USE OF ACETAZOLAMIDE IN PREGNANCY

Acetazolamide is a carbonic anhydrase inhibitor indicated in the treatment of glaucoma, abnormal retention of fluid, and epilepsy. Unlicensed indications also include altitude sickness prophylaxis and the management of idiopathic intracranial hypertension.

Animal studies have identified increased risks of limb and axial skeletal anomalies following administration of very high doses of acetazolamide to rodents and rabbits but not rhesus monkeys. The available human exposure data consist mainly of case reports/series and a small number of cohort studies which detail the outcomes of more than 1,000 acetazolamide-exposed pregnancies; however, only 85 of these pregnancies were exposed in the first trimester. The congenital malformation data are therefore highly limited, and although there is no signal that acetazolamide is a major human teratogen, the data are too limited to exclude a more subtle effect on the developing fetus. When pregnancy is being considered, any theoretical risks to the fetus should be weighed against the potential adverse effects of not treating the maternal condition.

Data concerning the risk of miscarriage, low birth weight, preterm delivery and neurodevelopmental impairment are both limited and confounded. Additional controlled studies are required before reliable conclusions regarding the risk of these outcomes can be provided.

A number of neonatal complications, including dehydration, lethargy, breathing difficulties, metabolic acidosis, hypoglycaemia, hyperbilirubinaemia, hypocalcaemia, hypomagnesaemia and neonatal death have been described in exposed infants. However, the contribution of the underlying maternal illness, concomitant exposures and other clinical risk factors to these events is currently unclear. Nonetheless, metabolic acidosis is a recognised effect of acetazolamide treatment and as case reports have described acidosis in neonates following exposure in later pregnancy, neonatal monitoring may be advised where use has occurred in the weeks before delivery.

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