drugs
Drug Action
Introduction
Drugs affect only the rate at which existing biologic functions proceed. (See also Definition of Drug Dynamics .) Drugs do not change the basic nature of these functions or create new functions. For example, drugs can speed up or slow down the biochemical reactions that cause muscles to contract, kidney cells to regulate the volume of water and salts retained or eliminated by the body, glands to secrete substances (such as mucus, stomach acid, or Drugs cannot restore structures or functions already damaged beyond repair by the body. This fundamental limitation of drug action underlies much of the current frustration in trying to treat tissue-destroying or degenerative diseases such as heart failure, arthritis, muscular dystrophy, multiple sclerosis, Parkinson disease, and Alzheimer disease. Nonetheless, some drugs can help the body repair itself. For example, by stopping an infection, antibiotics can allow the body to repair damage caused by the infection. Some drugs are hormones, such asinsulin, thyroid hormones,estrogens, orcortisol. They can be used to replace natural hormones that are missing from the body. 