The determination of dissolution rate is an essential part of quality control. Dissolution testing aims to determine the rate at which an active pharmaceutical ingredient (API) is released from its formulation under standardized conditions. In practice, the quantity of drug dissolved in the dissolution medium at time X after addition of the FDF or API is determined. The amount of time required to dissolve the desired amount of API can vary significantly depending on the product being tested. In the case of immediate release dosage forms, the test is usually carried out at a single point in time (usually 45 minutes or less). Multiple samples are collected in the case of extended or delayed release.