Metabolite Conc-Time Profile

The rate of change of the amount of the metabolite in the body after a single iv dose can be expressed as:

dA(m)

dt = A k - A(m) k(m)

Initially, the rate of metabolite formation is larger than the rate of metabolite elimination, so the amount of the metabolite in the body increases.

Parent drug

Metabolite

After some time, the rate of metabolite elimination becomes larger than the rate of metabolite formation and the amount of metabolite in the body decreases.

By integrating the above equation:

A(m) =

k D

k(m) - k (e-k t e-k(m) t)

The plasma metabolite concentration at any time after administration of a single iv dose of a drug is expressed as:

Cp(m) =

k D

Vd(m)( k(m) - k) (e-k t - e-k(m) t)
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