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Generic Name: Phenytoin (oral) It is phenytoin (oral). FEN-i-toyn [FEN-i-toyn
Trade Names Include Dilantin and Phenytek.
Classes of Drugs: Group I antiarrhythmics; Hydantoin anticonvulsants

What is Phenytoin?

Phenytoin is an antiepileptic medicine, often known as an anticonvulsant. Phenytoin is a drug that slows down the brain's impulses, which trigger seizures.

Phenytoin is used to manage seizures. It is not a cure for all types of seizures, and your physician will decide whether it is the best medication for you.


Phenytoin is not a good choice when you are also taking delavirdine (Rescriptor) or if you're allergic to ethotoin (Peganone) or fosphenytoin (Cerebyx) as well as mephenytoin (Mesantoin). If you're pregnant and you are taking this medication, unless your physician advises you to, Phenytoin can harm the unborn baby. However, experiencing a seizure during pregnancy could be harmful to both the mother and baby. If you are pregnant while using this medication, do not stop taking the medicine unless you have the advice of your physician. Controlling seizures is crucial during pregnancy, and the advantages of preventing seizures can surpass any risk posed by taking phenytoin.

If you notice any new or deteriorating symptoms, report them to your physician for treatment, including changes in behavior or mood, changes in mood or anxiety, or when you feel anxious and restless, angry, or excessively hyperactive (mentally as well as physically), or are having thoughts about suicide or harming yourself.

Before you Take this Drug

Phenytoin should not be used if you are allergic to it or if you've previously had:

  • Problems with the liver due to phenytoin
  • Allergies to the same medications like ethotoin, fosphenytoin, mephenytoin, fosphenytoin,
  • If you're currently taking delavirdine (Rescriptor).

To ensure that phenytoin is suitable for you, ask your doctor if you have ever experienced:

  • Heart issues;
  • Liver disease;
  • Diabetes;
  • Depression;
  • Suicidal ideas or actions;
  • A vitamin D deficiency or other medical reason that causes thinning bones;
  • Porphyria (a genetic disorder of enzymes that can cause symptoms in the nervous system, skin,
  • If you have Asian descent, you might require a specific blood test to determine the risk of developing a skin reaction from this medication.

There are people who have thoughts of suicide while taking this medication. Your doctor should monitor your progress on a regular basis during checkups. Your family members and other caregivers should be aware of changes in your symptoms or mood.

Controlling your seizures is vital during pregnancy. Don't begin and stop taking phenytoin unless you have your doctor's guidance in case you are expecting. Phenytoin may harm the unborn baby; however, experiencing a seizure in pregnancy can harm both the baby and mother. Talk to your doctor when you begin to become pregnant while using this medication.If you're expecting, then your name might be added to an OB-GYN registry to track any effects of the phenytoin on the baby.

If you've taken this medication during pregnancy, you should inform the doctor who delivered your baby about the use of phenytoin. Both of you might require medication to avoid bleeding too much at the time of delivery and shortly after birth.

Phenytoin may make contraceptives less efficient. Consult your physician about an alternative to hormonal birth control (condom diaphragm or diaphragm that contains spermicide) to avoid pregnancy.It is not recommended to breastfeed while taking this medication. Consult your physician regarding any risks.

How to Take Phenytoin?

Use phenytoin as directed by your physician. Follow the directions on the prescription label and study the entire medication guide or instruction sheet. Your doctor may modify your dose.Take a swallow of the extended-release capsule in its entirety, but do not crush or chew on it, break it, or even open it.

Phenytoin chewable tablets aren't meant to be used for a daily dose. It is recommended to take them 2–3 times a day. Follow the instructions of your physician for dosage extremely carefully.shake up the oral suspension (liquid) prior to determining the dose. Utilize the dosing syringe that comes with it or a dosage-measuring device (not the kitchen spoon).

It is possible that you require regular blood tests. It is also possible to require a blood test if you change forms. Visit your doctor regularly.

Talk to your doctor if you feel that phenytoin doesn't seem to be effective in reducing your seizures. Don't stop taking the medication suddenly, even if you are well. The abrupt stop can cause seizures. Follow the advice of your doctor about the process of tapering your dose.In the event of an emergency Wear or carry a medical ID to let the world know that you suffer from seizures.

Phenytoin causes swelling in your gums. Make sure you floss and brush your teeth, as well as visit your dentist frequently, to avoid this issue.Keep at room temperature, away from light, moisture, and heat.

Details on Dosage

Usual Adult Dose for Seizures:

orally (except suspension) Dosage for loading Only when prescribed for patients.
1 g of oral suppositories divided into 3 doses (400 mg, 300 mg, and 300 mg) administered at two-hour intervals The normal maintenance dose then began 24 hours after the loading dose.
Initial dosage: 100 mg of extended-release taken orally three times per day.
Maintenance dosage: 100 mg taken orally three to four times per day. If seizure control has been achieved with a divided dose of three capsules containing 100 mg every day, a daily dose of 300 mg of extended-release sodium phenytoin could be thought of as In addition, the dose may have to be increased to 200 mg taken orally three times a day, should it be required.
Suspension: Patients who've not received any previous treatment may start with one hundred and 125 mg (one teaspoonful) of suspension three times per day. The dose can be adjusted according to your individual needs. A further increase of five teaspoonfuls per day may be made if required.
IV Don't overdose at 50 mg/min.
Dosage of loading 10–15 mg/kg intravenous gradually
Dosage for maintenance: 100 mg intravenously every 6–8 hours.
IM Avoid the IM route due to irregular absorption.

Usual Adult Dose for Arrhythmias:

Loading Dose:
1.25 mg/kg IV every five minutes. Can repeat this until 15 mg/kg or
250 mg orally, 4 times per day for 1 day, and then 250 mg every day for 2 days.
Maintenance Dose:
300–400 mg/day orally, in doses divided between 1 and 4 times per day.

Usual Adult Dose for Status Epilepticus:

Dosage for loading: The manufacturer suggests 10-15 mg/kg via slowly administered IV (at a rate of not more than 50 mg/minute). In addition, generally accepted guidelines recommend 15-20 mg/kg via slowly administered IV therapy (at an amount not exceeding 50 mg/min).
Maintaining dosage: 100 mg per day in IV every 6–8 hours
Maximum rate: 50 mg/minute

Dosage for maintenance Orally or IV, 100 mg every 6–8 hours

Usual Adult Dose for Neurosurgery:

Neurosurgery (prophylactic): 100 to 200 mg IV in approximately 4-hour intervals during the surgery and for the postoperative period. Note that while the manufacturer suggests IM treatment, the procedure can cause extensive necrosis and tissue destruction locally. (Some doctors recommend the use of fosphenytoin when IM administration is needed.) When IM treatment isn't needed, the most commonly used protocol is 100–200 mg IV in approximately four hours during the surgery and immediately following surgery.

Usual Pediatric Dose for Seizures:

Status Epilepticus: Loading Dose:
Children, Infants Between 15 and 20 mg/kg intravenous in a single or divided dose
Anticonvulsant: Loading Dose:
All age groups: 15 to 20 mg/kg taken orally (based on phenytoin serum levels and dosing patterns in the past). The oral loading dose must be divided into 3 doses, administered every 2 to 4 hours.
Anticonvulsant: Maintenance Dose:
(IV as well as oral) (Note to note: You may initially divide the daily dose into three doses a day, then alter to meet personal needs.)
Not more than or equal to 4 weeks In the beginning: 5 mg/kg/day, in two doses divided
Usual dose: 5-8 mg/kg/day IV, divided into two doses (may require doses for each 8-hour period).
More than or equal to In the beginning, 5 mg/kg/day was divided into 2 or 3 doses.
Normal: (may require up to 8 hours of dosing)
From 6 months to 3 years 6 months to 3 years: 8 to 10 mg/kg/day
From 4 to 6 years old: 7.5 to 9 mg/kg/day
Between 7 and 9 years old 7 to 9 years old: 7-8 mg/kg/day
Ages 10–16: 6–7 mg/kg/day

Usual Pediatric Dose for Arrhythmias:

Over 1 year:
Loading dose of 1.25 mg/kg IV every five minutes. It is possible to repeat this until you reach 15 mg/kg.
Maintenance Dose: 5–10 mg/kg/day by IV or orally within 2–3 split doses

What Happens If I Miss a Dose?

You should take the medication as quickly as you are able, but avoid any missed doses if you are close to the time of the next dose. Don't take two doses at a time.

What Happens If I Overdose?

Get medical attention immediately, contact the hospital immediately for medical attention, or call the Poison Help line at 1-800-222-1222. Phenytoin is a poison that, if overdosed, could be fatal. Overdose symptoms may include eye movements that twitch or slurred speech. losing balance and tremors; muscle stiffness or weakness; vomiting; and fainting. You may also feel lightheaded, faint, and have slow or shallow breathing.

What Should be Avoided?

Do not drink alcohol when you take phenytoin. Drinking alcohol can raise the levels of phenytoin in your blood and increase the risk of side effects. Alcohol consumption on a regular basis can lower the phenytoin levels in your blood, which may increase the risk of having seizures.

Talk to a pharmacist or doctor prior to taking over-the-counter medicines like omeprazole, cimetidine, St. John's wort, minerals, and vitamins that contain folic acid.Avoid driving or engaging in hazardous activities until you understand the effects of this medication on your body. Your reaction could be affected.

Beware of taking antacids when you are taking phenytoin. Antacids can make it difficult for the drug to be absorbed by your body.

Side effects of Phenytoin

See a doctor immediately when you notice symptoms warning of an allergy reaction to the phenytoin (hives or breathing problems and swelling of your throat or face) or a severe reaction to your skin (fever and sore throat, burning eyes or skin, pain, the skin is red or purple that gets worse and leads to blisters as well as peeling).

Get medical attention in the event of a serious drug reaction that could affect the body in a variety of ways. Symptoms may include an itch on your skin or fever, swelling of the glands, muscle aches, extreme weakness, unusual bruising, or yellowing of the eyes or skin.

Inform your doctor about any symptoms that are getting worse or are new to you, like changes in behavior or mood, anxiety, panic attacks, trouble sleeping, or if you are feeling uncontrollably angry, irritable, or aggressive. Hyperactive, anxious (mentally as well as physically) and depressed and contemplating suicide, or self-harming

Contact your doctor immediately. If you are suffering from:

  • Unsteady or irregular rhythms of the heart, chest flutters, and dizziness (like it's possible to faint);
  • Any skin rash, regardless of how minor;
  • Fever and chills, as well as a sore throat and swollen glands;
  • Gums with swelling or redness, mouth sores, red gums
  • Bleeding, bruising that is easy to stop in red or purple spots under your skin,
  • Liver issues, loss of appetite, abdomen pains, dark urine stool colored by clay, jaundice (yellowing of the eyes or skin).

The most common side effects of phenytoin are:

  • Drowsiness, confusion;
  • Speech that is slurred;
  • Unusual eye movements abnormal eye movement
  • Issues in coordination, balance, or muscle movements.

This is not a comprehensive list of all the side effects. Other effects may also be present. Consult your physician to seek medical advice on the effects. You may report any adverse reactions to the FDA at 1-800-FDA-1088.

Interaction with Other Drugs

It is sometimes not recommended to take certain medications together. Certain medications can alter the blood levels of other medications that you take, which can cause more side effects or make the drugs less effective.

Numerous drugs interact with the hormone phenytoin. There are many possible interactions that are not described in this article. Speak to your doctor about all other medications you take as well as any medications you begin or stop taking during treatment. This includes over-the-counter and prescription supplements, vitamins, and herbs.



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