zafirlukast

Antagonizes the effects of leukotrienes, which are components of slow-reacting substance of anaphylaxis.
These substances mediate the following:
- Airway edema,
- Smooth muscle constriction,
- Altered cellular activity.
Result is decreased inflammatory process that is part of asthma.

Therapeutic effects:

Decreased frequency and severity of asthma episodes.

Pharmacokinetics ⬆ ⬇

Absorption: Rapidly absorbed after oral administration.

Distribution: Enters breast milk.

Protein Binding: 99%.

Metabolism/Excretion: Mostly metabolized by the liver; 10% excreted unchanged by the kidneys.

Half-Life: 10 hr.

Time/Action Profile ⬆ ⬇

(improved symptoms of asthma)

ROUTE	ONSET	PEAK	DURATION
PO	unknown	1 wk	unknown

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity;
Hepatic impairment;
Lactation: Lactation.

Use Cautiously in:

Acute attacks of asthma;
Patients >55 yr (↑ risk of infection);
OB: Safety not established in pregnancy;
Pedi: Children <5 yr (safety and effectiveness not established);
Geri: May need lower doses in older adults to avoid side effects.

Adv. Reactions/Side Effects ⬆ ⬇

GI: abdominal pain, diarrhea, dyspepsia, HEPATOTOXICITY, nausea, vomiting

MS: arthralgia, back pain, myalgia

Neuro: headache, agitation, aggression, anxiety, depression, dizziness, dream abnormalities, hallucinations, insomnia, irritability, restlessness, SUICIDAL THOUGHTS, tremor, weakness

Misc: CHURG-STRAUSS SYNDROME, fever, infection (older adults)

Interactions ⬆ ⬇

Drug-drug:

Levels are ↑ by aspirin and fluconazole.
Levels are ↓ by erythromycin and theophylline.
↑effects and risk of bleeding with warfarin.

Drug-Food:

Food (especially high-fat or high-protein meal) ↓ absorption.

Route/Dosage ⬆ ⬇

PO (Adults and Children ≥12 yr): 20 mg twice daily.
PO (Children 5–11 yr): 10 mg twice daily.

Availability ⬆ ⬇

(Generic available)

Tablets: 10 mg; 20 mg

Assessment ⬆ ⬇

Assess lung sounds and respiratory function before and periodically during therapy.
Monitor closely for changes in behavior that could indicate the emergence or worsening of depression or suicidal thoughts.

Lab Test Considerations:

Monitor liver function periodically during therapy. May cause ↑ ALT concentrations. If liver impairment occurs, zafirlukast should be discontinued.

Implementation ⬆ ⬇

PO: Administer at regular intervals on an empty stomach, 1 hr before or 2 hr after meals.

Patient/Family Teaching ⬆ ⬇

Instruct patient to take medication on an empty stomach as directed, at evenly spaced intervals, even if not experiencing symptoms of asthma. Take missed doses as soon as remembered unless almost time for next dose. Do not double doses. Do not discontinue therapy without consulting health care professional.
Instruct patient not to discontinue or reduce other asthma medications without consulting health care professional.
Advise patient that zafirlukast is not used to treat acute asthma attacks but may be continued during an acute exacerbation.
Advise patient, family, and caregivers to look for suicidality, especially during early therapy or dose changes. Notify health care professional immediately if thoughts about suicide or dying, attempts to commit suicide, new or worse depression or anxiety, agitation or restlessness, panic attacks, insomnia, new or worse irritability, aggressiveness, acting on dangerous impulses, mania, or other changes in mood or behavior occur.
Advise patient to notify health care professional if symptoms of Churg-Strauss syndrome (generalized flu-like syndrome, fever, muscle aches and pain, weight loss, worsening respiratory symptoms) occur. Occurs rarely but may be life-threatening. More likely to occur when weaning from systemic corticosteroids.
Rep: Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected and to avoid breastfeeding during therapy.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇