- Repeated administration of the same dose of different drugs will achieve the same average steady state conc if the clearance is similar. In this case the metabolite formation rate at steady state will be similar if f_m is the same.

- When the formation rate of the metabolite and the metabolite clearance are similar, the s.s. metabolite conc will be the same. So, the drug to metabolite conc ratio will be the same at steady state.

- Drugs with larger Vd have longer half life if the clearance is the same. Notice the slower rate of approaching the steady state for the drugs with larger Vd.

The volume of distribution is the apparent volume in which the drug can be distributed in. It is the factor that relates the amount of drug in the body to the concentration of the drug in the sampling site. It is not an actual volume, however it is a hypothetical volume determined by the drug distribution behavior.

The volume of distribution ranges from 3-5 liters to more than 25 L/kg. Drugs with higher affinity for tissues, have higher volume of distribution.