People over 65 years of ag break down (metabolize) drugs differently than younger adults. It is not known why this happens or how elderly people absorb or break down these drug differently. These difference may show that elderly individuals need lower doses of medications to avoid possible toxicity. We are interested in studying how yor body absorbs and breaks down your lamotrigine medication. This research may indicate that doses of lamotrigine should be lowered as people get older.