Zafirlukast

Oral
Chronic asthma

Contraindicated.

Should be taken on an empty stomach. Take at least 1 hr before or 2 hr after meals.

Hepatic impairment including hepatic cirrhosis.

Not indicated for use in the reversal of bronchospasm in acute asthma attacks. Avoid abruptly substitution to oral or inhaled corticosteroids. Renal impairment. Pregnancy and lactation.

Systemic eosinophilia, eosinophilic pneumonia or w/ clinical features of systemic vasculitis consistent w/ Churg-Strauss syndrome; neuropsychiatric adverse events (e.g. insomnia, depression); headache, resp tract infection, GI disturbances, arthralgia, myalgia, fever, malaise, insomnia, dizziness, elevated liver enzyme values, hypersensitivity reactions (e.g. rashes, pruritus, urticaria, angioedema), agranulocytosis, bleeding, bruising, oedema.
Potentially Fatal: Severe hepatotoxicity.

PO: B

Monitor for improvements in air flow; monitor closely for sign/symptoms of hepatic injury; periodic monitoring of LFTs.

Symptoms: Rash and stomach upset. Management: Supportive and symptomatic treatment. Empty the stomach by inducing emesis or by gastric lavage. May administer activated charcoal to prevent absorption of unrecovered drug.

May enhance anticoagulant activity of warfarin resulting to increased prothrombin time. Decreased plasma levels w/ theophylline, terfenadine and erythromycin. Increased plasma levels w/ fluconazole and high dose aspirin.

Food reduces the rate and extent of absorption.

Description: Zafirlukast is a selective and competitive leukotriene-receptor antagonist (LTRA) of leukotriene D4 and E4 (LTD4 and LTE4), components of slow-reacting substance of anaphylaxis (SRSA). Cysteinyl leukotriene production and receptor occupation have been correlated w/ the pathophysiology of asthma, including airway oedema, smooth muscle constriction, and altered cellular activity associated w/ the inflammatory process, which contribute to the signs and symptoms of asthma.
Pharmacokinetics:
Absorption: Rapidly absorbed from the GI tract. Food reduces the rate and extent of absorption. Time to peak plasma concentration: Approx 3 hr.
Distribution: Volume of distribution: Approx 70 L. Plasma protein binding: Approx 99% (primarily to albumin).
Metabolism: Extensively metabolised in the liver, mainly by CYP2C9 isoenzyme.
Excretion: Mainly via faeces (approx 90%) as unchanged drug and metabolites and urine (approx 10%) as metabolites. Terminal elimination half-life: Approx 10 hr.

Source: National Center for Biotechnology Information. PubChem Database. Zafirlukast, CID=5717, https://pubchem.ncbi.nlm.nih.gov/compound/Zafirlukast (accessed on Jan. 24, 2020)

Store between 20-25°C. Protect from light and moisture.

Antiasthmatic & COPD Preparations

Accolate Tablet. U.S. FDA. https://www.fda.gov/. Accessed 30/09/2014.

Anon. Zafirlukast. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 01/10/2014.

Buckingham R (ed). Zafirlukast. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 30/09/2014.

McEvoy GK, Snow EK, Miller J et al (eds). Zafirlukast. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 30/09/2014.

Zafirlukast Tablet, Film-Coated (AstraZeneca Pharmaceuticals LP). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 30/09/2014.