Quetiapine XR requires how long to re-establish steady-state after a dose change?

• A. 2 weeks
• B. 1 month
• C. 3 months
• D. 6 months

Answer: (C)

Steady-state after a dose change depends on how long the drug stays in the body, which is tied to the drug’s half-life. Quetiapine XR, while formulated for once-daily dosing, does not have an extremely long half-life; the parent drug has roughly a 6–7 hour half-life and the active metabolite Norquetiapine is in a similar range. Because steady-state typically requires about 4–5 half-lives to accumulate to a consistent level, re-establishment after a dose change is usually achieved within a few days, with full clinical stabilization often within about a week and sometimes up to 1–2 weeks.

The options listed imply much longer times (weeks to months), which is not in line with standard pharmacokinetics for quetiapine XR. If you’re choosing the option that best fits typical practice, two weeks would be the most reasonable estimate among those choices. If a source states months, that would be unusual for this drug and likely reflects a special context outside ordinary PK for quetiapine XR.