Other commonly used names for trimethadione are TMO; trimethadionum; trimethinum; troxidone.

• Anticonvulsant --Paramethadione; Trimethadione

Dione anticonvulsants are used to control certain types of seizures in the treatment of epilepsy. They act on the central nervous system (CNS) to reduce the number of seizures. These medicines cannot cure epilepsy and will only work to control seizures for as long as you continue to take them.

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For dione anticonvulsants, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to anticonvulsant medicines. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—There have been reports of increased birth defects when dione anticonvulsants were used during pregnancy. The use of an effective method of birth control is recommended during treatment with dione anticonvulsants. Be sure you have discussed this with your doctor before taking this medicine. Dione anticonvulsants may also cause a bleeding problem in the mother during delivery and in the newborn. Doctors can help prevent this by giving vitamin K to the mother before and during delivery, and to the baby immediately after birth.

Breast-feeding—It is not known whether this medicine passes into breast milk. However, dione anticonvulsants may have serious unwanted effects, and breast-feeding is not recommended.

Children—Although there is no specific information comparing use of dione anticonvulsants in children with use in other age groups, these medicines are not expected to cause different side effects or problems in children than they do in adults.

Older adults—This medicine has been tested in a very small number of older people. Dione anticonvulsants are removed from the body more slowly in older people than in younger people. Higher blood levels of the medicine may occur, which may increase the chance of unwanted effects. Your doctor may give you a different dose than a younger person would receive.

Other medicines—Although certain medicines should not be used together at all, in other cases 2 different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking dione anticonvulsants, it is especially important that your health care professional know if you are taking any of the following:

• Central nervous system (CNS) depressants (medicine that causes drowsiness) or
• Tricyclic antidepressants (medicine for depression)—Using these medicines together may increase the CNS depressant effects

• Blood disease or
• Diseases of the eye or optic nerve or
• Kidney disease or
• Liver disease—Dione anticonvulsants may make the condition worse. Liver disease may cause higher blood levels of this medicine, which may increase the chance of side effects

• Porphyria—Trimethadione may make the condition worse

For patients taking paramethadione capsules:

• Swallow the capsules whole. Do not crush, chew, or break them before swallowing.

For patients taking trimethadione solution:

• Use a specially marked measuring spoon, a plastic syringe, or a small marked measuring cup to measure each dose accurately. The average household teaspoon may not hold the right amount of liquid.

For patients taking trimethadione chewable tablets :

• The tablets should be crushed and dissolved in a small amount of water or chewed before they are swallowed.

If this medicine upsets your stomach, take it with a small amount of food or milk unless otherwise directed by your doctor.

Take this medicine only as directed by your doctor , to benefit your condition as much as possible. Do not take more or less of it and do not take it more or less often than your doctor ordered.

Dosing—

The dose of dione anticonvulsants will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of paramethadione and trimethadione. If your dose is different, do not change it unless your doctor tells you to do so.

The number of tablets or capsules or teaspoonfuls of solution that you take depends on the strength of the medicine.

For paramethadione
• For oral dosage forms (capsules):
  • Adults and teenagers: To start, 300 milligrams (mg) three times a day. Your doctor may increase your dose by 300 mg every week until seizures are controlled or side effects appear. However, the dose is usually not more than 2400 mg a day, taken in three or four smaller doses.
  • Children 6 years of age and over: 300 mg three times a day.
  • Children 2 to 6 years of age: 200 mg three times a day.
  • Children up to 2 years of age: 100 mg three times a day.

For trimethadione
• For oral dosage forms (capsules, solution, tablets):
  • Adults and teenagers: To start, 300 milligrams (mg) three times a day. Your doctor may increase your dose by 300 mg every week until seizures are controlled or side effects appear. However, the dose is usually not more than 2400 mg a day, taken in three or four smaller doses.
  • Children 6 years of age and over: 300 mg three or four times a day.
  • Children 2 to 6 years of age: 200 mg three times a day.
  • Children up to 2 years of age: 100 mg three times a day.

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. If only one dose is missed, it may be taken at bedtime.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store the capsule form of this medicine in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Store trimethadione chewable tablets in the refrigerator.
• Keep the liquid form of this medicine from freezing.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

It is very important that your doctor check your progress at regular visits. This is necessary to allow dose adjustments and to test for serious unwanted effects.

Tell your doctor as soon as possible if you have a sore throat, fever, or general feeling of tiredness, or if you notice any unusual bleeding or bruising, such as red or purple spots on the skin, nosebleed, or bleeding gums.

Dione anticonvulsants may cause your eyes to become more sensitive to bright light than they are normally, making it difficult for you to see well. Wearing sunglasses and avoiding too much exposure to bright light may help lessen the discomfort. You may also have difficulty seeing in light that changes in brightness. If you notice this effect, be especially careful when driving at night.

This medicine will add to the effects of alcohol and other CNS depressants (medicines that slow down the nervous system, possibly causing drowsiness). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds; sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; barbiturates; medicine for seizures; muscle relaxants; or anesthetics, including some dental anesthetics. Check with your doctor before taking any of the above while you are using this medicine.

Dione anticonvulsants may cause some people to become drowsy or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are not alert. After you have taken this medicine for a while, this effect may not be so bothersome.

Before having any kind of surgery, dental treatment, or emergency treatment, tell the medical doctor or dentist in charge that you are taking this medicine. Taking dione anticonvulsants together with medicines that are used during surgery or dental or emergency treatments may increase the CNS depressant effects.

Check with your doctor as soon as possible if you suspect you have become pregnant.

Do not stop taking dione anticonvulsant medicines without first checking with your doctor. Your doctor may want to reduce your dose gradually. Stopping this medicine suddenly may cause seizures.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• More common
  • Changes in vision, especially night blindness, glare or snowy image caused by bright light, or double vision 
  
  

• Rare
  • Confusion;  convulsions (seizures);  dark or cloudy urine;  dizziness;  fever;  loss of appetite or weight;  muscle weakness (severe), especially drooping eyelids, or difficulty in chewing, swallowing, talking, or breathing;  nausea or vomiting;  pain in abdomen, chest, muscles or joints ;  shortness of breath;  skin rash or itching;  sore throat and fever;  swelling of face, hands, legs, and feet;  swollen lymph nodes;  unusual bleeding or bruising, such as recurring nosebleeds, bleeding gums, or vaginal bleeding, or red or purple spots on skin;  unusual tiredness or weakness ;  yellow eyes or skin 
  
  

• Symptoms of overdose
  • Clumsiness or unsteadiness;  coma;  dizziness (severe);  drowsiness (severe) ;  nausea (severe);  problems with vision 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Dizziness;  drowsiness;  headache;  increased sensitivity of eyes to light;  irritability 
  
  

• Less common
  • Behavior or mood changes;  blood pressure changes;  hair loss;  hiccups ;  loss of appetite;  stomach pain, nausea, or vomiting;  tingling, burning, or prickly sensations;  trouble in sleeping;  unusual weight loss 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.