The full, clinically endorsed recommendation should be obtained from Lareb [link].   

Clinical overview  

Azithromycin is a macrolide antibiotic, used in pregnancy mainly for chlamydia trachomatis infections and as an alternative when penicillins are unsuitable. There is limited pharmacokinetic data available regarding azithromycin use in pregnancy. Researchers at Radboudumc conducted PBPK modelling simulations to create more evidence regarding azithromycin dosing in pregnancy. 

Pharmacokinetics of azithromycin in pregnancy 

Physiologically based modelling shows similar plasma concentrations between non-pregnant and pregnant individuals. This indicates that azithromycin exposure is not altered during pregnancy. The placental transfer of azithromycin appears to be variable, with placental perfusion experiments showing minimal transfer, while in vivo studies report neonatal levels that are approximately 50–80% of maternal levels 

Efficacy & safety of azithromycin in pregnancy 

Clinical experience suggests azithromycin remains effective in pregnancy. For the indications in which azithromycin is prescribed in the Netherlands, dose-related efficacy has not been studied in pregnancy. Overall safety data are reassuring, with most studies showing no increased risk of congenital malformations. However, dose-related safety has also not been demonstrated in pregnant patients.  

Conclusion  

Azithromycin pharmacokinetics appear unchanged in pregnancy. Overall safety data are reassuring, while evidence for dose-related efficacy and safety remains limited.