bone problems (including osteoporosis, osteopenia, osteomalacia): If you have taken anti-seizure medicines for a long time, it can lead to bone problems. This includes painful and weakened or brittle bones, and possibly 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. It is very important that you care for your mouth properly to decrease the risk of gum damage.

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

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

The following may interact with PHENYTOIN SODIUM:

• medicines used to treat or prevent:

  • seizures or epilepsy (other than PHENYTOIN SODIUM)
  • bacterial, fungal and parasitic infections
  • HIV infection
  • cancer
  • high blood pressure or certain heart conditions
  • high blood cholesterol
  • high blood sugar
  • blood clots (anticoagulants)
  • depression and other psychological conditions
  • anxiety or alcohol withdrawal
  • pain and inflammation
  • excess stomach acid or ulcers,
  • medicines used to suppress your immune system, and
  • medicines used as a muscle relaxant for intubation or surgery

• these medicines:

  • birth control pills and other birth control methods that use hormones
  • theophylline, used to treat asthma or other breathing problems
  • furosemide, used to lower extra fluid levels
  • halothane, used for general anesthesia
  • methadone, used to treat pain and opioid dependence
  • corticosteroids, used to treat inflammation
  • diazoxide, used to treat low blood sugar

• other supplements:

  • St. John’s Wort, a herbal remedy
  • vitamin D, vitamin B9 (folic acid)
  • tube feeding preparations and related nutritional drinks or supplements
• alcohol.

This is not a complete list.

How to take PHENYTOIN SODIUM:

• Always take PHENYTOIN SODIUM exactly as your healthcare professional has told you to. They will decide on the dose that is right for you/your child. Never increase or decrease your dosewithout talking to your healthcare professional.
• Do not stop taking PHENYTOIN SODIUM without talking to your healthcare professional. Stopping PHENYTOIN SODIUM suddenly can cause serious problems, including seizures that will not stop. Your healthcare professional will tell you if and when you/your child can stop taking this medicine.
• Do not take capsules that are discoloured.
• Tell your healthcare professional if you/your child have difficulty swallowing the capsules. They may prescribe you the oral suspension or chewable tablets instead.

Usual dose:

Adults:

• Usual initial dose: 300 mg total a day, divided into 3 doses (one 100 mg capsule, three times a day). Your PHENYTOIN SODIUM dose may be adjusted according to the effect it has, and to the level of medicine in your blood.
• Usual dose: 300 to 400 mg total a day, in divided doses. Your healthcare professional may adjust your dose if necessary. In some cases they may recommend that you take 300 mg once a day (3 capsules of 100 mg, taken together once a day). Follow your healthcare professional’s instructions carefully.

Children (below 18 years of age):

• Your child’s healthcare professional will determine the right dose based on your child’s weight. Follow their instructions carefully.
• PHENYTOIN SODIUM is intended for use in children over 6 years old, weighing at least 40 kg and who are able to swallow capsules.
• PHENYTOIN SODIUM is not available in any pediatric dosage forms i.e. a 30 mg capsule strength, a 50 mg chewable tablet, or an oral suspension of 30 mg in each 5 mL.

• Usual initial dose: A total of 5 mg/kg/day (5 mg per day for every kg they weigh), to be

  • divided and given in 2 or 3 doses. Your child’s PHENYOTIN SODIUM dose may be adjusted according to the effect it has, and to the level of medicine in their blood. The maximum dose is 300 mg (total) a day. Given that PHENYTOIN SODIUM is available only as a 100 mg capsule, the child must weigh at least 40 kg in order to initiate therapy with this product.
• Usual dose: 4 to 8 mg/kg/day, in divided doses. Children over 6 years old may require the minimum adult dose (300 mg/day).

Overdose:

Signs of an overdose with PHENYTOIN SODIUM 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, slow heart rate, poor blood circulation, heart suddenly stops beating (cardiac arrest),
• feeling sleepy or tired, lack of energy,
• slurred or slow speech,
• nausea or vomiting,
• slow and ineffective breathing,
• coma.

Missed Dose:

If you/your child miss a dose, take it as soon as you remember. However, if it is almost time for the next dose, skip the missed dose and take your next dose as scheduled . Do not take a double dose to make up for the missed dose.

What are possible side effects from using PHENYTOIN SODIUM?

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

Side effects may include:

• high blood sugar. If you have diabetes, closely monitor your blood sugar while taking PHENYTOIN SODIUM.
• spinning or dizziness (vertigo)
• trouble falling asleep, or feeling sleepy
• nausea or vomiting, constipation
• nervousness
• headache
• burning or prickling sensation on the skin (sometimes called “pins and needles”)
• changes in facial features
• additional body and facial hair
• change in tastes

Serious side effects and what to do about them

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:

• Store at controlled room temperature 15°C to 30°C. Protect from light and moisture.
• Keep out of reach and sight of children.

If you want more information about PHENYTOIN SODIUM:

• Talk to your healthcare professional
• Find the full product monograph that is prepared for healthcare professionals and includes this 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 (https://www.aapharma.ca/en/), or by calling 1-877-998-9097.

Last revised: DEC 10, 2022