Final answer:
Combined oral contraceptives may decrease the plasma concentration of lamotrigine, potentially reducing its effectiveness in controlling seizures, which Samantha uses it for. It is crucial for individuals in this situation to consult with a healthcare professional to adjust doses or consider other contraceptive options.
Step-by-step explanation:
A student has inquired about the interaction between lamotrigine (Lamictal) and combined oral contraceptives (COCs). Samantha, who is taking lamotrigine for her seizures, wants to use COCs, which may cause an interaction that leads to a decrease in the plasma concentration of lamotrigine. This reduction can potentially diminish the efficacy of lamotrigine and lead to an increased risk of seizure activity. It's essential for patients taking lamotrigine who request COCs to discuss these potential interactions with their healthcare provider to evaluate the need for adjusting the lamotrigine dose or considering alternative contraceptive methods.