Various factors can affect the dissolution of a drug; they are classified under three categories as follows:

1. Physiochemical properties of the drug
   1. Polymorphic form: A metastable form of a solid has higher solubility and dissolution compared to its stable counterpart.
   2. Particle size: The smaller the particle size of a solid, the larger the particle surface area and the higher the dissolution.
   3. Salt form: A salt form of a drug has a higher aqueous solubility compared to its conjugate acid or base, as well as higher dissolution.
   4. Hydrates versus anhydrates: The anhydrous form shows higher dissolution than hydrates due to their solubility differences.
2. Factors related to tablet manufacturing
   1. The amount and type of binder can affect the hardness, disintegration, and dissolution of tablets.
   2. The method of granulation, granule size, and size distribution can affect tablet dissolution.
   3. The amount and type of disintegrants used, as well as the method of their addition, can affect disintegration and dissolution.
   4. Compression load can influence density, porosity, hardness, disintegration, and dissolution of tablets.
3. Factors related to method of dissolution study
   1. Composition of the dissolution medium, pH, ionic strength, viscosity.
   2. Temperature of the medium.
   3. Intensity of agitation.
   4. Volume of dissolution medium.
   5. Sink or nonsink conditions (under a sink condition, the concentration of the drug should not exceed 10%15% of its maximum solubility in the dissolution medium in use).
   6. Type of dissolution equipment.
   7. Sensitivity of analytical method used to determine drug concentration in the release medium.