Use of amitriptyline in pregnancy

Amitriptyline is a tricyclic antidepressant (TCA) licensed for use in the management of depression, anxiety disorders and neuropathic pain. However, UK guidelines currently do not recommend the use of amitriptyline in the management of psychiatric disorders due to the risk of toxicity in overdose.

Although amitriptyline has been widely used in pregnancy, few studies have quantified pregnancy outcomes in women taking this medication. Whilst the currently available data do not raise concerns that amitriptyline is a teratogen, further studies are required for confirmation. Other adverse fetal effects following amitriptyline exposure have not been assessed.

There is no strong evidence of any association between TCAs, as a class of drugs, and congenital malformation overall, or of any specific malformations. Other findings are conflicting, with possible associations with spontaneous abortion, preterm delivery, and autism spectrum disorder identified in some (but not all) studies. While most of the studies of TCAs include (often a minority of) women exposed to amitriptyline, no separate assessment of their pregnancy outcomes was carried out and these data do not therefore provide information about specific amitriptyline exposure.

An increased incidence of neonatal complications has been reported in the offspring of women with psychiatric illnesses; however the relative contributions of the underlying maternal condition and specific drug treatments have not been clearly defined. While there are no specific data on amitriptyline exposure, use of TCAs throughout pregnancy or near delivery has been associated with withdrawal symptoms in the neonate and/or poor neonatal adaptation syndrome (PNAS). These symptoms are likely to be more severe in infants exposed in utero to more than one CNS acting drug.

No studies have assessed fetal/neonatal outcomes following amitriptyline overdose in pregnancy. However, overdose around the time of delivery, particularly overlaying chronic use, may increase the risk of neonatal withdrawal.

It is important to ensure that maternal chronic pain and/or mental health disorders are treated appropriately during pregnancy. Where a patient is stabilised on a TCA, either prior to conception or during pregnancy, the risk of discontinuing or changing medication, or reducing the dose, should be carefully weighed against the risk of relapse of the maternal condition.

The currently available data do not support the need for any additional fetal monitoring following in utero therapeutic exposure to TCAs; however, other risk factors may be present in individual cases which may independently increase the risk of adverse pregnancy outcome and the need for additional monitoring should therefore be determined on a case-by-case basis. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments.

Treatment of maternal amitriptyline overdose should be as for the non-pregnant patient and should not be withheld on account of the pregnancy.  For current guidelines regarding treatment of amitriptyline overdose please refer to TOXBASE®.