Zyflo CR (Oral)

Generic name: zileuton (oral route) [ zye-LOO-ton ]
Drug class: Leukotriene modifiers

Medically reviewed by Drugs.com. Last updated on Oct 14, 2022.

Commonly used brand name(s)

In the U.S.

• Zyflo
• Zyflo CR

Available Dosage Forms:

• Tablet
• Tablet, Extended Release

Therapeutic Class: Anti-Inflammatory

Pharmacologic Class: Leukotriene Pathway Inhibitor

Uses for Zyflo CR

Zileuton is used by patients with mild-to-moderate chronic asthma to decrease the symptoms of asthma and the number of acute asthma attacks. However, this medicine should not be taken to relieve an asthma attack that has already started.

This medicine is available only with your doctor''s prescription.

Zileuton immediate-release tablets (Zyflo(R)) were withdrawn from the U. S. market by Critical Therapeutics on February 12, 2008. The extended-release formulation of zileuton (Zyflo CR(R)), also manufactured by Critical Therapeutics, Inc, is still available.

Before using Zyflo CR

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 this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Appropriate studies have not been performed on the relationship of age to the effects of zileuton in children younger than 12 years of age. Safety and efficacy have not been established.

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of zileuton in the elderly. However, elderly patients are more likely to have age-related liver disease, and this medicine should not be used in patients with this condition.

Breastfeeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with medicines

Although certain medicines should not be used together at all, in other cases two 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 this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Amiodarone
• Anagrelide
• Astemizole
• Carbamazepine
• Ceritinib
• Clarithromycin
• Pimozide
• Piperaquine
• Pixantrone
• Propranolol
• Theophylline
• Tizanidine

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Warfarin

Interactions with food/tobacco/alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following is usually not recommended, but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco.

• Tobacco

Other medical problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Alcohol use, severe or
• Liver disease, history of—Use with caution. The chance of serious side effects may be increased.

• Liver disease, active—This medicine should not be used with this condition.

Proper use of Zyflo CR

This section provides information on the proper use of a number of products that contain zileuton. It may not be specific to Zyflo CR. Please read with care.

Zileuton is used to prevent asthma attacks. It is not used to relieve an attack that has already started. For relief of an asthma attack that has already started, you should use another inhaled medicine that works quickly. If you have any questions about this, check with your doctor.

Swallow the extended-release tablet whole. Do not crush, break, or chew it.

To work properly, zileuton must be taken every day at regularly spaced times, even if your asthma seems better.

Dosing

The dose of this medicine 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 this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For oral dosage form (extended-release tablets):
  • For asthma prevention:
    • Adults and children 12 years of age and older—Two 600 milligram (mg) tablets two times a day, within one hour after morning and evening meals.
    • Children up to 12 years of age—Use and dose must be determined by your doctor.

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. Do not double doses.

Storage

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Precautions while using Zyflo CR

It is very important that your doctor check your progress at regular visits. This will allow your doctor to see if the medicine is working properly and to check for unwanted effects.

Check with your doctor if you are using more inhalations (puffs) than usual of your inhaled bronchodilator to relieve an acute asthma attack.

You may be taking other medicines for asthma along with zileuton. Do not stop taking or reduce the dose of the other medicines, even if your asthma seems better, unless you are told to do so by your doctor.

You should limit the amount of alcohol you drink while you are taking this medicine.

This medicine may cause some people to be agitated, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed and have problems with sleep. If you or your caregiver notice any of these side effects, tell your doctor right away.

Zyflo CR side effects

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 immediately if any of the following side effects occur:

Rare

• Flu-like symptoms
• itching
• right upper stomach pain
• unusual tiredness or weakness
• yellow eyes or skin

Incidence not known

• Attack, assault, or force
• attempts at killing oneself
• discouragement
• dry mouth
• fear or nervousness
• feeling sad or empty
• hyperventilation
• irregular heartbeats
• irritability
• lack of appetite
• loss of interest or pleasure
• restlessness
• seeing, hearing, or feeling things that are not there
• shakiness in the legs, arms, hands, or feet
• shortness of breath
• sleeplessness
• tiredness
• trembling or shaking of the hands or feet
• trouble with concentrating
• trouble with sleeping
• unable to sleep

Some 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. 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:

More common

• Cough
• fever
• headache
• nausea
• pain or tenderness around the eyes and cheekbones
• stuffy or runny nose
• tightness of the chest or wheezing
• troubled breathing
• upset stomach

Less common

• Abdominal or stomach pain
• sore throat
• weakness

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

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer