Derelict is right.
The terminal elimination half-life of dutasteride is approximately 5 weeks at steady state.
The average steady-state serum dutasteride concentration was 40 ng/mL following 0.5 mg/day for
1 year. Following daily dosing, dutasteride serum concentrations achieve 65% of steady-state
concentration after 1 month and approximately 90% after 3 months.
Due to the long half-life of dutasteride, serum concentrations remain detectable (greater than 0.1 ng/mL) for up to 4 to
6 months after discontinuation of treatment.