Is Singulair (montelukast) safe to use during pregnancy?

Montelukast (Singulair) Safety During Pregnancy

Montelukast (Singulair) can be safely used during pregnancy when the benefits outweigh the risks, particularly for women with recalcitrant asthma who have shown a favorable response prior to pregnancy. 1

FDA Pregnancy Classification and Safety Profile

Montelukast is classified as FDA Pregnancy Category B, which means:

• No teratogenicity was observed in animal studies at doses much higher than therapeutic human doses 2
• Animal reproduction studies have not demonstrated fetal risk 2
• There are no adequate and well-controlled studies in pregnant women 2

Evidence Supporting Safety in Pregnancy

• A multicentre, prospective comparative study of 180 montelukast-exposed pregnancies found that montelukast does not appear to increase the baseline rate of major malformations 3
• The European Respiratory Society (ERS) and Thoracic Society of Australia and New Zealand (TSANZ) task force statement indicates that montelukast can be considered "probably safe" during pregnancy 4
• Montelukast is considered appropriate for recalcitrant asthma during pregnancy, especially in women who have shown favorable response before pregnancy 1

Clinical Decision Algorithm for Montelukast Use in Pregnancy

1. First-line therapy consideration:

   • Inhaled corticosteroids (particularly budesonide) should be considered as first-line therapy before montelukast 1
   • For allergic rhinitis, intranasal corticosteroids may be preferred as first-line therapy 1

2. When to consider montelukast during pregnancy:

   • For women with recalcitrant asthma not adequately controlled with inhaled medications 1
   • For women who have shown favorable response to montelukast before pregnancy 1
   • As add-on therapy when inhaled corticosteroids alone are insufficient

3. Risk-benefit assessment:

   • The risk of undertreated asthma resulting in maternal hypoxia has well-documented adverse effects on the fetus 4
   • Benefits of controlling maternal asthma generally outweigh the potential risks of medication 4

Important Considerations and Monitoring

• During worldwide marketing experience, congenital limb defects have been rarely reported in offspring of women treated with montelukast during pregnancy 2
• Most of these women were also taking other asthma medications during pregnancy 2
• A causal relationship between these events and montelukast has not been established 2
• Merck maintains a pregnancy registry to monitor outcomes of women exposed to montelukast during pregnancy 2

Breastfeeding Considerations

• Studies in rats have shown that montelukast is excreted in milk 2
• It is unknown if montelukast is excreted in human milk 2
• Caution should be exercised when montelukast is given to nursing mothers 2
• Benefits of breastfeeding generally outweigh the risk of exposure 1
• Consider breastfeeding prior to medication intake to further limit exposure 1

Conclusion

When managing asthma during pregnancy, the risks of undertreated asthma must be weighed against potential medication risks. Montelukast has a favorable safety profile during pregnancy (Category B) and can be used when the benefits outweigh the potential risks, particularly in women with recalcitrant asthma who have shown good response before pregnancy.