Psychoactive drugs are commonly grouped into categories based on administrative control, psychoactive effects, and source of drug/method of manufacture. According to these classification systems, ATS are classified as psychotropic synthetic stimulants. This section describes three classification systems: legal, psychoactive effects, and source/method of manufacture. This section also highlights the problem of reliability.

Legal Classification of Drugs
A legal classification system has been devised for by two U.N. Conventions, creating three main classifications of drugs:

• Narcotic drugs
• Psychotropic substances
• Controlled substances

Narcotic drugs
Narcotic drugs are internationally defined as chemical substances under control of the United Nations Single Convention on Narcotic Drugs (1961). All of them are called “narcotic drugs”, although some of them, such as cannabis or cocaine, do not produce “narcotic” effects such as stupor or sleep. The concept “narcotic drugs” is thus a term of international law describing drugs under special control, not necessarily their primary mind-altering effects.

Under the convention, more than a hundred substances are classified as narcotic drugs and include cannabis and cannabis resin; opium, morphine, heroin and a number of other natural and synthetic opiates; coca leaves and cocaine. All drugs internationally scheduled as narcotic drugs must be domestically controlled by governments who have ratified the Single Convention, i.e. most nations in the world. Please see International Framework for more information.

Psychotropic substances
In the context of international drug control, ‘psychotropic substances’ refers to a substance controlled by the 1971 Convention of Psychotropic Substances. According to the WHO Lexicon of Alcohol and Drug Terms, psychotropic is in its most general sense a term with the same meaning as ‘psychoactive’, i.e., affecting the mind or mental processes.

Psychotropic substances include: amphetamine, phenmentrazine and similar synthetic CNS stimulants; barbiturates; benzodiazepines; ecstasy, LSD and other synthetic hallucinogens; psilocybine and other natural hallucinogens; chloral hydrate and many other substances. Please see International Framework for more information.

Controlled substances
“Controlled substances” or “controlled drugs” are often used as judicial labels for all drugs under special control in a particular country. This group may encompass e.g narcotic drugs, psychotropic substances, precursors, doping agents and additional drugs under national control. At both national and international levels, controlled substances and precursors are commonly classified according to a hierarchy of schedules, reflecting different degrees of restriction and availability through medical and pharmaceutical channels.

Psychoactive Effects
Drugs can be classified by the psychoactive effects they induce. Psychoactive substances fall into three main groups:

• Depressants
• Stimulants
• Hallucinogens

Depressants
Depressants are agents that suppress, inhibit, or decrease central nervous system (CNS) activity. The CNS is one of the two major divisions of the nervous system and is comprised of the brain and the spinal cord. The main CNS depressants are sedatives/hypnotics, opioids, and neuroleptics. These drugs make people more relaxed and less conscious of their surroundings. Some of their medical uses include sedation, sleep induction, hypnosis, and general anaesthesia. Examples of depressant drugs include alcohol, anaesthetics, sleeping pills, and opioid drugs such as heroin, morphine, and methadone.

Sought-after effects
• Relief of tension, mental stress and anxiety
• Warmth, contentment, relaxed detachment from emotional as well as physical distress
• Positive feelings of calmness, relaxation and well being in anxious individuals
• Relief from pain

These drugs include opioids, solvents and inhalants, sedatives and tranquilizers.

Stimulants
Stimulants are agents that activate, enhance, or increase neural activity in the CNS (also called psychostimulants). These drugs have numerous physiological effects such as altering heart rate, dilating pupils, elevating blood pressure, increasing perspiration, and causing nausea and vomiting. They may also induce alertness, agitation, and impaired judgement. Chronic misuse commonly induces personality and behaviour changes such as impulsivity, agressivity irritability, and suspiciousness. Amphetamines, cocaine, caffeine, nicotine, and synthetic appetite suppressants fall into this group. Other drugs may have stimulant actions, which are not their primary effect, if they are taken in high does or after chronic use.

Sought-after effects
• feelings of physical and mental well being, exhilaration, euphoria, elevation of mood
• increased alertness, energy and motor activity
• postponement of hunger and fatigue

Hallucinogens (psychedelics)
Hallucinogens are chemical agents that alter our perceptions, thinking, feelings, and sense of time and place. They induce delusions, hallucinations, and paranoia. In addition to hallucinations, adverse effects are frequent and include unpleasant and frightening hallucinatory experiences (“bad trips”), post-hallucinogen perception disorder or flashbacks, delusional disorder – the perception that the hallucination was real after the perceptual changes abate, and mood disorder (anxiety, depression, or mania).

Sought-after effects
• alterations in mood, feeling and thought, “mind expansion”
• enhancement of sensory experiences; more vivid sense of sight, smell, taste and hearing
• dissociation of body and mind]

Hallucinogenic drugs include mescaline (the hallucinogenic substance of the peyote cactus), ketamine, LSD, and psilocybin (the hallucinogenic substance of the psilocybe mushroom), phencyclidine (PCP), some hallucinogenic amphetamines, and even marijuana and hashish.

Source of Drug / Method of Manufacture
Drugs are often classified by the source of the drug as well as the method by which it is manufactur-ed. This classification method includes three main groups:

• Natural (plant-based) drugs
• Semi-synthetic drugs
• Synthetic drugs

Broadly speaking, there are two major classifications of drugs, ‘synthetic drugs’ and ‘plant-based’ (also ‘botanical’ or ‘natural’) drugs. Although the term ‘synthetic drug’ is nowadays frequently equated with ‘ecstasy’ or ‘amphetamine-type stimulant’, it covers a much broader spectrum of man-made substances. The distinctive feature of synthetic drugs, as opposed to plant-based drugs is that they are synthesized in a chemical laboratory, usually from ‘off-the-shelf’ chemicals (so-called precursors or starting materials). Plant-based drugs, by contrast, are obtained by refining or processing plant material.

Natural (plant-based) drugs
Cannabis, opium, and coca products are examples of natural drugs that can be consumed in their natural form to produce a psychoactive effect. The psychoactive ingredients of plant-based drugs may be extracted and concentrated to intensify the effects or to facilitate ingestion, but the psychoactive ingredients are not chemically altered. Natural drugs are generally chewed, eaten, drunk, or smoked.

Examples of plant-based drugs are cocaine and morphine, the active principles in coca leaf and opium poppy, respectively. Heroin is sometimes also considered plant-based, although it is produced by minor chemical modifications of morphine, and should therefore be more accurately classified a ‘semi-synthetic’ drug. The group of synthetic drugs comprises, for example, the stimulants amphetamine and methamphetamine, ecstasy, the depressant drugs methaqualone, various benzodiazepines (commonly known under such trade names as Valium and Librium), and synthetic painkillers related to fentanyl, to name but a few.

Semi-synthetic drugs
Semi-synthetic drugs are substances that are found in nature, can be ingested in their natural state for narcotic effects, but can also be chemically processed to produce a different (more potent) synthetic drug. Heroin is the best example of a drug that is classified as semi-synthetic.

Synthetic drugs
Synthetic drugs are those substances that are produced entirely from chemical reactions in a laboratory. Their chemical structure can be identical to naturally occurring drugs, such as cocaine and opium, but they are often designed to enhance effects from naturally occurring drugs, or to prevent side effects that are unwanted. Many purely synthetic compounds with no alternative natural source are classified by the chemical structure of the parent synthetic compound. Drugs that share a common core structure belong to a particular group. But members within a particular group may produce different effects. Pharmacological activity within a group may vary widely.

The members of the ecstasy group are also classified as “designer drugs”. They are structurally related to a controlled drug and produce certain psychoactive effects. They have been designed on the basis of the chemical structure of a given parent drug, and made specifically for sale on the illegal market and to bypass regulations on controlled substances. In response, regulations now commonly cover novel and possible analogues of existing psychoactive substances.

The Problem of Reliability in Illegal Drugs
Illegal drug quality poses a serious threat to the user. In the illegal drug trade neither the buyer nor the seller can be certain of the drug’s content: identity, purity, or strength. Consequences can range from a simple unexpected drug effect to death. Drug impurities may result from sloppy purification processes, clandestinely adding substances to the product to increase its effect, or from chemical degradation, which occurs when drugs are not kept in controlled conditions while they are transported from production to sales. Drug strength, or potency as it is often called on the street, is almost impossible to determine without a laboratory analysis. The buyer may pay more for a low concentration product or may be at risk from a high concentration product. Poor quality street drugs often result in infections, tissue damage, overdose, and life-threatening drug interactions.