Lamotrigine interactions with oral contraceptives

M s. A, age 20, presents to the clinic after experiencing difficulty sleeping, depressed mood, fatigue, and difficulty concentrating. Her psychiatric history includes bipolar II disorder (BD II), predominantly with depressive episodes. Ms. A’s current medications include a combination of lamotrigine 200 mg/d and bupropion extended-release 450 mg/d, and her symptoms were well maintained until 2 weeks ago. When her psychiatrist performs a medication reconciliation at her medication management appointment, Ms. A indicates she started taking an oral contraceptive, ethinyl estradiol and norgestimate, approximately 1 month ago for management of endometriosis symptoms. She is not currently taking any other medications or supplements.