Last update March 3, 2022


Low Risk

Moderately safe. Probably compatible. Mild risk possible. Follow up recommended. Read the Comment.

It is a selective leukotriene receptor antagonist with actions and uses similar to those of montelukast. Used in the management of asthma. Oral administration twice daily.

Pharmacokinetic data (moderately high molecular weight, very high percentage of protein binding, high volume of distribution and low pKa) would explain the negligible excretion in breast milk observed in a single publication provided by the manufacturer. (AstraZeneca 2013)

Its low oral bioavailability, mostly when taken with food, hinder plasma passage from ingested milk by the infant except in preterm and immediate neonatal infants, who may have a greater intestinal absorption.

It has been used in infants from 12 months of age.

A drug of the same group and similar effect, the Montelukast, is excreted into breast milk in negligible amount.

Some authors consider the use of this medication to be probably safe during breastfeeding. (Nice 2004)

Until more data is available regarding breastfeeding, it may be preferable to choose alternatives that are known to be safer, especially in the neonatal period and/or in case of prematurity.

See below the information of this related product:


Suggestions made at e-lactancia are done by APILAM team of health professionals, and are based on updated scientific publications. It is not intended to replace the relationship you have with your doctor but to compound it. The pharmaceutical industry contraindicates breastfeeding, mistakenly and without scientific reasons, in most of the drug data sheets.

Jose Maria Paricio, Founder & President of APILAM/e-Lactancia

Your contribution is essential for this service to continue to exist. We need the generosity of people like you who believe in the benefits of breastfeeding.

Thank you for helping to protect and promote breastfeeding.

José María Paricio, founder of e-lactancia.

Other names

Zafirlukast in other languages or writings:


Zafirlukast belongs to this group or family:


Main tradenames from several countries containing Zafirlukast in its composition:


Variable Value Unit
Oral Bioavail. Baja - Poor %
Molecular weight 576 daltons
Protein Binding 99 %
VD 0.9 l/Kg
Tmax 2.5 - 3 hours
10 hours
M/P ratio 0.2 -
Theoretical Dose 0.0075 mg/Kg/d
Relative Dose 0.56 %


  1. Astrazeneca. Zafirlukast. Product Monograph. 2012 Full text (in our servers)
  2. AEMPS. Zafirlukast. Ficha técnica 2006 Full text (in our servers)
  3. Nice FJ, De Eugenio D, Dimino TA, Freeny IC, Rovnack MB, Gromelski JS. Medications and Breast-Feeding: A Guide for Pharmacists, Pharmacy Technicians, and Other Healthcare Professionals. Part I. J Pharm Technol 2004;20:17-27. doi: 10.1177/875512250402000106.

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e-lactancia is a resource recommended by Academy of Breastfeeding Medicine - 2015 of United States of America

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