Which statement about particle size distribution and dissolution is correct?

• A. Uniformly large particles always improve dissolution.
• B. Smaller, uniform particles increase surface area and dissolution rate, enhancing bioavailability; broad size distribution can cause inconsistent dissolution and absorption.
• C. Particle size distribution has no impact on dissolution.
• D. A broad distribution guarantees consistent release.

Answer: (B)

The main concept here is that dissolution rate is driven by surface area available for dissolution. When you have smaller particles, the total surface area per unit mass increases, so more surface is in contact with the dissolution medium at the same time. This speeds up the dissolution process and can improve bioavailability if dissolution is the rate-limiting step. Keeping the particle sizes uniform (a narrow particle size distribution) makes this dissolution behavior more predictable across the dose, reducing variability in absorption.

If the distribution is broad, you’ll have a mix of very small and very large particles. The small ones dissolve quickly, while the large ones dissolve slowly, leading to an inconsistent overall dissolution profile and variable absorption between doses or patients. That’s why the statement emphasizing smaller, uniform particles increasing surface area and dissolution rate—and broad distributions causing inconsistency in dissolution and absorption—best captures the relationship.

The other ideas don’t fit because larger particles have less surface area and dissolve more slowly, particle size distribution does affect dissolution, and a broad distribution does not guarantee consistent release.