Overview of response to drugs

[Couch Potatoe]

Everyone responds to drugs differently. The way a person responds to a drug is affected by many factors, including

Genetic makeup
Age
Body size
Use of other drugs and dietary supplements (such as medicinal herbs)
Consumption of food (including beverages)
Presence of diseases (such as kidney or liver disease)
Storage of the drug (whether the drug was stored too long or in the wrong environment)
Development of tolerance and resistance

For example, a large person generally needs more of a drug than a smaller person needs for the same effect. Whether people take a drug as instructed (adherence) also affects their response to it. These factors may affect how the body absorbs the drug, how the body breaks down (metabolizes) and eliminates the drug, or what effects the drug has on the body.
Because so many factors affect drug response, doctors must choose a drug appropriate for each person and must adjust the dose carefully. This process is more complex if the person takes other drugs and has other diseases, because drug-drug and drug-disease interactions are possible.
A standard or average dose is determined for every new drug. But the concept of an average dose can be like