Zafirlukast

Asthma Prevention

Zafirlukast is used for the chronic treatment and prevention of asthma in adults and children 5 years of age and older. It is designed to help manage and reduce the frequency of asthma symptoms, including:

• Wheezing
• Shortness of breath
• Chest tightness
• Coughing

Long-Term Control

This medication is intended for long-term use and must be taken consistently to be effective. It is not a rescue medication and will not work fast enough to stop an asthma attack that has already begun. For sudden breathing problems, a separate quick-relief inhaler is required.

Mechanism of Action

Zafirlukast belongs to a class of medications known as leukotriene receptor antagonists. It works by interfering with the activity of leukotrienes, which are chemicals the body releases when it encounters an asthma trigger, such as pollen, pet dander, or cold air.

When leukotrienes are released, they cause several physical reactions in the respiratory system:

• Airway Swelling: They cause inflammation and swelling in the lining of the lungs.
• Muscle Tightening: They cause the muscles surrounding the airways to constrict, making the passages narrower.
• Mucus Production: They increase the production of fluid and mucus in the lungs.

Zafirlukast works by binding to the receptors that these chemicals normally use. By blocking these receptors, the medication prevents leukotrienes from causing inflammation and constriction. This helps keep the airways open and reduces the frequency and severity of asthma symptoms like wheezing, coughing, and shortness of breath.

It is important to note that zafirlukast is a maintenance medication designed for long-term prevention. Because it works by blocking the biological pathway of inflammation rather than providing immediate muscle relaxation, it will not stop an asthma attack that has already started.

Common Side Effects

Some people may experience mild side effects while taking zafirlukast. These often include:

• Headache
• Nausea or diarrhea
• Stomach pain
• Dizziness
• Back pain or muscle aches
• Symptoms of a cold, such as a sore throat or sneezing

Serious Side Effects

Seek medical attention immediately if you experience any of the following serious symptoms:

Liver Problems

• Yellowing of the eyes or skin (jaundice)
• Dark-colored urine
• Pain in the upper right part of the stomach
• Loss of appetite or extreme tiredness

Mood and Behavior Changes

Zafirlukast may cause mental health changes. Notify a healthcare provider right away if you notice:

• Agitation, aggression, or irritability
• Anxiety or depression
• Difficulty sleeping or unusual dreams
• Confusion or tremors
• Suicidal thoughts or behaviors

Other Serious Symptoms

• Signs of an allergic reaction, such as a severe rash, hives, or swelling of the face and throat
• Numbness or a tingling sensation in the arms or legs
• Severe sinus pain, swelling, or burning

Acute Asthma Attacks

Zafirlukast is not a rescue medication. It should not be used to treat a sudden asthma attack or status asthmaticus. Patients must continue to have their fast-acting rescue inhaler available for acute symptoms.

Liver Toxicity

Cases of severe liver injury, including hepatic failure and hepatitis, have been reported in patients taking this medication. Healthcare providers may perform blood tests to monitor liver function before and during treatment. Signs of liver problems include:

• Yellowing of the skin or eyes (jaundice)
• Dark-colored urine
• Pain in the upper right side of the abdomen
• Unexplained nausea, fatigue, or loss of appetite

Neuropsychiatric Events

Some patients taking leukotriene receptor antagonists have experienced mood or behavior changes. These may include agitation, aggression, anxiety, depression, abnormal dreams, or suicidal thoughts. If these symptoms occur, medical attention should be sought immediately.

Eosinophilic Conditions

In rare cases, patients with asthma may develop systemic eosinophilic vasculitis, also known as Churg-Strauss syndrome. This often occurs when oral corticosteroid dosages are being reduced. Symptoms may include a rash, worsening pulmonary symptoms, cardiac complications, or nerve pain.

Drug Interactions

Zafirlukast can interact with other medications, potentially changing how they work or increasing side effects. Notable interactions include:

• Warfarin: Zafirlukast may significantly increase the effects of blood thinners, increasing the risk of bleeding.
• Theophylline: This may decrease the effectiveness of zafirlukast.
• Aspirin: Taking aspirin may increase the levels of zafirlukast in the blood.

Pregnancy

There are no adequate and well-controlled studies of zafirlukast in pregnant women. Animal research involving high doses of the medication did not show evidence of harm to the fetus; however, animal studies do not always predict human response. This medication should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. It is important to inform your healthcare provider if you are pregnant or planning to become pregnant while taking this medication.

Breastfeeding

Zafirlukast is known to pass into human breast milk. Because of the potential for serious adverse reactions in nursing infants, a decision must be made whether to stop breastfeeding or stop taking the medication. Healthcare providers will typically weigh the importance of the drug to the mother against the potential risks to the infant when making this recommendation. You should consult your doctor if you are breastfeeding or plan to breastfeed.

Available Forms

Zafirlukast is manufactured as a tablet for oral administration. It is available as both a brand-name medication and as a generic drug.

• Oral tablet

FDA Approval and Indications

Zafirlukast was first approved by the U.S. Food and Drug Administration (FDA) in 1996. It is indicated for the prophylaxis and chronic treatment of asthma. It is important to note that zafirlukast is not indicated for the reversal of bronchospasm in acute asthma attacks, including status asthmaticus.

Regulatory Safety Information

The FDA-approved labeling for zafirlukast includes several important safety warnings and precautions:

• Hepatotoxicity: Cases of liver injury, including symptomatic hepatitis and liver failure, have been reported. Healthcare providers may monitor liver function through blood tests during treatment.
• Neuropsychiatric Events: While zafirlukast does not carry the same boxed warning as montelukast, reports of neuropsychiatric events such as insomnia, agitation, and depression have been documented. Patients should be monitored for changes in behavior or mood.
• Eosinophilic Conditions: In rare cases, patients may present with systemic eosinophilia, sometimes presenting with clinical features of vasculitis consistent with Churg-Strauss syndrome.

Generic Availability

Zafirlukast is available as a generic medication. Generic versions are required to meet the same FDA standards for bioequivalence, quality, and strength as the original brand-name version, Accolate.

Generic Availability

Zafirlukast is available as a generic medication. Generic drugs are required to meet the same quality and safety standards as brand-name versions but are usually available at a lower cost.

Insurance Coverage

Most insurance plans provide coverage for the generic form of zafirlukast. Out-of-pocket expenses will depend on the individual's insurance policy, including specific copay tiers or deductibles.

Cost Factors

The price of zafirlukast may vary depending on the pharmacy used. Patients are encouraged to compare prices at different locations or inquire about prescription discount programs that may help reduce the total cost.