3.1 : Drug Administration and Therapy Phases: Overview

Drugs, the chemical agents used in diagnosing, treating, or preventing diseases, undergo a four-phase process of development: pharmaceutic, pharmacokinetics, pharmacodynamics, and therapeutic.

The pharmaceutical phase focuses on leveraging the physicochemical properties of the drug to design and manufacture an effective product. Variants include orally administered tablets or capsules, topical creams or ointments, and parenteral-delivery solutions or emulsions.

The pharmacokinetic phase follows, detailing how the body absorbs, distributes, metabolizes, and excretes the drug post-administration. This phase provides valuable insights into the physiological processing of drugs.

In the pharmacodynamic phase, the focus shifts to the drug's interaction with its target, which could be receptors, ion channels, enzymes, or transporters. This phase elucidates the relationship between drug concentration and its effect, shedding light on potential therapeutic or toxic impacts.

The final therapeutic phase translates these pharmacological effects into clinical outcomes. It assesses how the drug's interaction with the target—either by inhibiting or activating it—can alleviate disease symptoms. As a result, this comprehensive four-phase process ensures the development of efficacious and safe drugs.