
152 Computational Pharmacokinetics
FIGURE 6.7: Cortisol levels over 24 hours
Typical plasma cortisol levels and variability are illustrated in Figure 6.7,
which contains cortisol data over a 24 hour period from the study discussed
in Section 3.6. These data were obtained on drug free day, showing the pro-
nounced diurnal variation that cortisol levels in plasma exhibit, being at their
lowest in the late evening and around midnight and peaking in the early
morning.
To apply the turnover model to this, let E(t)=C(t). Assuming that equa-
tion 6.9 holds, we can estimate the production rate k
in
(t) by first numerically
differentiating C(t) and then using that, ...