For CF patients with Pa, CAYSTON is the only inhaled antibiotic with a pregnancy category B classification.
No reproductive toxicology studies have been conducted with CAYSTON. However, studies were conducted with aztreonam for injection. Aztreonam has been shown to cross the placenta and enter fetal circulation. No evidence of embryo or fetotoxicity or teratogenicity has been shown in studies with pregnant rats and rabbits. In rats receiving aztreonam for injection during late gestation and lactation, no drug-induced changes in maternal, fetal, or neonatal parameters were observed.
No adequate and well-controlled studies of aztreonam for injection or CAYSTON have been conducted in pregnant women. Because animal reproduction studies are not always predictive of human response, CAYSTON should be used during pregnancy only if clearly needed.