Various factors can affect the dissolution of a drug; they are classified under three categories as follows:
- Physiochemical properties of the drug
- Polymorphic form: A metastable form of a solid has higher solubility and dissolution compared to its stable counterpart.
- Particle size: The smaller the particle size of a solid, the larger the particle surface area and the higher the dissolution.
- 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.
- Hydrates versus anhydrates: The anhydrous form shows higher dissolution than hydrates due to their solubility differences.
- Factors related to tablet manufacturing
- The amount and type of binder can affect the hardness, disintegration, and dissolution of tablets.
- The method of granulation, granule size, and size distribution can affect tablet dissolution.
- The amount and type of disintegrants used, as well as the method of their addition, can affect disintegration and dissolution.
- Compression load can influence density, porosity, hardness, disintegration, and dissolution of tablets.
- Factors related to method of dissolution study
- Composition of the dissolution medium, pH, ionic strength, viscosity.
- Temperature of the medium.
- Intensity of agitation.
- Volume of dissolution medium.
- 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).
- Type of dissolution equipment.
- Sensitivity of analytical method used to determine drug concentration in the release medium.