Pharmacodynamics

Pharmacodynamics is the actions of drugs on the body.

For drugs to act upon the body the must be able to exert some chemical influence upon a cell to result in a physiological response. They are capable of doing this by binding to a target molecule (usually proteins).

There are four main kinds of targets for the drugs to bind to:

• Receptors - these are protein molecules that are capable of responding to endogenous chemical signals. They are usually found on the cell membrane, in the cytoplasm or on the nucleus and other organelles.
• Enzymes - both intracellular and extracellular ones.
• Ion Channels
• Transport proteins

Agonists

An agonist can be defined as a drug that binds to a target molecule and results in activation of the receptor and thus a tissue response.