USE OF COLESTYRAMINE IN PREGNANCY

Colestyramine (cholestyramine) is an anion exchange resin that is not absorbed from the gastro-intestinal tract. Colestyramine forms an insoluble complex with bile acids in the intestine, preventing their reabsorption and resulting in a decrease in serum cholesterol and low-density lipoprotein concentrations. It is licensed for the treatment of diarrhoeal disorders, hypercholesterolaemia and pruritus associated with partial biliary obstruction and primary biliary cirrhosis. In pregnancy the drug has been used for relief from pruritus associated with intrahepatic cholestasis of pregnancy (ICP; also known as obstetric cholestasis), although current Royal College of Obstetricians and Gynaecologists (RCOG) guidelines state that colestyramine is ‘not in clinical use’ for this purpose. Colestyramine is also used in pregnancy as washout therapy for leflunomide and teriflunomide.

There are currently insufficient data to permit a meaningful risk assessment of the potential effects of colestyramine exposure in pregnancy and women should be made aware of this lack of information. However, because colestyramine is not absorbed systemically, it is not expected to have direct effects, although colestyramine may cause maternal deficiencies of fat-soluble vitamins which may lead to adverse fetal effects. In particular, maternal vitamin K deficiency (a recognised complication of ICP itself) may lead to hypoprothrombinaemia and thus bleeding disorders in the fetus and neonate. Assessment of maternal prothrombin time, appropriate maternal vitamin K supplementation and administration of vitamin K to the neonate, should be considered if treatment with colestyramine is needed in pregnancy. Current RCOG guidelines on the management of ICP recommend checking prothrombin time, even in the absence of colestyramine treatment.

Exposure to colestyramine at any stage in pregnancy would not be regarded as medical grounds for termination of pregnancy or any additional fetal monitoring. However, other risk factors which independently increase the risk of adverse pregnancy outcome may be present in individual cases. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments.