Azithromycin (Chlamydia / STI in Pregnancy)

DOSE SOURCE IS THE US LABEL. The UK SPC fetched in the bundle is Azithromycin 200 mg/5 mL powder for oral suspension, whose §4.2 extract covers ONLY paediatric patients aged 6 months and older weighing less than 45 kg (acute bacterial sinusitis, community-acquired pneumonia, skin and skin structure infections, acute otitis media, streptococcal tonsillitis/pharyngitis) — it carries no adult posology and no chlamydia/STI regimen, so the US prescribing information was used for the dose. OTHER US-LABELLED STI REGIMENS: gonococcal urethritis and cervicitis — one single 2 gram dose; genital ulcer disease (chancroid) — one single 1 gram dose. Azithromycin can be taken with or without food. This page's indication is treatment in pregnancy: the UK SPC §4.6 states there is a large amount of observational data (more than 7,000 exposed pregnancies) that mostly does not suggest an increased risk of major congenital or cardiovascular malformations, that epidemiological evidence on miscarriage risk in early pregnancy is inconclusive, and that azithromycin should only be used during pregnancy if clinically needed. Verify the regimen against the current national STI treatment guideline before use — the UK SPC advises that treatment should only be initiated after careful assessment of benefit and risk, considering local resistance prevalence, and when preferred treatment regimens are not indicated. PAEDIATRIC: per-kg regimens exist in both labels but ONLY for non-STI indications (otitis media 30 mg/kg single dose or 10 mg/kg daily for 3 days or 10 mg/kg day 1 then 5 mg/kg/day days 2–5; sinusitis and community-acquired pneumonia 10 mg/kg-based regimens; streptococcal pharyngitis/tonsillitis 12 mg/kg/day for 5 days or 20 mg/kg/day for 3 days). Those are NOT applicable to this page's STI indication, so paedDose is deliberately null; the paediatric daily dose must not exceed the adult daily dose of 500 mg except for the single-dose otitis media course (maximum total 1500 mg). Verify any paediatric use against a children's formulary. Ancillary sections below combine the UK SPC (contraindications, adverse reactions, pregnancy) with the US label (drug interactions, one additional contraindication) — the UK SPC §4.5 was not captured in the source bundle.