Fig. 3.

Sildenafil apparent clearance versus body weight (a) and versus age (b) for the sildenafil reference model (gray) and based on between-drug extrapolation of clearance (black) with points representing the individual-predicted clearance by the reference model. In panel a, the lines represent population-predicted clearance values directly derived from the body weight–based covariate relationship, while in panel b, the lines represent the loess function summarizing the population-predicted clearance values with a 95% confidence interval (shaded area)