Mean Dissolution Time (MDT) is defined as which of the following?

• A. MDT is the maximum time to dissolve the entire dose.
• B. MDT measures the time to reach 100% dissolution.
• C. MDT is the average time required for the drug to dissolve from the dosage form; lower MDT indicates faster dissolution and often better bioavailability; calculated from dissolution data.
• D. MDT is a measure of tablet hardness.

Answer: (C)

MDT is the average time it takes for the drug to dissolve from the dosage form, reflecting the overall dissolution behavior rather than a single endpoint. It’s essentially a weighted average (the first moment) of the dissolution profile: each interval’s time is weighted by the amount dissolved in that interval. Because it combines both how fast the drug releases and how much ultimately dissolves, a formulation that dissolves quickly will have a smaller MDT, often linking to better bioavailability, while a slower or prolonged dissolution raises MDT. It’s computed from dissolution data, not from an endpoint like 100% dissolution, and it has nothing to do with tablet hardness.