Phenytoin is a drug to prevent and relieve seizures in people with epilepsy. This drug can also sometimes be used to treat trigeminal neuralgia, which is pain in the face due to a disorder of the fifth nerve.Phenytoin or phenytoin is available in capsule and injectable forms.
Seizures occur due to interference with electrical signals in the brain, so that the muscles of the body tense up (contract) and cause uncontrollable movements. Phenytoin works by reducing excess electrical activity in the brain, so seizures can subside.
Phenytoin trademarks: Curelepz, Decatona, Dilantin, Ikaphen, Kutoin, Phenitin, Phenytoin Sodium
What is Phenytoin
| Category | Anticonvulsants |
| group | Prescription drugs |
| Benefit | Overcoming seizures |
| Used by | Adults and children |
| Phenytoin for pregnant and lactating women | Category D: There is positive evidence of risks to the human fetus, but the benefits may outweigh the risks, for example in dealing with life-threatening situations. Phenytoin can be absorbed into breast milk. Consult your doctor first if you want to use phenytoin while breastfeeding. |
| Drug form | Capsules and injections |
Precautions Before Using Phenytoin
Phenytoin should not be used carelessly. Before using phenytoin, you need to pay attention to the following points:
- Tell your doctor if you are allergic to certain medicines, including anticonvulsants. Do not use phenytoin if you are allergic to this drug.
- Tell your doctor if you have or have ever had arrhythmia, liver disease, heart disease, low thyroid hormone, agranulocytosis, anemia, thrombocytopenia, pancytopenia, diabetes, or porphyria.
- Do not drive a motor vehicle or operate equipment that requires alertness, after using phenytoin, as this medicine may cause dizziness or drowsiness.
- Do not consume alcoholic beverages while on treatment with phenytoin, as alcohol can affect blood levels of this drug.
- Tell your doctor if you are taking certain medications, supplements, or herbal products.
- Tell your doctor if you are pregnant, breastfeeding, or planning a pregnancy.
- Perform regular check-ups as recommended by the doctor and do not stop using phenytoin suddenly because it has the potential to worsen the condition.
- See your doctor right away if you have an allergic drug reaction, a more serious side effect, or an overdose, after using phenytoin.
Dosage and Instructions for Use of Phenytoin
The dose of phenytoin given by the doctor may vary, depending on the age and condition of the patient. Below is a breakdown of common phenytoin dosages:
Condition: Epilepsy
- Mature: The initial dose is 3–4 mg/kg or 150–300 mg per day. The maintenance dose is 200–500 mg per day.
- Children: The initial dose is 5 mg/kgBW per day, can be divided into 2 consumption schedules. The maintenance dose is 4-8 mg/kgBW per day, can be divided into several consumption schedules. The maximum dose is 300 mg per day
Condition: Status epilepticus or persistent seizures
- Mature: 10–15 mg/kgBW given by slow intravenous injection (intravenous/IV). The maintenance dose is 100 mg 3-4 times a day.
- Children: 15-20 mg/kgBW given by IV infusion at a slow rate.
How to Use Phenytoin Correctly
Follow the doctor's advice and always read the instructions for use listed on the phenytoin package before using it. Do not increase or decrease your dose and stop taking phenytoin without consulting your doctor first.
Injectable phenytoin must be administered by a doctor or medical officer under the supervision of a doctor.
Phenytoin capsules can be taken with meals. This is done to prevent stomach pain. Phenytoin capsules can be taken with the help of a glass of water.
Try to take the drug at the same time every day, in order to get the maximum benefit. For patients who forget to take phenytoin, it is advisable to do so as soon as they remember if the distance to the next consumption schedule is not too close. If it is close, ignore it and do not double the dose.
Please note, the use of phenytoin for people with chronic epilepsy can reduce the mineral content in the bones. Phenytoin is also at risk of reducing vitamin D from the body, thus causing low levels of calcium and phosphate in the blood.
Store the medicine at room temperature. Do not store the medicine in a place exposed to direct sunlight, heat, or humidity. Keep medicine out of reach of children.
Phenytoin Interactions with Other Drugs
There are some drug interactions that can occur if phenytoin is used in combination with other medicines, such as:
- Increases blood levels of phenytoin when used with amiodarone, ketoconazole, capecitabine, chloramphenicol, fluorouracil, disulfiram, fluoxetine, fluvoxamine, cimetidine, isoniazid, omeprazole, sertraline, ticlopidine, valproic acid, or warfarin
- Lowering blood levels of phenytoin when used with bleomycin, carbamazepine, folic acid, phenobarbital, or sucralfate
- Lowering blood levels of albendazole, atorvastatin, ciclosporine, digoxin, efavirenz, quetiapine, apixaban, praziquantel, or simvastatin
- Decreases the effectiveness of azole antifungal drugs, estrogen, birth control pills, corticosteroids, doxycycline, furosemide, irinotecan, paclitaxel, theophylline, or vitamin D
Phenytoin Side Effects and Dangers
There are some side effects that can occur when using phenytoin. Side effects that can arise include:
- Headache, dizziness, or vertigo
- Nauseous
- Throw up
- Constipation
- Feeling sleepy
- Difficulty sleeping
- Feeling nervous
- Gums become swollen and bleed
Call your doctor if the side effects above don't get better and get worse. Call your doctor right away if you have an allergic reaction or serious side effects, such as:
- Easy bruising
- Slow heart rate
- Nystagmus
- Words become unclear
- Blurred vision
- Increased frequency of urination
- Easy to feel thirsty
- Impaired body coordination
- Jaundice
- Excessive hair growth
- Easy to break bones
- Suicidal ideation appears
In addition, in men, the use of phenytoin can cause side effects in the form of an erection that lasts longer and even causes pain. Immediately see a doctor if you experience these side effects.