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The precautions about use of phenytoin, phenobarbital, primidone and zonisamide during pregnancy and in women of childbearing potential have been updated to raise awareness of essential preconception care, bringing the Product Information (PI) in line with other antiepileptic medicines.
When prescribing antiepileptic medicines, it is essential to counsel women of childbearing potential about the need for effective contraception and preconception reassessment. Prescribers should provide this advice before the patient starts treatment with antiepileptic medicines and regularly during treatment.
To guide prescribers, the PI for phenytoin, phenobarbital, primidone and zonisamide now includes the latest advice on the safe use of these medicines in women of childbearing potential.
Please follow this advice before and when prescribing antiepileptic medicines:
- Do not prescribe these medicines for pregnant patients unless it is clearly necessary. The potential benefit must justify the risk to the developing fetus after careful consideration of alternative treatment options.
- Before prescribing, provide advice to women of childbearing potential about the risks involved during pregnancy and the possible effects of antiepileptic medicines on a developing fetus.
- Women of childbearing potential should use effective contraception during treatment with antiepileptic medicine and for one month after stopping it. Ensure the contraceptive they are using is adequate and appropriate for their situation.
- Inform women taking antiepileptic medicines that their treatment should be reassessed when they are planning a pregnancy.
Consult the PI of the medicine you are prescribing for specific advice and warnings.
Background information
The Therapeutic Goods Administration (TGA) evaluated the safety data for use of epilepsy medicines during pregnancy in Australia following a similar review in the United Kingdom [1]. After reviewing the TGA's evaluation report, the Advisory Committee on Medicines (ACM) recommended a safety update to the Australian PI for phenobarbital, phenytoin, primidone and zonisamide to better communicate the risks of their use in pregnancy and in women of childbearing potential [2].
The ACM noted that these antiepileptic medicines may also be approved or used for conditions other than epilepsy, such as migraine, bipolar disorder, trigeminal neuralgia, anxiety and neuropathic pain.
The TGA review found that the PIs for the antiepileptic medicines carbamazepine, lamotrigine, levetiracetam, topiramate, gabapentin, pregabalin and clobazam adequately describe the risks in pregnancy and did not require updating.
Post-marketing adverse event data
To 6 May 2022, there were a total of 421 reports for congenital and pregnancy related adverse events for anticonvulsants in the TGA's Database of Adverse Event Notifications, as follows: carbamazepine 140, levetiracetam 74, lamotrigine 63, topiramate 56, phenytoin 50, primidone 13, pregabalin 7, oxcarbazepine 5, clobazam 5, phenobarbital 4, gabapentin 3, zonisamide 1.
Reference
| [1] | Medicines and Healthcare products Regulatory Agency. Antiepileptic drugs: review of safety of use in pregnancy. 2021. |
|---|---|
| [2] | Therapeutic Goods Administration. Advisory Committee on Medicines meeting statement. 2021. |
What to report? You don't need to be certain, just suspicious!
The TGA encourages the reporting of all suspected adverse reactions to medicines, including vaccines, over-the-counter medicines, herbal, traditional or alternative remedies.
We particularly request reports of:
- all suspected reactions to new medicines (look for the Black Triangle in PI and CMI documents - this symbol identifies medicines that are new or being used differently)
- all suspected medicines interactions
- suspected reactions causing death, admission to hospital or prolongation of hospitalisation, increased investigations or treatment, or birth defects.
Reports may be submitted:
- online at www.tga.gov.au
- by fax to 02 6232 8392
- by email to ADR.Reports@tga.gov.au
For more information about reporting, visit www.tga.gov.au or contact the TGA's Pharmacovigilance and Special Access Branch ADR.Reports@tga.gov.au.
Disclaimer
Medicines Safety Update is aimed at health professionals. It is intended to provide practical information to health professionals on medicine safety, including emerging safety issues. The information in Medicines Safety Update is necessarily general and is not intended to be a substitute for a health professional's judgment in each case, taking into account the individual circumstances of their patients. Reasonable care has been taken to ensure that the information is accurate and complete at the time of publication. The Australian Government gives no warranty that the information in this document is accurate or complete, and shall not be liable for any loss whatsoever due to negligence or otherwise arising from the use of or reliance on this document.
© Commonwealth of Australia 2022
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For correspondence or further information about Medicines Safety Update, contact the TGA's Pharmacovigilance and Special Access Branch at ADR.Reports@tga.gov.au.
Medicines Safety Update is written by staff from the Pharmacovigilance Branch.
Editor: Ms Elspeth Kay
Deputy Editor: Mr Michael Pittman
Contributors: Ms Prajakta Narvekar, Ms Jovi van der Kallen