Which pharmacokinetic process primarily occurs in the intestines?

Absorption is the pharmacokinetic process that primarily occurs in the intestines. This process involves the transfer of a drug from the site of administration into the bloodstream. In the case of oral medications, the drug first enters the gastrointestinal tract, where it is dissolved and absorbed through the intestinal mucosa into the systemic circulation. The intestines have a large surface area due to the presence of villi and microvilli, which enhances the capability for drug absorption significantly.

The other processes, while related to pharmacokinetics, occur in different contexts. Metabolism typically takes place in the liver, where drugs undergo chemical transformation, often resulting in their conversion to more water-soluble compounds that can be excreted. Excretion mainly occurs through the kidneys, where waste products and non-reabsorbed drugs are eliminated from the body. Distribution refers to how the drug disperses throughout the body's tissues and fluids after it enters the bloodstream, which is influenced by factors such as blood flow and the drug's affinity for different tissues.