PHARMACODYNAMICS IN DRUG INTERACTIONS

The study of the actions of drugs is called pharmacodynamics. Drugs can be
categorized as exerting an action in a general or a specific manner. Drugs with
general, nonspecific effects may affect all body tissues and cells. Drugs with specific
effects will have a target substrate that they act on, in one or more organ systems.
The fewer systems affected by the drug, the more specific its action. Specifically
acting drugs are generally considered better to work with from a pharmacodynamic
perspective. In contrast to the serendipitous manner in which drugs were developed
in the past, drug development now focuses on chemical specificity based on drug
and receptor structure. Drugs or foods that interfere directly with another drug’s
action would cause a drug–drug or drug–nutrient interaction. Drugs with an effect
similar to another drug may cause a greater than additive pharmacological effect.
This type of interaction is called synergism. Drugs with opposing pharmacological
effects may negate the benefits of one of the agents.