Clobazam: Indications, Administration, Side Effects, Interactions and Recommendations

It is a benzodiazepine class drug used to control seizures.

Clobazam (KLOH-bah-ZAM) is the generic name for brand name drugs such as Onfi ® and Sympazan ™ in the United States and Frisium (FRIH-Zee-um) in some other countries.

The name or appearance of the medicine may be different for generic forms of clobazam.

Clobazam is approved for the additional treatment of seizures in children 2 years of age and older and in adults with types of seizures that may be associated with Lennox-Gastaut syndrome (LGS).


Clobazam is sold in the United States by Lundbeck as Onfi. Onfi is available in the United States as 10 mg and 20 mg tablets, as well as 2.5 mg / ml oral suspension.

The name or appearance may differ from country to country, but the dose (measured in milligrams, “mg” for short) will generally be the same.


10 mg. Oval in shape, white to off-white in color, scored so that it can be broken in half. Tablets marked with a “1” and a “0” on one side.

20 mg. Oval in shape, white to off-white in color, scored so that it can be broken in half. Tablets marked with a “2” and a “0” on one side.

Liquid solution

Each bottle is 120 ml, with 2.5 mg of clobazam per ml. It is whitish suspension, berry flavor. Dispenser with two syringes and a bottle adapter comes with each bottle.


Sympazan is an oral soluble formulation of clobazam that uses a new technology called PharmFilm ®. Instead of pills, the medicine is packaged in a film strip that dissolves once it is placed on the tongue.

This medicine can be used by anyone and is helpful for people who have trouble swallowing or difficulty taking oral tablets or liquids.

Three doses of sympazan film strips: 5mg, 10mg, 20mg, each with a berry flavor.

Used to treat

  • Lennox-Gastaut syndrome.
  • Absence seizures.
  • Atonic seizures.
  • Atypical absence seizures.
  • Impaired focal consciousness or complex partial seizures.
  • Myoclonic seizures.
  • Refractory seizures.
  • Generalized secondary seizures or bilateral tonic clonic seizures.
  • Focal Aware or simple partial seizure.
  • Tonic-clonic seizures.

How to take and store clobazam?

How to drink:

  • The prescribed dose of onfi and how to increase it can vary with a person’s body weight.
  •  For people who weigh less than 30 kg or 66 pounds, onfi usually starts at 5 mg per day. Increase as directed to 20 mg each day.
  • For people who weigh more than 30 kg or 66 pounds, the drug usually starts at 10 mg each day. Increase as directed to 40 mg each day.
  • Onfi is generally taken twice a day.
  • The dose usually increases once a week or more slowly. It takes 5 to 9 days for the dose to reach a stable state in the body.
  • Clobazam tablets should be swallowed whole, followed by at least half a glass of water. They can also be divided in half along the score or crushed and mixed with applesauce or other soft food.
  • Clobazam can be taken with or without food.
  • Do not stop taking this medicine suddenly. Stopping this medicine suddenly can cause seizures that won’t stop, hearing or seeing things that aren’t there, tremors, nervousness, or stomach and muscle cramps.

Use of the oral suspension:

  • If you are taking onfi oral suspension, shake the bottle well just before taking each dose.
  • Measure your dose of onfi oral suspension with the bottle adapter and the dosing syringes that come with the suspension.

Use of sympazan film formulation:

  • Open the package and take out the sympazan film strip.
  • Put it on your tongue and let it dissolve.
  • Use only one film strip at a time.
  • Do not use any liquid when putting the film on the tongue. It will dissolve on its own. If the filmstrip is swallowed by mistake, the medicine will still be absorbed into your system.
  • Sympazan can be taken before or after food, like other forms of clobazam.

How to store:

  • Store the tablets and oral film strips at room temperature in a dry place that is out of the reach of children.
  • Make sure to replace the cap securely after opening the oral suspension bottle and keep the bottle upright.
  • Also, use Onfi oral suspension within 90 days of first opening the bottle. Discard any unused Onfi suspension after this time.
What if I forget to take it?

Ask your doctor or nurse what to do if you forget to take a dose. In general, a missed dose should be taken right away. If it is almost time for your next dose, only take one dose, not a double dose, and call your doctor’s office for more advice.

Use a pillbox, watch with alarm, or an online diary or seizure device with reminders to help you take your dose on time.

How does clobazam affect the brain?

How clobazam works in the brain is not fully understood. It is believed to affect neurotransmitters or substances in the brain that affect the way brain cells communicate. It appears to involve or increase activity at GABA receptors in certain brain cells.

How does the body digest clobazam?

Clobazam is rapidly absorbed into the bloodstream. The amount peaks or reaches its highest level within 30 minutes to 4 hours after taking the dose.

Taking the medicine with or without food does not affect how it is absorbed into the body.

The drug is distributed throughout the body quickly. Most drugs are bound to protein as it circulates through the bloodstream.

Clobazam is metabolized or broken down in the liver to the main or main drug and breakdown products called metabolites. The main or main drug (clobazam) provides most of the activity in the brain to slow or stop seizures.

However, the main metabolite can also be active in the brain in smaller amounts.

Clobazam and its main metabolite last a long time in the body. The average half-life (or the time it takes for the body to get rid of half of the drug) for clobazam ranges from 36 to 42 hours. The metabolite can last longer in the body, up to 82 hours.

This long half-life means that it takes time for the medicine to reach a constant amount in the system (up to 2 to 3 weeks) and should not be stopped suddenly.

How well does clobazam work?

The package insert summarizes information from the major studies used by the FDA to approve this drug.

These studies have shown that clobazam can decrease the frequency of seizures in people with refractory or uncontrolled seizures, but does not completely control them.

The dose of clobazam used was significant. People who received the highest recommended dose had greater improvement in seizures than those who received a lower dose of clobazam.

What are the most common side effects of clobazam?

The side effects of clobazam are generally mild and usually go away if the dose is lowered. They can also go away over time as a person gets used to the medicine.

The most frequently reported side effects are:

  • Drowsiness.
  • Dizziness.
  • Poor coordination
  • Babeo.
  • Instability or aggressiveness.

What to do

If these problems do not go away in several days, or if they are really bothersome, call your doctor or health care professional who prescribes medicine. Sometimes the doctor can help with these side effects by changing the way the medicine is taken.

For example, you may be asked to:

  • The total amount of clobazam is reduced.
  • Change the amount taken at certain times, such as taking a larger amount of clobazam at bedtime to decrease daytime sleepiness.
  • Give smaller amounts more often throughout the day.
  • No one should stop taking clobazam or change the amount they take or when they take it without the advice of their doctor or prescriber.
  • Be sure to read about serious side effects so that you can be aware of symptoms that could indicate the beginning of a serious reaction to clobazam. These serious problems are very rare, but everyone taking this drug should at least be aware of them.
  • People who have just started taking clobazam (or who have just taken a larger amount) should be careful during potentially dangerous activities until they know if they are having any side effects.

Long-term side effects

Clobazam and other benzodiazepines are the drugs most likely to cause psychological dependence. When someone takes a benzodiazepine at a certain dose for more than 2 to 4 weeks, the body (or specifically, the brain’s receptors for the neurotransmitter GABA) get used to it.

Then, if a dose is missed or reduced, a withdrawal process begins, with symptoms such as:

  • Anxiety.
  • Incrise of cardiac frecuency.
  • Temblor.
  • Generally discomfort.

Taking another pill relieves all of these symptoms. A person may then believe that he or she “needs” the drug.

However, this is a very dangerous cycle, as long-term use can cause long-lasting changes in the brain’s GABA receptors that lead to significant problems, such as cognitive decline, decreased motivation, and depression.

In this context, lowering a dose quickly can cause severe symptoms of anxiety, insomnia, and illness, as well as seizures.

Many times, a very gradual decrease in benzodiazepine (often over many months or years) can lead to a dramatic improvement in attention, concentration, memory, and mood without worsening seizures, insomnia, or anxiety. which the drug was originally prescribed.

What are the most serious side effects of clobazam?

Most people who take clobazam have no side effects or mild side effects that go away in a short time without causing lasting damage. Serious reactions, such as a drug-related rash, have been extremely rare.

Call your doctor right away if you notice a rash shortly after you start taking clobazam.

Sleep or poor coordination

Like many other seizure medications, clobazam makes some people feel drowsy or uncoordinated.

If you have just started taking clobazam or have just increased your dose, be careful doing things that could be dangerous until you know how it will affect you.

Be especially careful if you tend to be sensitive to medications or if you are taking another medication that could make you sleepy.

Mood or thinking changes

One of the great dangers in the use of drugs like clobazam is the tendency to increase the dose if tolerance develops. To some extent, this is necessary, but the side effects can be increased more than seizure control.

If the dose is gradually increased over a long period, subtle changes in mood (such as irritability, depression, or decreased motivation) or problems such as impaired memory may go unnoticed or be considered natural for that person.

High doses are sometimes prescribed for children and adults, especially those with developmental disabilities. Problems with thinking and behavior can be the result.

If the dose has been gradually increased over many months or years, it can be difficult to separate the effects of clobazam (or other benzodiazepines) from the effects of other medications, seizures, and other neurological and psychological disorders.

More frequent seizures

A major concern when people with epilepsy take clobazam or other benzodiazepines is the risk that seizures will become more frequent or more severe if the drug is lowered or stopped.

Withdrawal syndrome usually begins as soon as the patient stops taking the drug and lasts between 8 and 10 days.

The longer you have been taking clobazam and the higher the dose, the greater the tolerance and therefore the greater the risk of worsening seizure control.

Even small gradual dose reductions can temporarily increase seizure activity, but the long-term decrease in effects such as drowsiness and depression often makes the switch worthwhile.

Suicidal thoughts or feelings

On July 10, 2008, an advisory committee was convened by the FDA to review data that the FDA had previously collected from drug studies showing an association between many of the antiepileptic drugs (AEDs) and suicidal ideation and behavior.

Those that together are called suicidality. According to the FDA Alert, among epilepsy patients in these drug studies, 1 in 1000 people who took the placebo (inactive substance) showed suicide compared to about 3.5 out of 1000 people who took an AED.

The FDA advisory panel voted to accept the FDA data at its July 10 meeting.

Taking antiepileptic drugs can increase the risk of having suicidal thoughts or actions.

Do not make any changes to your medication regimen without first talking to your responsible healthcare professional;

Pay close attention to any daily changes in mood, behavior, and actions. These changes can happen very quickly, so it is important to be aware of any sudden differences.

Be on the lookout for common warning signs that could be a sign of suicide risk.

 Some of them are:

  • Talking or thinking about wanting to hurt yourself or end your life.
  • Withdrawing from friends and family.
  • Get depressed or make your depression worse.
  • Worrying about death and dying.
  • Giving away prized possessions.

We again urge patients and families to contact their physician before stopping an epilepsy medication, as this can lead to seizures and worsening mood.

What else is clobazam used for?

Some evidence suggests efficacy against photosensitive epilepsy and myoclonic seizures.

Can clobazam be taken with other medicines?

Clobazam may interact with hormonal contraceptives or contraceptives, possibly making them less effective. Women of childbearing potential should talk with their healthcare providers about the best form of contraception for them.

Women using clobazam and taking hormonal contraceptives must use a barrier method of contraception.

Clobazam can affect some medications that are metabolized by certain liver enzymes.

Clobazam can also be affected by some other medications that inhibit or affect certain liver enzymes (eg, fluconazole, fluvoxamine, ticlopidine, omeprazole). The dose of clobazam may need to be adjusted.

See the package leaflet for more information on possible drug interactions.

Alcohol can also increase the amount of clobazam in the body by about 50%.

Recommendations about dosage

Young adults and adolescents are generally recommended to begin by taking 10 milligrams (1 tablet) per day, in the evening. After about a week, the doctor may prescribe more tablets to better control the seizures.

However, very few people benefit from taking more than 2 or 3 tablets (20-30 mg) per day, and the side effects generally become more troublesome with higher doses.

If the seizures almost always occur during sleep or first thing in the morning, the doctor may recommend taking all the tablets at bedtime. If seizures occur during the day, the advice may be to take them twice a day. If the dose cannot be divided evenly, take the largest amount at bedtime.

Older people (over 65 years of age) generally require a lower starting dose and special caution with any increase.

For children, the starting dose is usually half a tablet (5 mg) per day, or even less for very young children. The dose can be increased every 5 to 7 days until the seizures are controlled or side effects become a problem.

However, giving just over 1 mg per kilogram (2.2 pounds) of a child’s body weight per day rarely improves seizure control. This dose would represent 3 tablets (30 mg) for a 66 pound child or 2 tablets (20 mg) for a 44 pound child. These amounts are generally divided into two doses per day.

Make sure you only use the number of tablets that your doctor prescribes. If you think an extra pill or two were taken, see your doctor. For a major overdose, call your local poison control center or emergency room right away.

No one should stop taking clobazam or change the amount they take without talking to their doctor first. Stopping any seizure medicine at the same time can cause a serious problem called status epilepticus.

It is particularly dangerous to stop taking any type of benzodiazepine abruptly. The resulting withdrawal symptoms are likely to be unpleasant or even dangerous.