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Pharmacology is a branch of
medicine 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 pr ...
,
biology 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 i ...
and
pharmaceutical sciences Pharmacy is the science and practice of discovering, producing, preparing, dispensing, reviewing and monitoring medications, aiming to ensure the safe, effective, and affordable use of medicines. It is a miscellaneous science as it links healt ...
concerned with drug or
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 and ...
action, where a drug may be defined as any artificial, natural, or endogenous (from within the body) molecule which exerts a biochemical or physiological effect on the cell, tissue, organ, or organism (sometimes the word ''pharmacon'' is used as a term to encompass these endogenous and
exogenous In a variety of contexts, exogeny or exogeneity () is the fact of an action or object originating externally. It contrasts with endogeneity or endogeny, the fact of being influenced within a system. Economics In an economic model, an exogeno ...
bioactive species). More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal or abnormal biochemical function. If substances have medicinal properties, they are considered pharmaceuticals. The field encompasses drug composition and properties,functions,sources,synthesis and drug design, molecular and cellular mechanisms, organ/systems mechanisms, signal transduction/cellular communication,
molecular diagnostics Molecular diagnostics is a collection of techniques used to analyze biological markers in the genome and proteome, and how their cells express their genes as proteins, applying molecular biology to medical testing. In medicine the technique is ...
,
interaction Interaction is action that occurs between two or more objects, with broad use in philosophy and the sciences. It may refer to: Science * Interaction hypothesis, a theory of second language acquisition * Interaction (statistics) * Interactions o ...
s, chemical biology, therapy, and medical applications and antipathogenic capabilities. The two main areas of pharmacology are
pharmacodynamics Pharmacodynamics (PD) is the study of the biochemical and physiologic effects of drugs (especially pharmaceutical drugs). The effects can include those manifested within animals (including humans), microorganisms, or combinations of organisms ...
and pharmacokinetics. Pharmacodynamics studies the effects of a drug on biological systems, and pharmacokinetics studies the effects of biological systems on a drug. In broad terms, pharmacodynamics discusses the chemicals with biological
receptors Receptor may refer to: *Sensory receptor, in physiology, any structure which, on receiving environmental stimuli, produces an informative nerve impulse *Receptor (biochemistry), in biochemistry, a protein molecule that receives and responds to a n ...
, and pharmacokinetics discusses the absorption, distribution,
metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run c ...
, and
excretion Excretion is a process in which metabolic waste is eliminated from an organism. In vertebrates this is primarily carried out by the lungs, kidneys, and skin. This is in contrast with secretion, where the substance may have specific tasks after ...
(ADME) of chemicals from the biological systems. Pharmacology is not synonymous with pharmacy and the two terms are frequently confused. Pharmacology, a
biomedical science Biomedical sciences are a set of sciences applying portions of natural science or formal science, or both, to develop knowledge, interventions, or technology that are of use in healthcare or public health. Such disciplines as medical microbi ...
, deals with the research, discovery, and characterization of chemicals which show biological effects and the elucidation of cellular and organismal function in relation to these chemicals. In contrast, pharmacy, a health services profession, is concerned with the application of the principles learned from pharmacology in its clinical settings; whether it be in a dispensing or clinical care role. In either field, the primary contrast between the two is their distinctions between direct-patient care, pharmacy practice, and the science-oriented research field, driven by pharmacology.


Etymology

The word ''pharmacology'' is derived from
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
, ''pharmakon'', "drug, poison" and , ''
-logia ''-logy'' is a suffix in the English language, used with words originally adapted from Ancient Greek ending in ('). The earliest English examples were anglicizations of the French '' -logie'', which was in turn inherited from the Latin '' -logi ...
'' "study of", "knowledge of" (cf. the etymology of ''pharmacy''). Pharmakon is related to
pharmakos A pharmakós ( el, φαρμακός, plural ''pharmakoi'') in Ancient Greek religion was the ritualistic sacrifice or exile of a human scapegoat or victim. Ritual A slave, a cripple, or a criminal was chosen and expelled from the community at tim ...
, the ritualistic sacrifice or exile of a human scapegoat or victim in Ancient Greek religion. The modern term ''pharmacon'' is used more broadly than the term '' drug'' because it includes endogenous substances, and biologically active substances which are not used as drugs. Typically it includes pharmacological
agonists 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 agon ...
and
antagonists An antagonist is a character in a story who is presented as the chief foe of the protagonist. Etymology The English word antagonist comes from the Greek ἀνταγωνιστής – ''antagonistēs'', "opponent, competitor, villain, enemy, ri ...
, but also
enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
inhibitors (such as monoamine oxidase inhibitors).


History

The origins of
clinical pharmacology Clinical pharmacology has been defined as "that discipline that teaches, does research, frames policy, gives information and advice about the actions and proper uses of medicines in humans and implements that knowledge in clinical practice". Clinic ...
date back to the
Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...
, with pharmacognosy and Avicenna's ''
The Canon of Medicine ''The Canon of Medicine'' ( ar, القانون في الطب, italic=yes ''al-Qānūn fī al-Ṭibb''; fa, قانون در طب, italic=yes, ''Qanun-e dâr Tâb'') is an encyclopedia of medicine in five books compiled by Persian physician-phi ...
'',
Peter of Spain __NOTOC__ Peter of Hispania ( la, Petrus Hispanus; Portuguese and es, Pedro Hispano; century) was the author of the ', later known as the ', an important medieval university textbook on Aristotelian logic. As the Latin ''Hispania'' was consider ...
's ''Commentary on Isaac'', and John of St Amand's ''Commentary on the Antedotary of Nicholas''. Early pharmacology focused on
herbalism Herbal medicine (also herbalism) is the study of pharmacognosy and the use of medicinal plants, which are a basis of traditional medicine. With worldwide research into pharmacology, some herbal medicines have been translated into modern reme ...
and natural substances, mainly plant extracts. Medicines were compiled in books called
pharmacopoeia A pharmacopoeia, pharmacopeia, or pharmacopoea (from the obsolete typography ''pharmacopœia'', meaning "drug-making"), in its modern technical sense, is a book containing directions for the identification of compound medicines, and published by ...
s. Crude drugs have been used since prehistory as a preparation of substances from natural sources. However, the
active ingredient An active ingredient is any ingredient that provides biologically active or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease or to affect the structure or any function of the body of humans or animals. The ...
of crude drugs are not purified and the substance is adulterated with other substances.
Traditional medicine Traditional medicine (also known as indigenous medicine or folk medicine) comprises medical aspects of traditional knowledge that developed over generations within the folk beliefs of various societies, including indigenous peoples, before the ...
varies between cultures and may be specific to a particular culture, such as in traditional
Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of ...
, Mongolian, Tibetan and Korean medicine. However much of this has since been regarded as
pseudoscience Pseudoscience consists of statements, beliefs, or practices that claim to be both scientific and factual but are incompatible with the scientific method. Pseudoscience is often characterized by contradictory, exaggerated or unfalsifiable clai ...
. Pharmacological substances known as
entheogen Entheogens are psychoactive substances that induce alterations in perception, mood, consciousness, cognition, or behavior for the purposes of engendering spiritual development or otherwiseRätsch, Christian, ''The Encyclopedia of Psychoac ...
s may have spiritual and religious use and historical context. In the 17th century, the English physician
Nicholas Culpeper Nicholas Culpeper (18 October 1616 – 10 January 1654) was an English botanist, herbalist, physician and astrologer.Patrick Curry: "Culpeper, Nicholas (1616–1654)", ''Oxford Dictionary of National Biography'' (Oxford, UK: OUP, 2004) His bo ...
translated and used pharmacological texts. Culpeper detailed plants and the conditions they could treat. In the 18th century, much of clinical pharmacology was established by the work of
William Withering William Withering FRS (17 March 1741 – 6 October 1799) was an English botanist, geologist, chemist, physician and first systematic investigator of the bioactivity of digitalis. Withering was born in Wellington, Shropshire, the son of a surg ...
. Pharmacology as a scientific discipline did not further advance until the mid-19th century amid the great biomedical resurgence of that period. Before the second half of the nineteenth century, the remarkable potency and specificity of the actions of drugs such as
morphine Morphine is a strong opiate that is found naturally in opium, a dark brown resin in poppies (''Papaver somniferum''). It is mainly used as a pain medication, and is also commonly used recreationally, or to make other illicit opioids. T ...
,
quinine Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to '' Plasmodium falciparum'' that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal le ...
and
digitalis ''Digitalis'' ( or ) is a genus of about 20 species of herbaceous perennial plants, shrubs, and biennials, commonly called foxgloves. ''Digitalis'' is native to Europe, western Asia, and northwestern Africa. The flowers are tubular in shap ...
were explained vaguely and with reference to extraordinary chemical powers and affinities to certain organs or tissues. The first pharmacology department was set up by Rudolf Buchheim in 1847, at University of Tartu, in recognition of the need to understand how therapeutic drugs and poisons produced their effects. Subsequently, the first pharmacology department in
England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
was set up in 1905 at
University College London , mottoeng = Let all come who by merit deserve the most reward , established = , type = Public research university , endowment = £143 million (2020) , budget = ...
. Pharmacology developed in the 19th century as a biomedical science that applied the principles of scientific experimentation to therapeutic contexts. The advancement of research techniques propelled pharmacological research and understanding. The development of the organ bath preparation, where tissue samples are connected to recording devices, such as a
myograph A myograph is any device used to measure the force produced by a muscle when under contraction. Such a device is commonly used in myography, the study of the velocity and intensity of muscular contraction. A myograph can take several forms: for ...
, and physiological responses are recorded after drug application, allowed analysis of drugs' effects on tissues. The development of the
ligand binding assay A ligand binding assay (LBA) is an assay, or an analytic procedure, which relies on the binding of ligand molecules to receptors, antibodies or other macromolecules. A detection method is used to determine the presence and extent of the ligand-recep ...
in 1945 allowed quantification of the
binding affinity In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. The etymology stems from ''ligare'', which means 'to bind'. In protein-ligand binding, the ligand is usually a m ...
of drugs at chemical targets. Modern pharmacologists use techniques from
genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...
,
molecular biology Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physi ...
,
biochemistry Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and ...
, and other advanced tools to transform information about molecular mechanisms and targets into therapies directed against disease, defects or pathogens, and create methods for preventive care, diagnostics, and ultimately
personalized medicine Personalized medicine, also referred to as precision medicine, is a medical model that separates people into different groups—with medical decisions, practices, interventions and/or products being tailored to the individual patient based on the ...
.


Divisions

The discipline of pharmacology can be divided into many sub disciplines each with a specific focus.


Systems of the body

Pharmacology can also focus on specific systems comprising the body. Divisions related to bodily systems study the effects of drugs in different systems of the body. These include
neuropharmacology Neuropharmacology is the study of how drugs affect function in the nervous system, and the neural mechanisms through which they influence behavior. There are two main branches of neuropharmacology: behavioral and molecular. Behavioral neuropharmac ...
, in the central and
peripheral nervous system The peripheral nervous system (PNS) is one of two components that make up the nervous system of bilateral animals, with the other part being the central nervous system (CNS). The PNS consists of nerves and ganglia, which lie outside the brain ...
s; immunopharmacology in the immune system. Other divisions include
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 ...
,
renal The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; bloo ...
and endocrine pharmacology.
Psychopharmacology Psychopharmacology (from Greek grc, ψῡχή, psȳkhē, breath, life, soul, label=none; grc, φάρμακον, pharmakon, drug, label=none; and grc, -λογία, -logia, label=none) is the scientific study of the effects drugs have on mo ...
is the study of the use of drugs that affect the
psyche Psyche (''Psyché'' in French) is the Greek term for "soul" (ψυχή). Psyche may also refer to: Psychology * Psyche (psychology), the totality of the human mind, conscious and unconscious * ''Psyche'', an 1846 book about the unconscious by Car ...
, mind and behavior (e.g. antidepressants) in treating mental disorders (e.g. depression). It incorporates approaches and techniques from neuropharmacology, animal behavior and behavioral neuroscience, and is interested in the behavioral and neurobiological mechanisms of action of psychoactive drugs. The related field of
neuropsychopharmacology Neuropsychopharmacology, an interdisciplinary science related to psychopharmacology (study of effects of drugs on the mind) and fundamental neuroscience, is the study of the neural mechanisms that drugs act upon to influence behavior. It entails ...
focuses on the effects of drugs at the overlap between the nervous system and the psyche.
Pharmacometabolomics Pharmacometabolomics, also known as pharmacometabonomics, is a field which stems from metabolomics, the quantification and analysis of metabolites produced by the body. It refers to the direct measurement of metabolites in an individual's bodily fl ...
, also known as pharmacometabonomics, is a field which stems from
metabolomics Metabolomics is the scientific study of chemical processes involving metabolites, the small molecule substrates, intermediates, and products of cell metabolism. Specifically, metabolomics is the "systematic study of the unique chemical fingerprin ...
, the quantification and analysis of
metabolites In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, ...
produced by the body. It refers to the direct measurement of
metabolites In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, ...
in an individual's bodily fluids, in order to predict or evaluate the
metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run c ...
of
pharmaceutical 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 ...
compounds, and to better understand the pharmacokinetic profile of a drug. Pharmacometabolomics can be applied to measure metabolite levels following the administration of a drug, in order to monitor the effects of the drug on metabolic pathways.
Pharmacomicrobiomics Pharmacomicrobiomics, first proposed by Prof. Marco Candela for the ERC-2009-StG project call (proposal n. 242860, titled "PharmacoMICROBIOMICS, study of the microbiome determinants of the different drug responses between individuals") and later pu ...
studies the effect of microbiome variations on drug disposition, action, and toxicity. Pharmacomicrobiomics is concerned with the interaction between drugs and the gut
microbiome A microbiome () is the community of microorganisms that can usually be found living together in any given habitat. It was defined more precisely in 1988 by Whipps ''et al.'' as "a characteristic microbial community occupying a reasonably wel ...
.
Pharmacogenomics Pharmacogenomics is the study of the role of the genome in drug response. Its name ('' pharmaco-'' + ''genomics'') reflects its combining of pharmacology and genomics. Pharmacogenomics analyzes how the genetic makeup of an individual affects the ...
is the application of genomic technologies to drug discovery and further characterization of drugs related to an organism's entire genome. For pharmacology regarding individual genes,
pharmacogenetics Pharmacogenomics is the study of the role of the genome in drug response. Its name ('' pharmaco-'' + ''genomics'') reflects its combining of pharmacology and genomics. Pharmacogenomics analyzes how the genetic makeup of an individual affects the ...
studies how genetic variation gives rise to differing responses to drugs. Pharmacoepigenetics studies the underlying epigenetic marking patterns that lead to variation in an individual's response to medical treatment. *


Clinical practice and drug discovery

Pharmacology can be applied within clinical sciences.
Clinical pharmacology Clinical pharmacology has been defined as "that discipline that teaches, does research, frames policy, gives information and advice about the actions and proper uses of medicines in humans and implements that knowledge in clinical practice". Clinic ...
is the application of pharmacological methods and principles in the study of drugs in humans. An example of this is posology, which is the study of how medicines are dosed. Pharmacology is closely related to
toxicology Toxicology is a scientific discipline, overlapping with biology, chemistry, pharmacology, and medicine, that involves the study of the adverse effects of chemical substances on living organisms and the practice of diagnosing and treating e ...
. Both pharmacology and toxicology are scientific disciplines that focus on understanding the properties and actions of chemicals. However, pharmacology emphasizes the therapeutic effects of chemicals, usually drugs or compounds that could become drugs, whereas toxicology is the study of chemical's adverse effects and risk assessment. Pharmacological knowledge is used to advise
pharmacotherapy Pharmacotherapy is therapy using pharmaceutical drugs, as distinguished from therapy using surgery (surgical therapy), radiation (radiation therapy), movement (physical therapy), or other modes. Among physicians, sometimes the term ''medical ther ...
in
medicine 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 pr ...
and pharmacy.


Drug discovery

Drug discovery is the field of study concerned with creating new drugs. It encompasses the subfields of
drug design Drug design, often referred to as rational drug design or simply rational design, is the inventive process of finding new medications based on the knowledge of a biological target. The drug is most commonly an organic small molecule that acti ...
and
development Development or developing may refer to: Arts *Development hell, when a project is stuck in development *Filmmaking, development phase, including finance and budgeting *Development (music), the process thematic material is reshaped * Photograph ...
. Drug discovery starts with drug design, which is the inventive process of finding new drugs. In the most basic sense, this involves the design of molecules that are complementary in
shape A shape or figure is a graphical representation of an object or its external boundary, outline, or external surface, as opposed to other properties such as color, texture, or material type. A plane shape or plane figure is constrained to lie ...
and
charge Charge or charged may refer to: Arts, entertainment, and media Films * '' Charge, Zero Emissions/Maximum Speed'', a 2011 documentary Music * ''Charge'' (David Ford album) * ''Charge'' (Machel Montano album) * ''Charge!!'', an album by The Aqu ...
to a given biomolecular target. After a
lead compound A lead compound (, i.e. a "leading" compound, not to be confused with various compounds of the metallic element lead) in drug discovery is a chemical compound that has pharmacology, pharmacological or biological activity likely to be therapeutical ...
has been identified through drug discovery, drug development involves bringing the drug to the market. Drug discovery is related to
pharmacoeconomics Pharmacoeconomics refers to the scientific discipline that compares the value of one pharmaceutical drug or drug therapy to another. It is a sub-discipline of health economics. A pharmacoeconomic study evaluates the cost (expressed in monetary te ...
, which is the sub-discipline of
health economics Health economics is a branch of economics concerned with issues related to efficiency, effectiveness, value and behavior in the production and consumption of health and healthcare. Health economics is important in determining how to improv ...
that considers the value of drugs Pharmacoeconomics evaluates the cost and benefits of drugs in order to guide optimal healthcare resource allocation. The techniques used for the
discovery Discovery may refer to: * Discovery (observation), observing or finding something unknown * Discovery (fiction), a character's learning something unknown * Discovery (law), a process in courts of law relating to evidence Discovery, The Discover ...
, formulation, manufacturing and quality control of drugs discovery is studied by
pharmaceutical engineering Pharmaceutical engineering is a branch of engineering focused on discovering, formulating, and manufacturing medication, analytical and quality control processes, and on designing, building, and improving manufacturing sites that produce drugs. I ...
, a branch of
engineering Engineering is the use of scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and buildings. The discipline of engineering encompasses a broad range of more speciali ...
.
Safety pharmacology Safety pharmacology is a branch of pharmacology specialising in detecting and investigating potential undesirable pharmacodynamic effects of new chemical entities (NCEs) on physiological functions in relation to exposure in the therapeutic range ...
specialises in detecting and investigating potential undesirable effects of drugs. Development of medication is a vital concern to
medicine 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 pr ...
, but also has strong
economical An economic system, or economic order, is a system of production, resource allocation and distribution of goods and services within a society or a given geographic area. It includes the combination of the various institutions, agencies, entitie ...
and
political Politics (from , ) is the set of activities that are associated with making decisions in groups, or other forms of power relations among individuals, such as the distribution of resources or status. The branch of social science that stud ...
implications. To protect the
consumer A consumer is a person or a group who intends to order, or uses purchased goods, products, or services primarily for personal, social, family, household and similar needs, who is not directly related to entrepreneurial or business activities. ...
and prevent abuse, many governments regulate the manufacture, sale, and administration of medication. In the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...
, the main body that regulates pharmaceuticals is the
Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
; they enforce standards set by the
United States Pharmacopoeia The ''United States Pharmacopeia'' (''USP'') is a pharmacopeia (compendium of drug information) for the United States published annually by the United States Pharmacopeial Convention (usually also called the USP), a nonprofit organization that ...
. In the
European Union The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been de ...
, the main body that regulates pharmaceuticals is the EMA, and they enforce standards set by the
European Pharmacopoeia The ''European Pharmacopoeia'' (''Pharmacopoeia Europaea'', ''Ph. Eur.'') is a major regional pharmacopoeia which provides common quality standards throughout the pharmaceutical industry in Europe to control the quality of medicines, and the su ...
. The metabolic stability and the reactivity of a library of candidate drug compounds have to be assessed for drug metabolism and toxicological studies. Many methods have been proposed for quantitative predictions in drug metabolism; one example of a recent computational method is SPORCalc. A slight alteration to the chemical structure of a medicinal compound could alter its medicinal properties, depending on how the alteration relates to the structure of the substrate or receptor site on which it acts: this is called the structural activity relationship (SAR). When a useful activity has been identified, chemists will make many similar compounds called analogues, to try to maximize the desired medicinal effect(s). This can take anywhere from a few years to a decade or more, and is very expensive. One must also determine how safe the medicine is to consume, its stability in the human body and the best form for delivery to the desired organ system, such as tablet or aerosol. After extensive testing, which can take up to six years, the new medicine is ready for marketing and selling. Because of these long timescales, and because out of every 5000 potential new medicines typically only one will ever reach the open market, this is an expensive way of doing things, often costing over 1 billion dollars. To recoup this outlay pharmaceutical companies may do a number of things: * Carefully research the demand for their potential new product before spending an outlay of company funds. * Obtain a patent on the new medicine preventing other companies from producing that medicine for a certain allocation of time. The
inverse benefit law The inverse benefit law states that the ratio of benefits to harms among patients taking new drugs tends to vary inversely with how extensively a drug is marketed. Two Americans, Howard Brody and Donald Light, have defined the inverse benefit law ...
describes the relationship between a drugs therapeutic benefits and its marketing. When designing drugs, the
placebo A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like saline), sham surgery, and other procedures. In general, placebos can af ...
effect must be considered to assess the drug's true therapeutic value. Drug development uses techniques from
medicinal chemistry Medicinal or pharmaceutical chemistry is a scientific discipline at the intersection of chemistry and pharmacy involved with designing and developing pharmaceutical drugs. Medicinal chemistry involves the identification, synthesis and developme ...
to chemically design drugs. This overlaps with the biological approach of finding targets and physiological effects.


Wider contexts

Pharmacology can be studied in relation to wider contexts than the physiology of individuals. For example, pharmacoepidemiology concerns the variations of the effects of drugs in or between populations, it is the bridge between
clinical pharmacology Clinical pharmacology has been defined as "that discipline that teaches, does research, frames policy, gives information and advice about the actions and proper uses of medicines in humans and implements that knowledge in clinical practice". Clinic ...
and
epidemiology Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in a defined population. It is a cornerstone of public health, and shapes policy decisions and evide ...
. Pharmacoenvironmentology or environmental pharmacology is the study of the effects of used pharmaceuticals and personal care products (PPCPs) on the environment after their elimination from the body. Human health and ecology are intimately related so environmental pharmacology studies the environmental effect of drugs and pharmaceuticals and personal care products in the environment. Drugs may also have ethnocultural importance, so ethnopharmacology studies the ethnic and cultural aspects of pharmacology.


Emerging fields

Photopharmacology Photopharmacology, an emerging approach in medicine, involves activating and deactivating photoswitchable molecules with light for target drug delivery. Clinicians use the energy of light to change the shape and chemical properties of a drug, res ...
is an emerging approach in
medicine 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 pr ...
in which drugs are activated and deactivated with
light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 te ...
. The energy of light is used to change for shape and chemical properties of the drug, resulting in different biological activity. This is done to ultimately achieve control when and where drugs are active in a reversible manner, to prevent
side effect In medicine, a side effect is an effect, whether therapeutic or adverse, that is secondary to the one intended; although the term is predominantly employed to describe adverse effects, it can also apply to beneficial, but unintended, consequence ...
s and pollution of drugs into the environment.


Theory of pharmacology

The study of chemicals requires intimate knowledge of the biological system affected. With the knowledge of cell biology and
biochemistry Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and ...
increasing, the field of pharmacology has also changed substantially. It has become possible, through molecular analysis of
receptors Receptor may refer to: *Sensory receptor, in physiology, any structure which, on receiving environmental stimuli, produces an informative nerve impulse *Receptor (biochemistry), in biochemistry, a protein molecule that receives and responds to a n ...
, to design chemicals that act on specific cellular signaling or
metabolic pathway In biochemistry, a metabolic pathway is a linked series of chemical reactions occurring within a cell. The reactants, products, and intermediates of an enzymatic reaction are known as metabolites, which are modified by a sequence of chemical reac ...
s by affecting sites directly on cell-surface receptors (which modulate and mediate cellular signaling pathways controlling cellular function). Chemicals can have pharmacologically relevant properties and effects. Pharmacokinetics describes the effect of the body on the chemical (e.g.
half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable at ...
and
volume of distribution In pharmacology, the volume of distribution (VD, also known as apparent volume of distribution, literally, ''volume of dilution'') is the theoretical volume that would be necessary to contain the total amount of an administered drug at the same c ...
), and
pharmacodynamics Pharmacodynamics (PD) is the study of the biochemical and physiologic effects of drugs (especially pharmaceutical drugs). The effects can include those manifested within animals (including humans), microorganisms, or combinations of organisms ...
describes the chemical's effect on the body (desired or
toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subs ...
).


Systems, receptors and ligands

Pharmacology is typically studied with respect to particular systems, for example endogenous
neurotransmitter systems A neurotransmitter is a signaling molecule secreted by a neuron to affect another cell across a synapse. The cell receiving the signal, any main body part or target cell, may be another neuron, but could also be a gland or muscle cell. Neurotr ...
. The major systems studied in pharmacology can be categorised by their
ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elec ...
s and include acetylcholine,
adrenaline Adrenaline, also known as epinephrine, is a hormone and medication which is involved in regulating visceral functions (e.g., respiration). It appears as a white microcrystalline granule. Adrenaline is normally produced by the adrenal glands an ...
, glutamate, GABA, dopamine,
histamine Histamine is an organic nitrogenous compound involved in local immune responses, as well as regulating physiological functions in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Since histamine was discovered ...
, serotonin,
cannabinoid Cannabinoids () are several structural classes of compounds found in the cannabis plant primarily and most animal organisms (although insects lack such receptors) or as synthetic compounds. The most notable cannabinoid is the phytocannabinoid tet ...
and
opioid Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid use ...
. Molecular targets in pharmacology include receptors,
enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
s and
membrane transport protein A membrane transport protein (or simply transporter) is a membrane protein involved in the movement of ions, small molecules, and macromolecules, such as another protein, across a biological membrane. Transport proteins are integral transmembra ...
s. Enzymes can be targeted with
enzyme inhibitors An enzyme inhibitor is a molecule that binds to an enzyme and blocks its activity. Enzymes are proteins that speed up chemical reactions necessary for life, in which substrate molecules are converted into products. An enzyme facilitates a s ...
. Receptors are typically categorised based on structure and function. Major receptor types studied in pharmacology include
G protein coupled receptors G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily-related p ...
, ligand gated ion channels and
receptor tyrosine kinases Receptor tyrosine kinases (RTKs) are the high- affinity cell surface receptors for many polypeptide growth factors, cytokines, and hormones. Of the 90 unique tyrosine kinase genes identified in the human genome, 58 encode receptor tyrosine kinas ...
.


Pharmacodynamics

Pharmacodynamics is defined as how the body reacts to the drugs. Pharmacology models include the Hill equation, Cheng-Prusoff equation and Schild regression. Pharmacodynamics theory often investigates the
binding affinity In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. The etymology stems from ''ligare'', which means 'to bind'. In protein-ligand binding, the ligand is usually a m ...
of
ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elec ...
s to their receptors. Medication is said to have a narrow or wide ''
therapeutic index The therapeutic index (TI; also referred to as therapeutic ratio) is a quantitative measurement of the relative safety of a drug. It is a comparison of the amount of a therapeutic agent that causes the therapeutic effect to the amount that causes ...
,''
certain safety factor The therapeutic index (TI; also referred to as therapeutic ratio) is a quantitative measurement of the relative safety of a drug. It is a comparison of the amount of a therapeutic agent that causes the therapeutic effect to the amount that causes ...
or ''
therapeutic window The therapeutic index (TI; also referred to as therapeutic ratio) is a quantitative measurement of the relative safety of a drug. It is a comparison of the amount of a therapeutic agent that causes the therapeutic effect to the amount that causes ...
''. This describes the ratio of desired effect to toxic effect. A compound with a narrow therapeutic index (close to one) exerts its desired effect at a dose close to its toxic dose. A compound with a wide therapeutic index (greater than five) exerts its desired effect at a dose substantially below its toxic dose. Those with a narrow margin are more difficult to dose and administer, and may require
therapeutic drug monitoring Therapeutic drug monitoring (TDM) is a branch of clinical chemistry and clinical pharmacology that specializes in the measurement of medication levels in blood. Its main focus is on drugs with a narrow therapeutic range, i.e. drugs that can easily ...
(examples are
warfarin Warfarin, sold under the brand name Coumadin among others, is a medication that is used as an anticoagulant (blood thinner). It is commonly used to prevent blood clots such as deep vein thrombosis and pulmonary embolism, and to prevent st ...
, some
antiepileptic Anticonvulsants (also known as antiepileptic drugs or recently as antiseizure drugs) are a diverse group of pharmacological agents used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of b ...
s,
aminoglycoside Aminoglycoside is a medicinal and bacteriologic category of traditional Gram-negative antibacterial medications that inhibit protein synthesis and contain as a portion of the molecule an amino-modified glycoside (sugar). The term can also refer ...
antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention o ...
). Most anti-
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
drugs have a narrow therapeutic margin: toxic side-effects are almost always encountered at doses used to kill
tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
s. The effect of drugs can be described with Loewe additivity which is one of several common reference models.


Pharmacokinetics

Pharmacokinetics is the study of the bodily absorption, distribution, metabolism, and excretion of drugs. When describing the pharmacokinetic properties of the chemical that is the active ingredient or
active pharmaceutical ingredient An active ingredient is any ingredient that provides biologically active or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease or to affect the structure or any function of the body of humans or animals. The ...
(API), pharmacologists are often interested in ''L-ADME'': * Liberation – How is the API disintegrated (for solid oral forms (breaking down into smaller particles), dispersed, or dissolved from the medication? * Absorption – How is the API absorbed (through the
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different de ...
, the intestine, the
oral mucosa The oral mucosa is the mucous membrane lining the inside of the mouth. It comprises stratified squamous epithelium, termed "oral epithelium", and an underlying connective tissue termed '' lamina propria''. The oral cavity has sometimes been des ...
)? * Distribution – How does the API spread through the organism? *
Metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run c ...
– Is the API converted chemically inside the body, and into which substances. Are these active (as well)? Could they be toxic? *
Excretion Excretion is a process in which metabolic waste is eliminated from an organism. In vertebrates this is primarily carried out by the lungs, kidneys, and skin. This is in contrast with secretion, where the substance may have specific tasks after ...
– How is the API excreted (through the bile, urine, breath, skin)?
Drug metabolism Drug metabolism is the metabolic breakdown of drugs by living organisms, usually through specialized enzymatic systems. More generally, xenobiotic metabolism (from the Greek xenos "stranger" and biotic "related to living beings") is the set o ...
is assessed in pharmacokinetics and is important in drug research and prescribing.


Administration, drug policy and safety


Drug policy

In the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...
, the
Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
(FDA) is responsible for creating guidelines for the approval and use of drugs. The FDA requires that all approved drugs fulfill two requirements: # The drug must be found to be effective against the disease for which it is seeking approval (where 'effective' means only that the drug performed better than placebo or competitors in at least two trials). # The drug must meet safety criteria by being subject to animal and controlled human testing. Gaining FDA approval usually takes several years. Testing done on animals must be extensive and must include several species to help in the evaluation of both the effectiveness and toxicity of the drug. The dosage of any drug approved for use is intended to fall within a range in which the drug produces a
therapeutic effect Therapeutic effect refers to the response(s) after a treatment of any kind, the results of which are judged to be useful or favorable. This is true whether the result was expected, unexpected, or even an unintended consequence. An adverse effect ( ...
or desired outcome. The safety and effectiveness of prescription drugs in the U.S. are regulated by the federal
Prescription Drug Marketing Act of 1987 {{Regulation of therapeutic goods in the United States The Prescription Drug Marketing Act (PDMA) of 1987 (P.L. 100-293, 102 Stat. 95) is a law of the United States federal government. It establishes legal safeguards for prescription drug distri ...
. The Medicines and Healthcare products Regulatory Agency (MHRA) has a similar role in the UK.
Medicare Part D Medicare Part D, also called the Medicare prescription drug benefit, is an optional United States federal-government program to help Medicare beneficiaries pay for self-administered prescription drugs. Part D was enacted as part of the Medi ...
is a prescription drug plan in the U.S. The Prescription Drug Marketing Act (PDMA) is an act related to drug policy. Prescription drugs are drugs regulated by legislation.


Societies and education


Societies and administration

The
International Union of Basic and Clinical Pharmacology The International Union of Basic and Clinical Pharmacology (IUPHAR) is a voluntary, non-profit association representing the interests of scientists in pharmacology-related fields to facilitate ''Better Medicines through Global Education and Rese ...
, Federation of European Pharmacological Societies and European Association for Clinical Pharmacology and Therapeutics are organisations representing standardisation and regulation of clinical and scientific pharmacology. Systems for
medical classification A medical classification is used to transform descriptions of medical diagnoses or procedures into standardized statistical code in a process known as clinical coding. Diagnosis classifications list diagnosis codes, which are used to track diseas ...
of drugs with
pharmaceutical code Pharmaceutical codes are used in medical classification to uniquely identify medication. They may uniquely identify an active ingredient, drug system (including inactive ingredients and time-release agents) in general, or a specific pharmaceutical ...
s have been developed. These include the National Drug Code (NDC), administered by
Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
.;
Drug Identification Number Any product defined as a drug under the Canadian Food and Drugs Act must have an associated drug identification number (or DIN). A DIN also pertains to veterinary drugs permitted for sale in Canada. The drug identification number (DIN) is the 8 d ...
(DIN), administered by Health Canada under the
Food and Drugs Act The ''Food and Drugs Act'' (the ''Act'') (formal title ''An Act respecting food, drugs, cosmetics and therapeutic devices'') is an act of the Parliament of Canada regarding the production, import, export, transport across provinces and sale of f ...
; Hong Kong Drug Registration, administered by the Pharmaceutical Service of the
Department of Health (Hong Kong) Hong Kong's Department of Health is responsible for healthcare policies and the provision of basic healthcare services and established in 1939. The public hospitals are managed by the department's Hospital Authority. The department reports ...
and
National Pharmaceutical Product Index The National Pharmaceutical Product Index or NAPPI is a comprehensive database of pharmaceutical codes for medical products classification used in South Africa South Africa, officially the Republic of South Africa (RSA), is the southernm ...
in South Africa. Hierarchical systems have also been developed, including the
Anatomical Therapeutic Chemical Classification System The Anatomical Therapeutic Chemical (ATC) Classification System is a drug classification system that classifies the active ingredients of drugs according to the organ or system on which they act and their therapeutic, pharmacological and chemic ...
(AT, or ATC/DDD), administered by
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of ...
; Generic Product Identifier (GPI), a hierarchical classification number published by MediSpan and
SNOMED The Systematized Nomenclature of Medicine (SNOMED) is a systematic, computer-processable collection of medical terms, in human and veterinary medicine, to provide codes, terms, synonyms and definitions which cover anatomy, diseases, findings, pr ...
, C axis. Ingredients of drugs have been categorised by
Unique Ingredient Identifier The Unique Ingredient Identifier (UNII) is an alphanumeric identifier linked to a substance's molecular structure or descriptive information and is generated by the Global Substance Registration System (GSRS) of the Food and Drug Administration ...
.


Education

The study of pharmacology overlaps with biomedical sciences and is the study of the effects of drugs on living organisms. Pharmacological research can lead to new drug discoveries, and promote a better understanding of human
physiology Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
. Students of pharmacology must have a detailed working knowledge of aspects in physiology, pathology, and chemistry. They may also require knowledge of plants as sources of pharmacologically-active compounds. Modern pharmacology is interdisciplinary and involves biophysical and computational sciences, and analytical chemistry. A pharmacist needs to be well-equipped with knowledge on pharmacology for application in pharmaceutical research or pharmacy practice in hospitals or commercial organisations selling to customers. Pharmacologists, however, usually work in a laboratory undertaking research or development of new products. Pharmacological research is important in academic research (medical and non-medical), private industrial positions, science writing, scientific patents and law, consultation, biotech and pharmaceutical employment, the alcohol industry, food industry, forensics/law enforcement, public health, and environmental/ecological sciences. Pharmacology is often taught to pharmacy and medicine students as part of a Medical School curriculum.


See also


References


External links


American Society for Pharmacology and Experimental Therapeutics

British Pharmacological Society

International Conference on Harmonisation

US Pharmacopeia

International Union of Basic and Clinical Pharmacology

IUPHAR Committee on Receptor Nomenclature and Drug Classification

IUPHAR/BPS Guide to Pharmacology


Further reading

* * * {{Authority control Biochemistry Life sciences industry