The metabolite formed after an iv administration of the parent drug can be further metabolized to a second metabolite. This second metabolite will be formed as a result of the elimination of the first metabolite.
Metabolite 2 formation rate is slow initially then it increases gradually until it reaches its maximum rate when metabolite 1 conc is at its maximum value.
Metabolite 2 conc-time profile can be described by a triexponential equation that includes drug elimination (also metabolite 1 formation), metabolite 1 elimination (also metabolite 2 formation), and metabolite 2 elimination.
