Cumulative remifentanil doses (in µg) to achieve and maintain a plasma concentration of 5 ng/ml over time when administered by target-controlled infusion for a 25-yr-old, 75-kg subject (solid line), a 75-yr-old, 75-kg subject (dotted line), and a 25-yr-old, 150-kg subject (dashed line) according to the final model. All subjects for these simulations are assumed to be 175 cm tall.