- Repeated administration of the same dose of different drugs that have similar clearance will achieve the same drug s.s. conc.

- Repeated administration of the same dose of drugs with increasing f_m will result in a proportional increase in the metabolite formation rate

- Since the metabolite clearance is similar the increase in the metabolite formation rate will cause proportional increase in the s.s. metabolite conc and increase in the metabolite/drug concentration ratio at steady state.

The amount of the metabolite formed after drug administration depends on the dose of the drug and f_m. If f_m is equal to unity (1) for a particular metabolite, this means that the entire dose of the parent drug is converted to that metabolite.

Drugs that undergo parallel metabolism to more than one metabolite have different f_m values for each metabolite. The sum of these f_m values should not m m be more than one, but it does not have to be equal to one (when the drug elimination involves a pathway other than metabolism).

This fraction should be dose independent when drug elimination follows first-order kinetics. Also, this fraction should not be different for a particular drug in a particular patient after different routes of administrations, if the metabolite is not formed during drug absorption after extravascular administration.