12. Willing to have at least 21 blood samples collected during the pharmacokinetic testing including the in-facility session and outpatient portion for each period. The in-facility blood collections will mainly be performed using an inserted catheter. In the event of difficulty with the catheter or by subject preference, samples may be drawn by venipuncture. The outpatient portion consists of morning trough levels within +/-1 hour of the morning scheduled dose time on the 2 days prior to each research facility PK admission drawn by venipuncture for each of the 4 periods. The total amount of blood during each PK session will be equal to about 12 teaspoons (58.5 milliliters). The total amount of blood drawn throughout the entire study will be about 62 teaspoons (309.5 milliliters) or less. For reference, this amount is approximately two-thirds of the quantity of blood drawn during a standard blood donation by the Red Cross.