Prescribing a leukotriene receptor antagonist
- The leukotriene receptor antagonists montelukast and zafirlukast are well tolerated and have few class-related adverse effects [GINA, 2006].
- Zafirlukast has been associated with liver toxicity. If clinical symptoms or signs suggestive of liver dysfunction occur (for example anorexia, nausea, vomiting, right upper quadrant pain, fatigue, lethargy, flu-like symptoms, enlarged liver, pruritus, or jaundice), stop zafirlukast and immediately measure serum transaminases (in particular, serum alanine aminotransferase). Routine monitoring of liver function is not recommended [ABPI Medicines Compendium, 2004].
- Use in children: montelukast is the only leukotriene receptor antagonist licensed for use in children (aged 6 months and older). A paediatric granule formulation is available, which can be swallowed or mixed with cold or room-temperature soft food and taken immediately [ABPI Medicines Compendium, 2007].
- Use in pregnancy: do not start a leukotriene receptor antagonist during pregnancy. However, if a woman is already taking a leukotriene receptor antagonist and it is considered essential, treatment can be continued during pregnancy [SIGN and BTS, 2011].
- In two small prospective studies no increase in the rates of congenital malformation, preterm birth, or low-birthweight was found. There have been several case reports of limb defects in women taking a leukotriene receptor antagonist during pregnancy, but a causal relationship has not been established [Schaefer et al, 2007].
Advice for patients
- Advise people taking zafirlukast to seek medical advice in the event of persistent nausea, vomiting, malaise, or jaundice [BNF 53, 2007].
- Advise the person that montelukast should not be used to relieve symptoms of an acute asthma exacerbation.