Centre for Eye Research Australia (CERA) - Research Publications
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ItemMaternal thiopurine metabolism during pregnancy in inflammatory bowel disease and clearance of thiopurine metabolites and outcomes in exposed neonates(WILEY, 2021-04)BACKGROUND: Azathioprine and mercaptopurine are considered safe during pregnancy. However, the pharmacokinetic effects of pregnancy on thiopurine metabolism are undefined. AIMS: To characterise thiopurine metabolism in pregnancy and measure infant metabolite levels and outcomes. METHODS: Women with IBD who were taking a thiopurine and pregnant or trying to conceive were recruited. Maternal thiopurine metabolites were measured pre-conception, in each trimester, at delivery and post-partum. Infant metabolite levels, full blood examination and liver function testing were performed at birth, and repeated until levels undetectable and haematological and biochemical abnormalities resolved. RESULTS: Forty patients were included with measurements on at least two occasions, and two with only mother-baby levels at delivery. The median maternal 6-TGN level dropped in the second trimester compared with post-partum (179.0 vs 323.5 pmol/8 × 108 RBCs, P < 0.001) and the median 6-MMP level increased in the second trimester compared with post-partum (1103.0 vs 329.5 pmol/8 × 108 RBCs, P < 0.01). At delivery, the median 6-TGN level was lower in infants (n = 20) than mothers (78.5 vs 217 pmol/8 × 108 RBCs) (P < 0.001). Metabolites were not detected at 6 weeks in any infants. Anaemia was not seen, but thrombocytosis and abnormal liver biochemistry were detected in 80% of infants from 6 weeks, which gradually improved. CONCLUSIONS: 6-TGN levels decrease and 6-MMP levels increase in the second trimester of pregnancy. Infants are exposed to thiopurine metabolites at low levels with clearance by 6 weeks and no anaemia. The cause of infant thrombocytosis and abnormal liver biochemistry in the absence of metabolites is unclear.
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ItemInfliximab, adalimumab and vedolizumab concentrations across pregnancy and vedolizumab concentrations in infants following intrauterine exposure(WILEY, 2020-11)Background The impact of pregnancy on levels of biologic agents in patients with IBD is undefined and time to elimination in vedolizumab‐exposed infants is unknown. Aims To determine the effect of pregnancy on infliximab, adalimumab and vedolizumab levels and to study infant vedolizumab clearance Methods In a prospective observational study, maternal drug levels were measured pre‐conception, in each trimester, at delivery and postpartum. The association between drug levels and gestation in weeks was assessed using generalised estimating equation modelling. Infant vedolizumab levels were performed at birth (cord blood), 6 weeks and 3 months or until undetectable. Results We included 50 IBD patients (23 on infliximab, 15 on adalimumab and 12 on vedolizumab) with at least two intrapartum observations, plus 5 patients on vedolizumab with only mother and baby samples at delivery. Modelling showed no change in adalimumab levels, an increase in infliximab levels of 0.16 (95% CI 0.08‐0.24) µg/L/week (P < 0.001) and a decrease of 0.18 (95% CI: −0.33 to −0.02) µg/L/week (P = 0.03) for vedolizumab. In 17 mother‐baby pairs, median infant vedolizumab levels at birth were lower than maternal levels (P < 0.05) with an infant:maternal ratio of 0.7 (IQR 0.5‐0.9). Vedolizumab was undetectable between 15 and 16 weeks of age in all 12 infants completing follow‐up testing. Conclusions During pregnancy, adalimumab levels remain stable, while infliximab levels increase and vedolizumab levels decrease. However, the increments were small suggesting that intrapartum therapeutic drug monitoring and dose adjustment are not indicated. Unlike infliximab and adalimumab, infant vedolizumab levels are lower in cord blood than in mothers and appear to clear rapidly.