Methsuximide

Unless your doctor tells you otherwise, continue your normal diet.

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your response to methsuximide.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

• Celontin^®

Contraindications

Hypersensitivity

Cautions

Do not discontinue rapidly

Succinimides have been associated with blood dyscrasias

Pregnancy Category: C

Lactation: avoid during breastfeeding

Pregnancy Categories

A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA:Information not available.

Methsuximide is an anti-epileptic medication, also called an anticonvulsant.

Methsuximide is used alone or in combination with other medications to treat absence seizures (also called "petit mal" seizures) in adults and children.

Methsuximide may also be used for purposes not listed in this medication guide.

Taking this medicine with other drugs that make you dizzy or sleepy can worsen this effect. Ask your doctor before taking methsuximide with a sleeping pill, narcotic pain medicine, muscle relaxer, or medicine for anxiety, depression, or seizures.

Tell your doctor about all your current seizure medications, and any you start or stop using.

Other drugs may interact with methsuximide, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Use this medicine as ordered by your doctor. Read all information given to you. Follow all instructions closely.

• Take with or without food. Take with food if it causes an upset stomach.
• Do not take capsules that are not full or capsules where the contents have melted.
• To gain the most benefit, do not miss doses.
• Keep taking methsuximide as you have been told by your doctor or other health care provider, even if you feel well.
• Take this medicine at the same time of day.
• Do not change the dose or stop methsuximide. This could cause seizures. Talk with your doctor.

What do I do if I miss a dose?

• Take a missed dose as soon as you think about it.
• If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
• Do not take 2 doses at the same time or extra doses.

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Capsule, Oral:

Celontin: 300 mg

Increases the seizure threshold and suppresses paroxysmal spike-and-wave pattern in absence seizures; depresses nerve transmission in the motor cortex

Metabolism

Metabolism: Hepatic; rapidly demethylated to N-desmethylmethsuximide (active metabolite)

Excretion

Urine (<1% as unchanged drug)

Time to Peak

Serum: 1 to 3 hours

Half-Life Elimination

2 to 4 hours

N-desmethylmethsuximide: Children: 26 hours; Adults: 28 to 80 hours

Absence (petit mal) seizures, refractory: Control of absence (petit mal) seizures that are refractory to other drugs

Absence (petit mal) seizures, refractory: Oral: 300 mg daily for the first week; may increase by 300 mg/day at weekly intervals up to 1.2 g/day in 2 to 4 divided doses; slower titrations may be considered to avoid toxic accumulation of active metabolite (N-desmethylmethsuximide) (Brown 1983).

Store at 25°C (77°F); excursions permitted to 15°C to 30°C (59°F to 86°F); protect from excessive heat 40°C (104°F). Protect from light and moisture. Note: Methsuximide has a relatively low melting temperature (124°F); do not store in conditions that promote high temperatures (eg, in a closed vehicle).

Frequency not defined.

Cardiovascular: Hyperemia

Central nervous system: Aggressiveness, ataxia, confusion, depression, dizziness, drowsiness, hallucinations (auditory), headache, hypochondriacal behavior, insomnia, irritability, mental instability, mental slowness, nervousness, psychosis, suicidal behavior

Dermatologic: Pruritus, rash, Stevens-Johnson syndrome, urticaria

Gastrointestinal: Abdominal pain, anorexia, constipation, diarrhea, epigastric pain, nausea, vomiting, weight loss

Genitourinary: Hematuria (microscopic), proteinuria

Hematologic: Eosinophilia, leukopenia, monocytosis, pancytopenia

Ocular: Blurred vision, periorbital edema, photophobia

Miscellaneous: Hiccups, systemic lupus erythematosus

Concerns related to adverse effects:

• Blood dyscrasias: Succinimides have been associated with severe blood dyscrasias (sometimes fatal). Monitor blood counts periodically, especially if signs/symptoms of infection develop.

• CNS depression: May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving).

• SLE: Succinimides have been associated with cases of systemic lupus erythematosus (SLE).

• Suicidal ideation: Pooled analysis of trials involving various antiepileptics (regardless of indication) showed an increased risk of suicidal thoughts/behavior (incidence rate: 0.43% treated patients compared to 0.24% of patients receiving placebo); risk observed as early as 1 week after initiation and continued through duration of trials (most trials ≤24 weeks). Monitor all patients for notable changes in behavior that might indicate suicidal thoughts or depression; notify healthcare provider immediately if symptoms occur.

Disease-related concerns:

• Hepatic impairment: Use with caution in patients with hepatic impairment.

• Renal impairment: Use with caution in patients with renal impairment.

Concurrent drug therapy issues:

• Sedatives: Effects with other sedative drugs or ethanol may be potentiated.

Other warnings/precautions:

• Appropriate use: Must be used in combination with other anticonvulsants in patients with both absence and tonic-clonic seizures. May increase tonic-clonic seizures when used alone in patients with mixed seizure disorders.

• Withdrawal: Anticonvulsants should not be discontinued abruptly because of the possibility of increasing seizure frequency; therapy should be withdrawn gradually to minimize the potential of increased seizure frequency, unless safety concerns require a more rapid withdrawal.

Applies to methsuximide: oral capsule

Along with its needed effects, methsuximide 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 immediately if any of the following side effects occur while taking methsuximide:

• Attempts at killing oneself
• feeling that others are watching you or controlling your behavior
• feeling that others can hear your thoughts
• feeling, seeing, or hearing things that are not there
• severe mood or mental changes
• unusual behavior

• Attack, assault, or force
• blistering, peeling, or loosening of the skin
• blood in the urine
• bloody, black, or tarry stools
• chest pain
• chills
• cloudy urine
• cough or hoarseness
• diarrhea
• discouragement
• feeling sad or empty
• fever
• high fever
• irritability
• itching
• joint or muscle pain
• lack of appetite
• loss of interest or pleasure
• lower back or side pain
• mood or mental changes
• nervousness
• painful or difficult urination
• pale skin
• red skin lesions, often with a purple center
• red, irritated eyes
• shakiness and unsteady walk
• shortness of breath
• sore throat
• sores, ulcers, or white spots on the lips or in the mouth
• swelling around the eyes
• swollen glands
• tiredness
• trouble with concentrating
• trouble with sleeping
• unexplained bleeding or bruising
• unsteadiness, trembling, or other problems with muscle control or coordination
• unusual bleeding or bruising
• unusual tiredness or weakness
• vision changes

Get emergency help immediately if any of the following symptoms of overdose occur while taking methsuximide:

• Change in consciousness
• difficult or troubled breathing
• irregular, fast or slow, or shallow breathing
• loss of consciousness
• pale or blue lips, fingernails, or skin

Some side effects of methsuximide may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

• Blurred vision
• change in color vision
• difficulty having a bowel movement (stool)
• difficulty seeing at night
• dizziness
• drowsiness
• heartburn
• hiccups
• hives or welts
• increased sensitivity of the eyes to sunlight
• loss of appetite
• nausea or vomiting
• pain or discomfort in the chest, upper stomach, or throat
• redness of the skin
• skin rash
• sleeplessness
• unable to sleep
• weight loss

Data not available

Treatment should proceed slowly when increasing or decreasing dosage as well as when adding or eliminating other medication. Abrupt withdrawal of anticonvulsant medications may precipitate petit mal status.

The smaller capsule (150 mg) facilitates administration to small children.