Sulfadiazine plasma concentrations in women with pregnancy-acquired compared to ocular toxoplasmosis under pyrimethamine and sulfadiazine therapy: a case-control study.

SA plasma concentrations were found in the median 34% lower in pregnant women with PT compared to OT patients and fell below a lower reference value of 50 mg/l in a substantial portion of PT patients. The interindividual variability of plasma concentrations in combination with systematically lower drug levels and possibly a lower compliance in pregnant women may thus account for a still not yet supportable transmission risk. Systematic drug-level testing in PT under PY/SA treatment deserves to be considered.