How long does it typically take for an atypical antipsychotic like olanzapine to reach steady state?

• A. 2 weeks
• B. 4 or more weeks
• C. 1 week
• D. 2 days

Answer: (C)

Steady state is reached when the amount of drug entering the body equals the amount leaving, so plasma levels stabilize. For olanzapine, the adult half-life is roughly 20–30 hours. A rule of thumb is that it takes about 4–5 half-lives to reach steady state, which translates to roughly 4–6 days. In clinical practice, this is typically described as about a week. So the best answer is about one week because it aligns with the usual time frame over which olanzapine accumulates to a steady plasma concentration. Variations can occur due to individual metabolism, liver function, age, or drug interactions, but a week is a reasonable general expectation.