Excretion Parameters

Excretion Parameters

Figure 1 below shows the excretion parameters of Aspirin

Total Clearance (CL)

• Importance: Measures the rate at which a drug is removed from the body (by all routes, including metabolism and excretion). It determines the drug's dosing rate.

• Desirable Range: The units are typically log(ml/min/kg). A balanced clearance is desired—not too fast (requiring frequent dosing) and not too slow (leading to accumulation).

•  Aspirin has a low clearance rate.

Half-life (t½)

• Definition: Time required for plasma concentration to decrease by half.

• Importance: Determines dosing frequency. Longer half-lives allow less frequent dosing. Aspirin itself has a short half-life of 0.822 (Figure 1).