Which antipsychotic has bioavailability greater than 99%?

• A. Brexpiprazole
• B. Haloperidol
• C. Fluphenazine
• D. Olanzapine

Answer: (A)

Understanding how an oral dose becomes available in the bloodstream is key. Bioavailability is the fraction of an oral dose that reaches systemic circulation. When that value is essentially 100%, almost every milligram you take ends up in the bloodstream, giving you predictable and consistent drug exposure.

Brexpiprazole stands out because its oral bioavailability is essentially complete, approaching or exceeding 99%. That means the oral dose is absorbed with minimal loss to first-pass metabolism, leading to very reliable plasma levels across patients. This makes dosing more predictable compared with other antipsychotics in the list, which experience more substantial first-pass effects or absorption variability.

In contrast, the other medications listed have lower or more variable oral bioavailability due to first-pass metabolism and other absorption factors, so they don’t achieve the same near-total systemic exposure from an oral dose.