IVIVC Level B correlation versus Level A correlation: which statement correctly differentiates their relationship to in vivo data?

• A. Level B yields a direct point-to-point plasma concentration-time correlation.
• B. Level A provides the direct, quantitative point-to-point correlation between dissolution and the plasma concentration-time profile, offering higher predictability.
• C. Level B provides the most direct in vivo plasma concentration correlation.
• D. Level A is more predictive than Level B.

Answer: (C)

IVIVC levels describe how well in vitro dissolution predicts the in vivo plasma profile over time. The strongest, most predictive link is Level A, which gives a direct point-to-point correlation between the in vitro dissolution and the in vivo plasma concentration–time profile. Because each time point in vitro maps to the corresponding time point in vivo, you can predict the entire in vivo curve from the dissolution data with high accuracy.

Level B, on the other hand, links the overall in vitro dissolution profile to an in vivo parameter or to a transformed view of the in vivo data (such as a mean residence time or AUC), rather than matching time points directly. This makes Level B less direct and typically less predictive of the full plasma concentration–time profile than Level A.

Thus, the statement describing Level A as the direct, point-to-point correlation with higher predictability is the correct differentiation.