Generic Name: mephenytoin (meh FEN i toyn)Brand Names: Mesantoin
Mephenytoin is a drug used to control seizures. It works by slowing down impulses in the brain that cause seizures.
Mephenytoin is usually reserved for seizure conditions that have not responded to other less toxic antiseizure medicines.
Mephenytoin is not commercially available in the United States.
Mephenytoin may also be used for purposes other than those listed in this medication guide.
Mephenytoin is not commercially available in the United States.Do not stop taking your medication even if you feel better. It is important to continue taking mephenytoin to prevent your seizures from recurring.
Do not change the brand, generic formulation, or dosage of this medication without first talking to your doctor.
Carry or wear a medical identification tag to let others know that you are taking this medicine in the case of an emergency.
Before taking this medication, tell your doctor if you have kidney or liver disease. You may not be able to take mephenytoin, or you may require a lower dose or special monitoring during treatment.
Mephenytoin may increase blood sugar. If you are a diabetic and are taking mephenytoin, watch for changes in your blood sugar levels that may be caused by this medication.Mephenytoin is in the FDA pregnancy category C. This means that it is not known whether mephenytoin will harm an unborn baby. Do not take mephenytoin without first talking to your doctor if you are pregnant. Mephenytoin passes into breast milk and may affect a nursing infant. Do not take mephenytoin without first talking to your doctor if you are breast-feeding a baby.
Take mephenytoin exactly as directed by your doctor. If you do not understand these directions, ask your pharmacist, nurse, or doctor to explain them to you.Take each dose of mephenytoin with a full glass of water. Take mephenytoin with food to lessen stomach upset
Do not change the brand name, generic formulation, or dosage of mephenytoin that you are taking without first talking to your doctor.
Carry or wear a medical identification tag to let others know that you are taking this medicine in the case of an emergency.Do not stop taking your medication even if you feel better. It is important to continue taking mephenytoin to prevent your seizures from recurring.
Do not take any tablet that is discolored.
Store this medication at room temperature away from light and moisture.
Take the missed dose as soon as you remember. However, if it is almost time for your next dose, skip the dose you missed and take only your next regularly scheduled dose. Do not take a double dose of this medication.
Symptoms of a mephenytoin overdose include back-and-forth eye movements, slurred speech, stumbling or staggering walk, imbalance, drowsiness, unconsciousness, nausea, vomiting, tremor, low blood pressure, and slow breathing.
an allergic reaction (difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives);
slurred speech or staggering walk;
changes in vision;
yellow skin or eyes (jaundice);
easy bruising or bleeding; or
swollen or tender gums.
Other, less serious side effects may be more likely to occur. Continue to take mephenytoin and talk to your doctor if you experience
nausea, vomiting, constipation, or diarrhea;
mild dizziness or drowsiness;
tender or swollen glands;
increased facial hair;
swelling of the breasts; or
Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.
The following drugs can increase the level of mephenytoin in your blood and cause dangerous side effects:
alcohol, when drunk occasionally;
other seizure medicines such as ethosuximide (Zarontin), methsuximide (Celontin Kapseals), and phensuximide (Milontin Kapseals);
the stomach medicines cimetidine (Tagamet, Tagamet HB), ranitidine (Zantac, Zantac 75), nizatidine (Axid, Axid AR), and famotidine (Pepcid, Pepcid AC);
the anxiety and insomnia medicines chlordiazepoxide (Librium, Librax) and diazepam (Valium);
estrogens such as conjugated estrogens (Premarin, PMB, Premphase, Prempro), estradiol (Estrace), esterified estrogens (Estratab, Estratest, Menest, estropipate (Ogen), and estrogen patches (Estraderm, Vivelle, Climara);
the heart medicine amiodarone (Cordarone);
salicylates such as aspirin (ASA), magnesium salicylate (Magan), choline salicylate (Arthropan), and choline magnesium trisalicylate (Trilisate);
anti-infective medicines such as isoniazid (INH) and sulfonamides such as sulfamethoxazole (Septra, Bactrim);
trazodone (Desyrel); and
Other drugs may decrease the amount of mephenytoin in your blood. This can decrease the effects of mephenytoin and result in seizures. The following drugs may have this effect:
alcohol, when drunk chronically (regularly);
the seizure medicine carbamazepine (Tegretol);
the heart medicine reserpine (Serpasil);
the stomach medicine sucralfate (Carafate); and
the psychiatric medicine molindone (Moban).
Other seizure medicines may interact unpredictably with mephenytoin and either increase or decrease its effects. These drugs include valproic acid (Depakene), divalproex sodium (Depakote), and phenobarbital (Luminal, Solfoton). It may be necessary to adjust your mephenytoin dosage.
Mephenytoin may also decrease the activity of other medicines including
steroid medicines, such as prednisone (Deltasone), hydrocortisone (Cortef), betamethasone (Celestone), dexamethasone (Decadron), methylprednisolone (Medrol), and others;
the blood thinner warfarin (Coumadin);
the heart medicine quinidine (Cardioquin, Quinora, Quinidex, others);
birth control pills and estrogens such as Premarin, Ogen, Estratab, Menest, Estratest, Estraderm, Vivelle, Climara, and others;
the anti-infective medicines rifampin (Rimactane, Rifadin) and doxycycline (Doryx, Vibramycin, Doxy, Monodox, others);
the diuretic (water pill) furosemide (Lasix); and
the asthma medicine theophylline (Theo-Dur, Theochron, Theo-Bid, Theolair, others).
Drugs other than those listed here may also interact with mephenytoin. Talk to your doctor and pharmacist before taking any prescription or over-the-counter medicines.
Mephenytoin is available with a prescription under the brand name Mesantoin. Other brand or generic formulations may also be available. Ask your pharmacist any questions you have about this medicine, especially if it is new to you.
Mesantoin 100 mg--speckled, pale-pink, round, scored tablets