If you agree to be in this study you will be admitted in to the General Clinical Research Center (GCRC) for approximately 24 hours on two different days (Part 1 and Part2). We will need you take a portion of your lamotrigine medication in a special form through a needle in your arm (intravenously). The special form of the drug is the same drug as you normally take except that it has a stable label (a NON-radioactive, naturally occurring atom) on the compound so that we can trace a small amount of the drug through your body. No commercial product of lamotrigine for intravenous use is available because of its poor solubility in water. The intravenous formulation used for this study has a chemical, hydroxypropyl-beta-cyclodextrin, that improves the solubility of lamotrigine in water. This formulation is similar to an intravenous formulation approved for another drug, Sporanox® (itraconazole) that is approved by the FDA. We have obtained approval form the FDA for this intravenous lamotrigine product to be used for research purposes and it has been shown to be safe in more than twenty younger individuals. We will collect fourteen (14) blood samples through a small tube placed into a vein in your arm and collect all of your urine over a period of 24 hours. One blood sample will then be drawn each day for 3 days for a total blood collection of seventeen (17 tubes (totaling approximately 170 mL or 11.5 tablespoons). The samples taken from you will be measured for blood chemistries and concentrations of lmaotrigine and its metabolites resulting from the medication that you take to control your disease (epilepsy or depression)