A drug class is a set of

medication A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the medical field an ...

s and other compounds that have a similar

chemical structure A chemical structure determination includes a chemist's specifying the molecular geometry and, when feasible and necessary, the electronic structure of the target molecule or other solid. Molecular geometry refers to the spatial arrangement of a ...

s, the same

mechanism of action In pharmacology, the term mechanism of action (MOA) refers to the specific biochemical interaction through which a drug substance produces its pharmacological effect. A mechanism of action usually includes mention of the specific molecular tar ...

(i.e. binding to the same

biological target A biological target is anything within a living organism to which some other entity (like an endogenous ligand or a drug) is directed and/or binds, resulting in a change in its behavior or function. Examples of common classes of biological targets ...

), a related mode of action, and/or are used to treat the same disease. In several dominant drug classification systems, these four types of classifications form a hierarchy. For example, the fibrates are a chemical class of drugs (amphipathic carboxylic acids) that share the same mechanism of action ( PPAR agonist) and mode of action (reducing blood

triglyceride A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids (from ''tri-'' and '' glyceride''). Triglycerides are the main constituents of body fat in humans and other vertebrates, as ...

s), and that are used to prevent and treat the same disease (

atherosclerosis Atherosclerosis is a pattern of the disease arteriosclerosis in which the wall of the artery develops abnormalities, called lesions. These lesions may lead to narrowing due to the buildup of atheromatous plaque. At onset there are usually ...

). Conversely, not all PPAR agonists are fibrates, not all triglyceride lowering agents are PPAR agonists, and not all drugs used to treat atherosclerosis are triglyceride-lowering agents. A drug class is typically defined by a

prototype drug In pharmacology and pharmaceutics, a prototype drug is an individual drug that represents a drug class – group of medications having similar chemical structures, mechanism of action and mode of action. Prototypes are the most important, and typica ...

, the most important, and typically the first developed drug within the class, used as a reference for comparison.

Comprehensive Systems

* Anatomical Therapeutic Chemical Classification System (ATC) - most widely used. Combines classification by organ system and therapeutic, pharmacological, and chemical properties. * Systematized Nomenclature of Medicine (SNOMED) - includes a section devoted to drug classification

Chemical class

This type of categorisation of drugs is from a

chemical A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., wit ...

perspective and categorises them by their chemical structure. Examples of drug classes that are based on chemical structures include: * β-lactam antibiotic *

Benzodiazepine Benzodiazepines (BZD, BDZ, BZs), sometimes called "benzos", are a class of depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed to treat conditions such as anxiety disorders, ...

Cardiac glycoside Cardiac glycosides are a class of organic compounds that increase the output force of the heart and decrease its rate of contractions by inhibiting the cellular sodium-potassium ATPase pump. Their beneficial medical uses are as treatments for co ...

* Fibrate * Thiazide diuretic *

Steroid A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and ...

* Triptan

Mechanism of action

This type of categorisation is from a

pharmacological Pharmacology is a branch of medicine, biology and pharmaceutical sciences concerned with drug or medication action, where a drug may be defined as any artificial, natural, or endogenous (from within the body) molecule which exerts a biochemic ...

perspective and categorises them by their biological target. Drug classes that share a common molecular

modulate the activity of a specific

. The definition of a mechanism of action also includes the type of activity at that biological target. For receptors, these activities include

agonist An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the ago ...

, antagonist, inverse agonist, or modulator. Enzyme target mechanisms include activator or

inhibitor Inhibitor or inhibition may refer to: In biology * Enzyme inhibitor, a substance that binds to an enzyme and decreases the enzyme's activity * Reuptake inhibitor, a substance that increases neurotransmission by blocking the reuptake of a neurotra ...

. Ion channel modulators include opener or blocker. The following are specific examples of drug classes whose definition is based on a specific mechanism of action: * 5-Alpha-reductase inhibitor * Angiotensin II receptor antagonist * ACE inhibitor * Alpha-adrenergic agonist *

Beta blocker Beta blockers, also spelled β-blockers, are a class of medications that are predominantly used to manage abnormal heart rhythms, and to protect the heart from a second heart attack after a first heart attack ( secondary prevention). They are ...

* Cholinergic *

Dopaminergic Dopaminergic means "related to dopamine" (literally, "working on dopamine"), dopamine being a common neurotransmitter. Dopaminergic substances or actions increase dopamine-related activity in the brain. Dopaminergic brain pathways facilitate do ...

GABAergic In molecular biology and physiology, something is GABAergic or GABAnergic if it pertains to or affects the neurotransmitter GABA. For example, a synapse is GABAergic if it uses GABA as its neurotransmitter, and a GABAergic neuron produces GABA. A ...

* Incretin mimetic *

Nonsteroidal anti-inflammatory drug Non-steroidal anti-inflammatory drugs (NSAID) are members of a therapeutic drug class which reduces pain, decreases inflammation, decreases fever, and prevents blood clots. Side effects depend on the specific drug, its dose and duration of ...

− cyclooxygenase inhibitor * Proton-pump inhibitor * Renin inhibitor *

Selective glucocorticoid receptor modulator Selective glucocorticoid receptor modulators (SEGRMs) and selective glucocorticoid receptor agonists (SEGRAs) formerly known as dissociated glucocorticoid receptor agonists (DIGRAs) are a class of experimental drugs designed to share many of th ...

Serotonergic Serotonergic () or serotoninergic () means "pertaining to or affecting serotonin". Serotonin is a neurotransmitter. A synapse In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chem ...

Statin Statins, also known as HMG-CoA reductase inhibitors, are a class of lipid-lowering medications that reduce illness and mortality in those who are at high risk of cardiovascular disease. They are the most common cholesterol-lowering drugs. L ...

–

HMG-CoA reductase HMG-CoA reductase (3-hydroxy-3-methyl-glutaryl-coenzyme A reductase, official symbol HMGCR) is the rate-controlling enzyme (NADH-dependent, ; NADPH-dependent, ) of the mevalonate pathway, the metabolic pathway that produces cholesterol and ...

inhibitor

Mode of action

This type of categorisation of drugs is from a

biological Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary ...

perspective and categorises them by the anatomical or functional change they induce. Drug classes that are defined by common modes of action (i.e. the functional or anatomical change they induce) include: * Antifungals *

Antimicrobials An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ar ...

Antithrombotics An antithrombotic agent is a drug that reduces the formation of blood clots (thrombi).http://cancerweb.ncl.ac.uk/cgi-bin/omd?antithrombotic Antithrombotics can be used therapeutically for prevention (primary prevention, secondary prevention) or tr ...

Bronchodilator A bronchodilator or broncholytic (although the latter occasionally includes secretory inhibition as well) is a substance that dilates the bronchi and bronchioles, decreasing resistance in the respiratory airway and increasing airflow to the l ...

Chronotrope Chronotropic effects (from ''chrono-'', meaning time, and ''tropos'', "a turn") are those that change the heart rate. Chronotropic drugs may change the heart rate and rhythm by affecting the electrical conduction system of the heart and the ner ...

(positive or negative) * Decongestant *

Diuretic A diuretic () is any substance that promotes diuresis, the increased production of urine. This includes forced diuresis. A diuretic tablet is sometimes colloquially called a water tablet. There are several categories of diuretics. All diuretics in ...

or Antidiuretic *

Inotrope An inotrope is an agent that alters the force or energy of muscular contractions. Negatively inotropic agents weaken the force of muscular contractions. Positively inotropic agents increase the strength of muscular contraction. The term ''inot ...

(positive or negative)

Therapeutic class

This type of categorisation of drugs is from a

medical Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care practi ...

perspective and categorises them by the pathology they are used to treat. Drug classes that are defined by their therapeutic use (the pathology they are intended to treat) include: *

Analgesics An analgesic drug, also called simply an analgesic (American English), analgaesic (British English), pain reliever, or painkiller, is any member of the group of Pharmaceutical drug, drugs used to achieve relief from pain (that is, analgesia or p ...

Antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy, ...

Anticoagulant Anticoagulants, commonly known as blood thinners, are chemical substances that prevent or reduce coagulation of blood, prolonging the clotting time. Some of them occur naturally in blood-eating animals such as leeches and mosquitoes, where t ...

Antidepressant Antidepressants are a class of medication used to treat major depressive disorder, anxiety disorders, chronic pain conditions, and to help manage addictions. Common side-effects of antidepressants include dry mouth, weight gain, dizziness ...

* Anticancer * Antidiabetic * Antiepileptic *

Antipsychotic Antipsychotics, also known as neuroleptics, are a class of psychotropic medication primarily used to manage psychosis (including delusions, hallucinations, paranoia or disordered thought), principally in schizophrenia but also in a range o ...

Antispasmodic An antispasmodic (synonym: spasmolytic) is a pharmaceutical drug or other agent that suppresses muscle spasms. Smooth muscle spasm One type of antispasmodics is used for smooth muscle relaxation, especially in tubular organs of the gastrointestin ...

* Antiviral *

Cardiovascular The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...

Depressant A depressant, or central depressant, is a drug that lowers neurotransmission levels, which is to depress or reduce arousal or stimulation, in various areas of the brain. Depressants are also colloquially referred to as downers as they lower the ...

Sedative A sedative or tranquilliser is a substance that induces sedation by reducing irritability or excitement. They are CNS depressants and interact with brain activity causing its deceleration. Various kinds of sedatives can be distinguished, but ...

Stimulant Stimulants (also often referred to as psychostimulants or colloquially as uppers) is an overarching term that covers many drugs including those that increase activity of the central nervous system and the body, drugs that are pleasurable and inv ...

Amalgamated classes

Some drug classes have been amalgamated from these three principles to meet practical needs. The class of

nonsteroidal anti-inflammatory drugs Non-steroidal anti-inflammatory drugs (NSAID) are members of a therapeutic drug class which reduces pain, decreases inflammation, decreases fever, and prevents blood clots. Side effects depend on the specific drug, its dose and duration of ...

(NSAIDs) is one such example. Strictly speaking, and also historically, the wider class of anti-inflammatory drugs also comprises ''steroidal'' anti-inflammatory drugs. These drugs were in fact the predominant anti-inflammatories during the decade leading up to the introduction of the term "nonsteroidal anti-inflammatory drugs." Because of the disastrous reputation that the corticosteroids had got in the 1950s, the new term, which offered to signal that an anti-inflammatory drug was not a steroid, rapidly gained currency. The drug class of "nonsteroidal anti-inflammatory drugs" (NSAIDs) is thus composed by one element ("anti-inflammatory") that designates the mechanism of action, and one element ("nonsteroidal") that separates it from other drugs with that same mechanism of action. Similarly, one might argue that the class of disease-modifying anti-rheumatic drugs (DMARD) is composed by one element ("disease-modifying") that albeit vaguely designates a mechanism of action, and one element ("anti-rheumatic drug") that indicates its therapeutic use. *

(NSAID) * Disease-modifying antirheumatic drug (DMARD)

Other systems of classification

Other systems of drug classification exist, for example the Biopharmaceutics Classification System which determines a drugs' attributes by solubility and intestinal permeability.

Legal classification

* For the UK legal classification, see Drugs controlled by the UK Misuse of Drugs Act * For the US legal classification, see *For the Canadian legal classification, se
Controlled Drugs and Substances Act
*

Pregnancy category The pregnancy category of a medication is an assessment of the risk of fetal injury due to the pharmaceutical, if it is used as directed by the mother during pregnancy. It does ''not'' include any risks conferred by pharmaceutical agents or their ...

is defined using a variety of systems by different jurisdictions

References

External links

* * {{Medicinal chemistry Pharmacodynamics Medicinal chemistry Pharmacological classification systems