MDT provides a concise summary measure of dissolution performance; which statement best reflects this concept?

• A. MDT is a measure of dissolution variability across dosage units.
• B. MDT is the time to complete dissolution for 50% of the drug.
• 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 the time to reach peak plasma concentration.

Answer: (C)

Mean dissolution time is a single summary metric of dissolution performance, representing the average time required for a dosage form to dissolve, based on the dissolution profile data. It is calculated from the dissolution data by weighting time by the amount dissolved up to each point, so it reflects the entire dissolution process rather than a single time point. A lower MDT indicates faster dissolution, which often correlates with better bioavailability because dissolution is frequently the rate-limiting step for many drugs. This measure captures how quickly the drug leaves the dosage form across the whole profile, rather than focusing on the time to complete dissolution of a fixed fraction (which can be misleading) or on variability between units. It is not the time to reach peak plasma concentration, which is determined by pharmacokinetics after dissolution and absorption.