Serious reaction reminders: sodium valproate and fetal malformations

Sodium valproate is well known to cause fetal malformations and is classified as a Pregnancy Category D drug (Drugs that have caused, are suspected to have caused or may be expected to cause an increased incidence of human fetal malformations or irreversible damage. These drugs may also have adverse pharmacological effects).¹ Teratogenic risk appears to be dose-dependent and increases markedly at doses greater than 1100 mg/day in the first trimester.²

Sodium valproate is mainly used to treat epilepsy but it is increasingly being prescribed to treat psychiatric disorders.

Since 1980, we have received 72 reports of babies born with malformations from mothers taking sodium valproate during pregnancy, including 18 of spina bifida, 4 of myelomeningocoele and 13 of multiple malformations mainly involving the CNS. In most of these cases, sodium valproate was being used to treat epilepsy, but two recent reports describe fetal spina bifida and myelomeningocoele in babies born to mothers taking sodium valproate for bipolar disorder.

One of the cases reported to us has been described in correspondence to the Australian and New Zealand Journal of Psychiatry³ and serves to remind all prescribers that sodium valproate must be used with caution after careful consideration of the risk-benefit profile in women of child-bearing potential.

Women of child-bearing age prescribed sodium valproate for any indication should be informed about the potential risks of the drug, including teratogenesis, and should be strongly advised, and periodically reminded, to maintain adequate contraception while taking this drug. Routine folic acid supplementation is recommended but efficacy in the prevention of sodium valproate-related malformation is unproven.⁴

All pregnant women taking sodium valproate should be encouraged to join The Australian Registry of Antiepileptic Drug Use in Pregnancy (ph 1800 069 722) to assist in monitoring the use of this drug in pregnancy.

References

1. ADEC. Prescribing medicines in pregnancy – An Australian categorisation of risk of drug use in pregnancy 4th edition (1999). Download this and updates from http://www.tga.gov.au/docs/html/medpreg.htm
2. Whitehall J & Smith J. Valproate and babies. Aust NZ J Psychiatry 2008; 42: 837.
3. Vajda FJ, O'Brien TJ, Hitchcock A, Graham J, Cook M, Lander C, Eadie MJ. Critical relationship between sodium valproate dose and human teratogenicity: results of the Australian register of anti-epileptic drugs in pregnancy. J Clin Neurosci 2004; 11: 854-83.
4. Lagrange AH. Folic acid supplementation for women with epilepsy who might become pregnant. Nature Clin Pract 2009; 5: 16-17.

Reference
Australian Adverse Drug Reactions Bulletin
Volume 28, Number 2, April 2009