Porosity is a characteristic that influences many of the critical quality attributes of finished pharmaceutical products. Porosity can help predict deformation properties during compression, pharmacokinetic behavior within the body, shelf life, moisture penetration, and bioavailability. In theory, porosity measurements could also be a predictor for dissolution rates. The more porous a product, the more water or gastric fluid should be able to infiltrate the tablet and dissolve the tablet, allowing the active pharmaceutical ingredient (API) to be released. Dissolution rate is a key attribute for immediate-release drugs, so understanding how the porosity of each substance affects the final dissolution rate is of great importance in creating an immediate-release drug formulation. Porosity and surface area of a substance can be measured by gas adsorption analysis usually by the Brunauer, Emmett and Teller (BET) technique or by mercury intrusion porosimetry.