Definition of Drug
A drug may be defined as any substance that brings about a change in biologic function through its chemical actions. It can also be said to mean any substance (other than food that provides nutritional support) that, when inhaled, injected, smoked, consumed, absorbed via a patch on the skin, or dissolved under the tongue causes a temporary physiological (and often psychological) change in the body.
In the great majority of cases, the drug molecule interacts with a specific molecule in the biologic system that plays a regulatory role. This molecule is called a receptor.
Antagonistic Drugs
Drugs known as chemical antagonists may interact directly with other drugs, whereas a few drugs (osmotic agents) interact almost exclusively with water molecules.
Xenobiotics and Hormones
Drugs may be synthesized within the body (e.g, hormones) or may be chemicals not synthesized in the body, ie, xenobiotics.
Poisons as drugs
Poisons are drugs that have almost exclusively harmful effects. Toxins are usually defined as poisons of biologic origin, i.e, synthesized by plants or animals, in contrast to inorganic poisons such as lead and arsenic.
Pharmacological Drugs
In pharmacology, a drug is a chemical substance of known structure, other than a nutrient of an essential dietary ingredient, which, when administered to a living organism, produces a biological effect.
Pharmaceutical Drugs
A pharmaceutical drug, also called a medication or medicine, is a chemical substance used to treat, cure, prevent, or diagnose a disease or to promote well-being. Pharmaceutical drugs may be used for a limited duration, or on a regular basis for chronic disorders.
Traditional Drugs
Traditionally drugs were obtained through extraction from medicinal plants, but more recently also by organic synthesis.
References
- Drug. Wikipedia. Accessed August 8, 2021
- Overview of Drugs. Merck Manual. Accessed August 8, 2021