Zafirlukast: An Update of its Pharmacology and Therapeutic Efficacy in Asthma

Authors: Dunn C.J.; Goa K.L.

Source: Drugs, Volume 61, Number 2, 2001 , pp. 285-315(31)

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Abstract:

Zafirlukast is a selective and competitive orally administered inhibitor of the cysteinyl leukotrienes LTC, LTD and LTE. The drug is indicated for the prophylaxis and treatment of chronic asthma, and has been developed in response to mounting evidence indicating the importance of the cysteinyl leukotrienes in the pathogenesis of this disorder.

The efficacy of zafirlukast 20mg twice daily has been shown in double-blind placebo-controlled studies of up to 13 weeks' duration in patients aged 12 years. Zafirlukast was consistently superior to placebo in improving objective measures of lung function and subjective measures such as symptom scores and use of as-required bronchodilator therapy. This dosage is also as effective when added to low-dosage inhaled corticosteroid therapy as doubling of corticosteroid dosages. Recent studies indicate superior efficacy over zafirlukast of twice-daily inhaled fluticasone propionate 88µg or salmeterol 42µg, although zafirlukast was nevertheless associated with clinical improvement. Data also show zafirlukast 40mg to be of similar efficacy to pranlukast 225mg (both twice daily).

Overall, preliminary pharmacoeconomic data suggest that healthcare costs are reduced by zafirlukast therapy, although superior cost effectiveness has been reported with inhaled fluticasone propionate, and further studies are needed. Data are available to show improvements in patient-rated quality of life, and preference for and high rates of compliance with zafirlukast.

In clinical trials, zafirlukast has shown an adverse event profile similar to that of placebo. Isolated reports of hepatic dysfunction in a small number of individuals receiving the drug have been received, and recommendations for monitoring of patients are in place. Although no causal relationship has been established between zafirlukast and Churg-Strauss Syndrome, patients undergoing corticosteroid dosage reductions require careful surveillance.

Conclusions: zafirlukast is an effective and well tolerated agent for preventive monotherapy in mild to moderate persistent asthma. Emerging data indicate benefit of the drug when added to low-dosage inhaled corticosteroids and show that it may be a viable alternative to inhaled adjunctive treatments and increased corticosteroid dosages in some patients. Although inhaled fluticasone propionate and salmeterol have been associated with greater clinical improvement than zafirlukast in clinical studies, compliance considerations and the confirmed clinical efficacy relative to placebo of the drug denote zafirlukast as an effective alternative in treatment programmes based on individualised therapy. As experience with zafirlukast accumulates, it is expected that the drug will be positioned more definitively in national and international treatment guidelines.

Keywords: Antiasthmatics, general; Asthma, treatment; Drug evaluations; Leukotriene antagonists, general; Zafirlukast, general

Language: English

Document Type: Drug Evaluation

Affiliations: 1: Adis International Limited, Auckland, New Zealand *

Publication date: 2001-01-01

Zafirlukast: An Update of its Pharmacology and Therapeutic Efficacy in Asthma

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