What is the most appropriate contraceptive method for a woman taking 300 mg oxcarbazepine?

Best Contraceptive for 300 mg Oxcarbazepine

The copper IUD (Cu-IUD) or levonorgestrel IUD (LNG-IUD) are the best contraceptive options for a woman taking 300 mg oxcarbazepine, as both are highly effective and have no drug interactions with this anticonvulsant. 1

Why IUDs Are Optimal

• Both copper and levonorgestrel IUDs are classified as Category 1 (no restrictions) for use with oxcarbazepine, meaning there are no safety concerns or drug interactions 1
• Limited evidence confirms that anticonvulsants including oxcarbazepine do not interfere with the contraceptive effectiveness of the LNG-IUD 1
• The copper IUD provides highly effective contraception for 10-12 years with a failure rate of less than 1 per 100 women in the first year 2, 3
• The LNG-IUD is one of the most effective methods available with a Pearl index of 0.1 per 100 woman-years 4

Why Hormonal Contraceptives Are Problematic

Oxcarbazepine significantly reduces the effectiveness of combined hormonal contraceptives (pills, patches, rings) containing ethinylestradiol or levonorgestrel. 5

• The FDA drug label explicitly warns that oxcarbazepine decreases plasma concentrations of ethinylestradiol and levonorgestrel, which may result in contraceptive failure 5
• Women taking oxcarbazepine who use hormonal contraceptives containing these hormones must use additional or alternative non-hormonal birth control 5
• This interaction occurs even at the relatively low dose of 300 mg oxcarbazepine 1

Alternative Acceptable Options

If IUDs are not suitable or desired:

• Progestin-only methods (depot medroxyprogesterone acetate injections, etonogestrel implant, progestin-only pills) are acceptable alternatives as they do not have documented interactions with oxcarbazepine, though the guideline evidence is less explicit than for IUDs 1
• Barrier methods (condoms, diaphragm) can be used but have higher typical-use failure rates 1

Common Pitfalls to Avoid

• Do not prescribe combined oral contraceptives, patches, or vaginal rings without additional backup contraception, as oxcarbazepine will reduce their effectiveness 1, 5
• Do not assume that the low 300 mg dose of oxcarbazepine is insufficient to cause drug interactions—enzyme-inducing anticonvulsants affect hormonal contraceptives at therapeutic doses 1
• Counsel patients that if they choose hormonal contraceptives despite the interaction, they must use consistent backup methods 5

Clinical Implementation

• First-line recommendation: Offer copper IUD or LNG-IUD insertion 1
• Counsel that IUDs require no daily adherence and provide superior efficacy compared to user-dependent methods 2, 4
• If patient declines IUD, offer DMPA injection or etonogestrel implant as second-line options 1
• Provide counseling about the drug interaction if patient requests combined hormonal contraceptives, and document that additional barrier methods are required 5