Angiotensin receptor blockers (ARBs) and pregnancy and breastfeeding

ACE inhibitors and angiotensin II receptor antagonists (A2RAs) (angiotensin receptor blockers (ARBs)) use during breastfeeding

• ACE inhibitors and A2RAs (ARBs) should not be used at any stage of pregnancy, as exposure during pregnancy has been associated with adverse kidney effects and other congenital anomalies
  
  
• ACE inhibitors and A2RAs (ARBs) should not be used by breastfeeding mothers in the first few weeks after delivery because of possible profound neonatal hypotension; preterm babies may be at particular risk
  
  
• in mothers who are breastfeeding older infants, the use of captopril, enalapril, or quinapril may be considered, although careful follow-up of the infant for possible signs of hypotension is recommended (1)

A review by the NHS Specialist Pharmacy Service noted with respect to use of A2RAs (ARBs) during breastfeeding (2):

• there is almost no published evidence of the use of any medicine in this class during breastfeeding
• if there are no other therapeutic options, angiotensin-II receptor antagonists (ARBs) can be used with caution during breastfeeding
  • candesartan, losartan or valsartan have the most favourable pharmacokinetics and would therefore be preferred
    • however, given the very limited published evidence it would usually be preferable to choose a medicine from a different class which has more information supporting their use in breastfeeding
  • infants at most risk of side-effects
    • neonates and infants less than 2 months are at the most risk from the side-effects of angiotensin-II receptor antagonists, particularly hypotension, because they have underdeveloped clearance capacities, which means they can’t metabolise the medicines as effectively
    • in addition, there is theoretical concern that angiotensin-II receptor antagonists could affect kidney development. However, this has not been proven
    • if an angiotensin-II receptor antagonists is the best therapeutic option, extra caution should be taken when breastfeeding younger infants and neonates

Reference:

• 1. MeReC Monthly No.16 July 2009.
• NHS Specialist Pharmacy Service (May 2023). Using angiotensin-II receptor antagonists during breastfeeding