A dose is usually repeated over a certain period. The plasma concentration in one or more patients during a certain period is depicted in a so called plasma concentration/time curve (Cp/time curve). Figure 11 shows the Cp/time curve of the first 7 days after starting treatment.

Figure 11: Cp/time curve

The shape of the Cp/time curves is defined by pharmacokinetic factors. The relationship between dose and plasma concentration is linear. This implies that if the dose is doubled, the steady state plasma concentration is also doubled (Figure 12).

Figure 12: Cp/time curve, dose doubled