THERAPEUTIC DRUG MONITORING OF AZATHIOPRINE AND TACROLIMUS IN SLE PREGNANCIES: PRELIMINARY RESULTS FROM THE LEGACY COHORT
Authors: Reem Farhat et al.
Pregnant SLE women face a high risk of maternal and fetal morbidity, particularly with active disease. Guidelines strongly recommend azathioprine (AZA) and tacrolimus (TAC). This study prospectively evaluated monitoring of AZA (erythrocyte-free 6-thioguanine, 6-TG) metabolites and TAC trough levels during 70 SLE pregnancies.
Among women prescribed AZA, only 9% had therapeutic levels. Among women prescribed TAC, 50% had therapeutic levels, 33% were subtherapeutic and 17% supra-therapeutic. 43% of pregnancies non-adherent to AZA were in Lupus Low Disease Activity State (LLDAS). Of the pregnancies with sub-therapeutic TAC levels, 50% were not in LLDAS, while all pregnancies with therapeutic or supra-therapeutic TAC levels were in LLDAS.
Drug monitoring detected large proportions of SLE patients with sub-therapeutic drug levels, and non-adherent patients. Drug monitoring may therefore be important to better control SLE activity in pregnant SLE women and reduce fetal risk.