A drug is any substance that causes a change in an organism’s physiology or psychology when consumed.
In pharmacology, a drug is a chemical substance, typically of known structure, which, when administered to a living organism, produces a biological effect.
Pharmaceutical drugs are often classified into drug classesgroups of related drugs that have similar chemical structures, the same mechanism of action , a related mode of action, and that are used to treat the same disease. The Anatomical Therapeutic Chemical Classification System , the most widely used drug classification system, assigns drugs a unique ATC code, which is an alphanumeric code that assigns it to specific drug classes within the ATC system.
Psychoactive drugs are chemical substances that affect the function of the central nervous system, altering perception, mood or consciousness. These drugs are divided into different groups like: stimulants, depressants, antidepressants, anxiolytics, antipsychotics, and hallucinogens.
The most widely used drugs in the world include caffeine, nicotine and alcohol, Excessive use of stimulants can promote stimulant psychosis.Many recreational drugs are illicit and international treaties such as the Single Convention on Narcotic Drugs exist for the purpose of their prohibition.
