{{Short description|Science of drugs and medications and their effects}}
{{About|the science|the book type ("a pharmacology")|Materia medica|the journal|Skin Pharmacology and Physiology}}
{{Redirect|Pharmacologist|the American Society for Pharmacology and Experimental Therapeutics newsletter|American Society for Pharmacology and Experimental Therapeutics#Publications{{!}}The Pharmacologist}}
{{Distinguish|Pharmacognosy}}
{{cleanup|date=October 2025|reason=1) Order of sections needs to be addressed (e.g., there are 2 sections each for pharmacodynamics and for pharmacokinetics), 2) Several sections are incomplete, 3) Several sections are missing citations}}
{{Use dmy dates|date=March 2014}}

{{Infobox
| abovestyle  = background:red;
| above       = Pharmacology
| image       = [[File:Constant tempertature bath for isolated organs Wellcome M0013241.jpg|class=skin-invert-image|250px]]
| caption     = Diagrammatic representation of organ bath used for studying the effect of isolated tissues
| label1      = MeSH Unique ID
| data1       = [https://www.ncbi.nlm.nih.gov/mesh/68010600 D010600]
}}

'''Pharmacology''' is the science of [[Drug|drugs]] and [[Medication|medications]],<ref>{{cite journal | vauthors = Vallance P, Smart TG | title = The future of pharmacology | journal = British Journal of Pharmacology | volume = 147 Suppl 1 | issue = S1 | pages = S304–7 | date = January 2006 | pmid = 16402118 | pmc = 1760753 | doi = 10.1038/sj.bjp.0706454 }}</ref> including a substance's origin, composition and interaction with [[biological system]]s; specifically through [[pharmacokinetics]], [[pharmacodynamics]], therapeutic use, and [[toxicology]]. The discipline examines these interactions through pharmacokinetics (what the body does to the drug) and pharmacodynamics (what the drug does to the body), both of which determine how a substance alters normal or abnormal [[Biochemistry|biochemical]] function.<ref>{{Cite web |title=Definition of PHARMACOLOGY |url=https://www.merriam-webster.com/dictionary/pharmacology |access-date=2023-02-28 |website=Merriam-Webster |language=en}}</ref> Substances with medicinal properties are classified as [[Pharmaceutical drug|pharmaceuticals]], while the term drug [[mwod:encompasses|encompasses]] any chemical agent that alters biological processes. '''Nanopharmacology''' is the specialization of pharmacology in the [[nanoscale]].<ref>{{Cite journal |last1=Menéndez |first1=Sebastián García |last2=Manucha |first2=Walter |date=2023-01-01 |title=Nanopharmacology as a new approach to treat neuroinflammatory disorders |journal=Translational Neuroscience |volume=14 |issue=1 |article-number=20220328 |doi=10.1515/tnsci-2022-0328 |pmc=10751572 |pmid=38152092}}</ref><ref>{{Citation |last1=Sulochana |first1=G. |chapter=Nanopharmacology and Pharmacotherapeutics |date=2025 |title=Sustainable Nanomaterials for Treatment and Diagnosis of Infectious Diseases |pages=81–112 |publisher=John Wiley & Sons, Ltd |language=en |doi=10.1002/9781394200559.ch4 |isbn=978-1-394-20055-9 |last2=Rajeshkumar |first2=S. |last3=Natarajan |first3=Prabhu Manickam|doi-access=free }}</ref><ref>{{cite journal |last1=Balaji |first1=E Vignesh |last2=Selvan |first2=A Tamil |title=Nanopharmacology: A Novel Approach in Therapeutics |journal=Asian Journal of Research in Pharmaceutical Science |date=2019 |volume=9 |issue=1 |page=9 |doi=10.5958/2231-5659.2019.00003.1 |doi-access=free }}</ref>

The field encompasses drug composition and properties, functions, sources, [[medicinal chemistry]], [[drug design]], molecular and cellular [[mechanism of action|mechanisms]], organ/systems mechanisms, signal transduction/cellular communication, [[molecular diagnostics]], [[drug interaction|interaction]]s, [[chemical biology]], therapy, medical applications, toxicology, and antipathogenic capabilities. The two main areas of pharmacology are [[pharmacodynamics]] 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 [[Receptor (biochemistry)|receptors]], and pharmacokinetics discusses the [[Liberation (pharmacology)|liberation]], [[Absorption (pharmacology)|absorption]], [[Distribution (pharmacology)|distribution]], [[metabolism]], and [[excretion]] ([[LADME]]) of chemicals from the biological systems.

Pharmacology is not synonymous with [[pharmacy]], though the two terms are frequently confused. Pharmacology is a branch of medical and biological sciences which encompasses the research, discovery, and characterization of chemicals exhibiting biological effects, alongside the [[mwod:elucidate|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, pharmaceutics, medicinal chemistry, pharmacognosy, clinical pharmacy and others 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 distinction between direct-patient care, pharmacy practice, and the science-oriented research field, inspired by pharmacology.

==Etymology==
{{See also|Active ingredient}}
The word ''pharmacology'' is derived from [[Ancient Greek|Greek]] word {{lang|grc|[[wikt:φάρμακον|φάρμακον]]}},  ''pharmakon'', meaning "drug" or "[[poison]]", together with another Greek word {{lang|grc|[[wikt:-λογία|-λογία]]}}, ''logia'' with the meaning of "study of" or "knowledge of"<ref>{{cite web | url = http://www.etymonline.com/index.php?term=pharmacy | title = Pharmacy (n.) | work = Online Etymology Dictionary | access-date = 18 May 2017 | archive-date = 2 October 2017 | archive-url = https://web.archive.org/web/20171002165813/http://www.etymonline.com/index.php?term=pharmacy | url-status = live }}</ref><ref>{{cite web | url = http://www.etymonline.com/index.php?term=pharmacology | title = Pharmacology | work = Online Etymology Dictionary | access-date = 18 May 2017 | archive-date = 2 October 2017 | archive-url = https://web.archive.org/web/20171002165736/http://www.etymonline.com/index.php?term=pharmacology | url-status = live }}</ref> (cf. the [[Pharmacy#Etymology|etymology of ''pharmacy'']]). Pharmakon is related to [[pharmakos]], 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]] and [[Receptor antagonist|antagonists]], but also [[enzyme]] inhibitors (such as [[monoamine oxidase]] inhibitors).<ref>{{cite journal | pmid =8877846 |title = Interlaboratory study of log P determination by shake-flask and potentiometric methods | volume=14 | issue=11 | date=Aug 1996 | pages=1405–13|last1 = Takács-Novák |first1 = K. |last2 = Avdeef |first2 = A. |journal = Journal of Pharmaceutical and Biomedical Analysis |doi = 10.1016/0731-7085(96)01773-6 }}</ref>

== History ==
{{main|List of drugs by year of discovery|History of pharmacy}}

[[File:Raw_opium.jpg|thumb|200px|Naturally derived [[opium]] from [[Papaver somniferum|opium poppies]] has been used as a drug since before 1100 BCE.<ref name="Kritikos">{{cite journal|title=The early history of the poppy and opium| vauthors = Kritikos PG, Papadaki SP  |journal=Journal of the Archaeological Society of Athens|date=January 1, 1967}}</ref>]]
[[File:Morphin_-_Morphine.svg|class=skin-invert-image|thumb|200px|Opium's major active constituent, [[morphine]], was first isolated in 1804 and is now known to act as an [[opioid agonist]].<ref name=Luch2009>{{cite book |doi=10.1007/978-3-7643-8336-7 |page=20 |url={{GBurl|MtOiLVWBn8cC|p=20}} |date=2009 |isbn=978-3-7643-8335-0 |title=Molecular, Clinical and Environmental Toxicology |series=Experientia Supplementum |volume=99 |publisher=Birkhäuser Basel |location=Basel |editor1-first=Andreas |editor1-last=Luch }}</ref><ref>{{cite journal | first = Friedrich | last = Sertürner | name-list-style = vanc | date = 1805 | url = {{GBurl|8A09AAAAcAAJ|p=229}} | title = Untitled letter to the editor | journal = Journal der Pharmacie für Aerzte, Apotheker und Chemisten (Journal of Pharmacy for Physicians, Apothecaries, and Chemists) | volume = 13 | pages = 229–243 }}; see especially "III.  Säure im Opium" (acid in opium), pp. 234–235, and  "I.  Nachtrag zur Charakteristik der Säure im Opium" (Addendum on the characteristics of the acid in opium), pp. 236–241.</ref>]]
The origins of [[clinical pharmacology]] date back to the [[Middle Ages]], with [[pharmacognosy]], [[Avicenna]]'s ''[[The Canon of Medicine]]'', [[Peter of Spain (author)|Peter of Spain's]] ''Commentary on Isaac'', and [[John of St Amand]]'s ''Commentary on the Antedotary of Nicholas''.<ref>{{cite journal | vauthors = Brater DC, Daly WJ | title = Clinical pharmacology in the Middle Ages: principles that presage the 21st century | journal = Clinical Pharmacology and Therapeutics | volume = 67 | issue = 5 | pages = 447–50 | date = May 2000 | pmid = 10824622 | doi = 10.1067/mcp.2000.106465 }}</ref> Early pharmacology focused on [[herbalism]] and natural substances, mainly plant extracts while medicines were compiled in books called [[pharmacopoeia]]s. [[Crude drug]]s have been used since prehistory as a preparation of substances from natural sources. However, the [[active ingredient|active pharmaceutical ingredient]] (API) of crude drugs are not purified and the substance is adulterated with other substances.

[[Traditional medicine]] varies between cultures and may be specific to a particular culture, such as in traditional [[Traditional Chinese Medicine|Chinese]], [[Traditional Mongolian medicine|Mongolian]], [[Traditional Tibetan medicine|Tibetan]], and [[Traditional Korean medicine|Korean medicine]]. However much of this has since been regarded as [[pseudoscience]]. Pharmacological substances known as [[entheogen]]s may have spiritual and religious use and a historical context.<ref>{{cite journal |last1=Yuan |first1=Haidan |last2=Ma |first2=Qianqian |last3=Ye |first3=Li |last4=Piao |first4=Guangchun |title=The Traditional Medicine and Modern Medicine from Natural Products |journal=Molecules |date=29 April 2016 |volume=21 |issue=5 |page=559 |doi=10.3390/molecules21050559 |doi-access=free |pmc=6273146 |pmid=27136524}}</ref>

In the 17th century, the English physician [[Nicholas Culpeper]] 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]].<ref>{{cite book | first = Mannfred A. | last = Hollinger | name-list-style = vanc | date = 2003 | url = {{GBurl|bx-WfLwrVH8C|p=4}} | title = Introduction to pharmacology | publisher = [[CRC Press]] | page = 4 | isbn = 0-415-28033-8 }}</ref> Pharmacology as a scientific discipline did not further advance until the mid-19th century amid the great biomedical resurgence of that period.<ref name="rang2006">{{cite journal | vauthors = Rang HP | title = The receptor concept: pharmacology's big idea | journal = British Journal of Pharmacology | volume = 147 Suppl 1 | issue = S1 | pages = S9-16 | date = January 2006 | pmid = 16402126 | pmc = 1760743 | doi = 10.1038/sj.bjp.0706457 }}</ref> Before the second half of the nineteenth century, the remarkable potency and specificity of the actions of drugs such as [[morphine]], [[quinine]], and [[digitalis]] were explained vaguely and with reference to extraordinary chemical powers and affinities to certain organs or tissues.<ref name="AHM2002">{{cite journal | vauthors = Maehle AH, Prüll CR, Halliwell RF | title = The emergence of the drug receptor theory | journal = Nature Reviews. Drug Discovery | volume = 1 | issue = 8 | pages = 637–41 | date = August 2002 | pmid = 12402503 | doi = 10.1038/nrd875 | url = https://durham-repository.worktribe.com/output/1607077 }}</ref> The first pharmacology department was set up by [[Rudolf Buchheim]] in 1847, at the University of Tartu, in recognition of the need to understand how therapeutic drugs and poisons produced their effects.<ref name="rang2006" /> Subsequently, the first [[Department of Pharmacology at University College London, 1905 – 2007|pharmacology department]] in [[England]] was set up in 1905 at [[University College London]].<ref>{{Cite web |title=pA2 Online - Volume 3 - Issue 3 - Pharmacology at University College London |url=http://www.pa2online.org/articles/article.jsp?volume=3&issue=11&article=42 |access-date=2025-11-20 |website=www.pa2online.org}}</ref>

Pharmacology developed in the 19th century as a biomedical science that applied the principles of scientific experimentation to therapeutic contexts.<ref name="rang">{{cite book|title=Pharmacology| vauthors = Rang HP, Dale MM, Ritter JM, Flower RJ |publisher=[[Elsevier]]|year=2007|isbn=978-0-443-06911-6|location=[[China]]}}</ref> 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]], and physiological responses are recorded after drug application, allowed analysis of drugs' effects on tissues. The development of the [[ligand binding assay]] in 1945 allowed quantification of the [[affinity constant|binding affinity]] of drugs at chemical targets.<ref name=MWP2>{{cite book |editor-first1=Masood N. |editor-first2=John W. A. |editor-last1=Khan |editor-last2=Findlay |title=Ligand-Binding Assays |date=2009 |doi=10.1002/9780470541517 |isbn=978-0-470-04138-3 }}{{pn|date=August 2026}}</ref> Modern pharmacologists use techniques from [[genetics]], [[molecular biology]], [[biochemistry]], 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]].

==Divisions==
[[File:Areas within Pharmacology.svg|thumb|Areas within Pharmacology]]
The discipline of pharmacology can be divided into many sub disciplines each with a specific focus.<ref>{{Cite web |title=The Science of Pharmacology & Toxicology |url=https://pharmtox.utoronto.ca/science-pharmacology-toxicology |access-date=2026-03-08 |website=pharmtox.utoronto.ca |language=en}}</ref>

=== Systems of the body ===
Pharmacology can focus on specific [[Human body#Systems|systems]] comprising the body. Divisions related to bodily systems study the effects of drugs in different systems of the body. These include [[neuropharmacology]], in the [[central nervous system|central]] and [[peripheral nervous system]]s; [[immune system|immunopharmacology]] in the immune system. Other divisions include [[Circulatory system|cardiovascular]], [[renal system|renal]], and [[endocrine system|endocrine]] pharmacology. [[Psychopharmacology]] is the study of the use of drugs that affect the [[psyche (psychology)|psyche]], mind, and behavior (e.g. antidepressants) in treating mental disorders (e.g. depression).<ref>{{cite web |title=Psychopharmacology |url=https://www.psychologytoday.com/us/basics/psychopharmacology |website=Psychology Today }}</ref><ref>{{cite web |title=What is Psychopharmacology |url=https://ascpp.org/resources/information-for-patients/what-is-psychopharmacology/ |website=American Society of Clinical Psychopharmacology |date=29 November 2012 }}</ref> 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.<ref>{{Cite journal |last=Robinson |first=Emma |date=2018 |title=Psychopharmacology: From serendipitous discoveries to rationale design, but what next? |journal=Brain and Neuroscience Advances |volume=2 |article-number=2398212818812629 |doi=10.1177/2398212818812629 |pmc=7058199 |pmid=32166162 }}</ref> The related field of [[neuropsychopharmacology]] focuses on the effects of drugs at the overlap between the nervous system and the psyche.<!-- Immuno: 3368
cardio: 1209
renal: 131
endocrine: 69 pubmed results in 2019--><!-- 27632 pubmed results in 2019-->

[[Pharmacometabolomics]], also known as pharmacometabolomics, is a field which stems from [[metabolomics]], the quantification and analysis of [[metabolites]] produced by the body.<ref name="daouk-weinshilboum2008" /><ref name="daouk-weinshilboum2014" /> It refers to the direct measurement of metabolites in an individual's bodily fluids, in order to predict or evaluate the [[metabolism]] of [[pharmaceutical]] compounds, and to better understand the pharmacokinetic profile of a drug.<ref name="daouk-weinshilboum2008" /><ref name="daouk-weinshilboum2014" /> 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]] studies the effect of microbiome variations on drug disposition, action, and toxicity.<ref>{{cite journal | vauthors = Rizkallah MR, Saad R, Aziz RK | title = The Human Microbiome Project, personalized medicine and the birth of pharmacomicrobiomics. | journal = Current Pharmacogenomics and Personalized Medicine | date = September 2010 | volume = 8 | issue = 3 | pages = 182–93 | doi = 10.2174/187569210792246326 }}</ref> Pharmacomicrobiomics is concerned with the interaction between drugs and the gut [[Microbiome of humans|microbiome]]. [[Pharmacogenomics]] 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]] studies how genetic variation gives rise to differing responses to drugs.<ref>{{Cite news |last=PhD |first=Rebecca Roberts |title=Scientists Use Pharmacogenomics to Provide Personalized Medicine |url=https://www.the-scientist.com/scientists-use-pharmacogenomics-to-provide-personalized-medicine-73857 |archive-url=http://web.archive.org/web/20260130121011/https://www.the-scientist.com/scientists-use-pharmacogenomics-to-provide-personalized-medicine-73857 |archive-date=2026-01-30 |access-date=2026-08-09 |work=The Scientist |language=en}}</ref> [[Pharmacoepigenetics]] studies the underlying [[Epigenetics|epigenetic]] marking patterns that lead to variation in an individual's response to medical treatment.<ref>{{cite journal | vauthors = Gomez A, Ingelman-Sundberg M | title = Pharmacoepigenetics: its role in interindividual differences in drug response | journal = Clinical Pharmacology and Therapeutics | volume = 85 | issue = 4 | pages = 426–30 | date = April 2009 | pmid = 19242404 | doi = 10.1038/clpt.2009.2 }}</ref><!-- 11 pubmed results in 2019--><!-- pharmacometabolomics or pharmacometabonomics: 196 pubmed results in 2019--><!-- pharmacogenomics 24700 pubmed results in 2019--><!-- pharmacogenetics: 20383 pubmed results in 2019--><!-- pharmacoepigenetics: 56 pubmed results in 2019-->

===<span class="anchor" id="Posology"></span>Clinical practice and drug discovery===
{{main|Drug development|Drug Discovery Hit to Lead}}

[[File:Toxicology Research at FDA (NCTR 1193) (6009043040).jpg|thumb|right|255px|A [[Toxicology|toxicologist]] working in a lab]]
Pharmacology can be applied within clinical sciences. [[Clinical pharmacology]] is the application of pharmacological methods and principles in the study of drugs in humans.<ref>{{cite web|url=https://www.ascpt.org/Resources/Knowledge-Center/What-is-Clinical-Pharmacology|title=What is Clinical Pharmacology?|website=ascpt.org|access-date=31 October 2021|archive-date=31 October 2021|archive-url=https://web.archive.org/web/20211031021835/https://www.ascpt.org/Resources/Knowledge-Center/What-is-Clinical-Pharmacology|url-status=live}}</ref> An example of this is '''posology''', which is the study of the dosage of medicines.<ref>{{cite web|url=https://www.pharmamad.com/posology/|title=Posology, Factors Influencing Dose, Calculation of Doses|date=23 January 2019|access-date=31 October 2021|website=pharmamad.com|archive-date=31 October 2021|archive-url=https://web.archive.org/web/20211031021837/https://www.pharmamad.com/posology/|url-status=live}}</ref>

Pharmacology is closely related to [[toxicology]]. Both pharmacology and toxicology are scientific disciplines that focus on understanding the properties and actions of chemicals.<ref name="pharmtox">{{cite web|url=https://www.pharmtox.utoronto.ca/science-pharmacology-toxicology|title=The Science of Pharmacology & Toxicology|publisher=Faculty of Medicine, University of Toronto|access-date=July 16, 2019|archive-date=16 July 2019|archive-url=https://web.archive.org/web/20190716151155/https://www.pharmtox.utoronto.ca/science-pharmacology-toxicology|url-status=live}}</ref> 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.<ref name="pharmtox" />

Pharmacological knowledge is used to advise [[pharmacotherapy]] in [[medicine]] and [[pharmacy]].<ref>{{Cite journal |last1=Fasinu |first1=Pius S. |last2=Wilborn |first2=Teresa W. |date=February 2024 |title=Pharmacology education in the medical curriculum: Challenges and opportunities for improvement |journal=Pharmacology Research & Perspectives |volume=12 |issue=1 |article-number=e1178 |doi=10.1002/prp2.1178 |doi-access=free |pmc=10869893 |pmid=38361337}}</ref>

==== Drug discovery ====
{{overly detailed|date=July 2019}}
[[Drug discovery]] is the initial phase of research focused on identifying and validating new chemical compounds ([[lead compound]]s) that are intended to treat a disease.<ref>{{Cite web|title=The Drug Development Process|url=https://www.fda.gov/patients/learn-about-drug-and-device-approvals/drug-development-process|website=FDA|date=2020-02-20|access-date=2025-11-28|language=en|first=Office of the|last=Commissioner}}</ref> [[Drug design]] is an inventive method used within the discovery phase and encompasses the designing of molecules that are complementary in polarity (charge) and shape ([[stereochemistry]]) to a given biomolecular target.<ref>{{cite book |doi=10.1201/b12381 |title=Textbook of Drug Design and Discovery |date=2002 |last1=Smith |first1=H. John |last2=Williams |first2=H. John |isbn=978-0-429-21928-3 |editor-first1=Tommy |editor-first2=Povl |editor-first3=Ulf |editor-last1=Liljefors |editor-last2=Krogsgaard-Larsen |editor-last3=Madsen }}{{page needed|date=March 2025}}</ref><ref>{{cite web|url=https://www.chem.uwec.edu/Chem491_W09/Topic7-2.pdf|title=Introduction to Drug Design|access-date=31 October 2021|archive-date=31 October 2021|archive-url=https://web.archive.org/web/20211031021835/https://www.chem.uwec.edu/Chem491_W09/Topic7-2.pdf|url-status=live}}{{self-published inline|date=March 2025}}</ref> After a lead compound has been identified through drug discovery, drug development involves bringing the drug to the market.<ref>{{Cite web|title=What is an IND? {{!}} Clinical Center|url=https://www.cc.nih.gov/orcs/ind/what-is-an-ind|website=www.cc.nih.gov|access-date=2025-11-28|archive-url=https://web.archive.org/web/20250806154945/https://www.cc.nih.gov/orcs/ind/what-is-an-ind|archive-date=6 August 2025|language=en|url-status=live}}</ref> Drug discovery is related to [[pharmacoeconomics]], which is the sub-discipline of [[health economics]] that considers the value of drugs.<ref>{{cite journal | vauthors = Mueller C, Schur C, O'Connell J | title = Prescription drug spending: the impact of age and chronic disease status | journal = American Journal of Public Health | volume = 87 | issue = 10 | pages = 1626–9 | date = October 1997 | pmid = 9357343 | pmc = 1381124 | doi = 10.2105/ajph.87.10.1626 }}</ref><ref>{{cite journal | vauthors = Arnold RJ, Ekins S | title = Time for cooperation in health economics among the modelling community | journal = PharmacoEconomics | volume = 28 | issue = 8 | pages = 609–13 | year = 2010 | pmid = 20513161 | doi = 10.2165/11537580-000000000-00000 }}</ref> Pharmacoeconomics evaluates the cost and benefits of drugs in order to guide optimal healthcare resource allocation.<ref>{{cite book |doi=10.1016/B978-0-12-802103-3.00034-1 |chapter=Pharmacoeconomics in Healthcare |title=Pharmaceutical Medicine and Translational Clinical Research |date=2018 |last1=Rai |first1=Mahendra |last2=Goyal |first2=Richa |pages=465–472 |isbn=978-0-12-802103-3 }}</ref> The techniques used for the formulation and manufacturing of drugs are studied by [[pharmaceutical engineering]], a branch of engineering.<ref>{{cite journal| vauthors = Reklaitis GV, Khinast J, Muzzio F |date=November 2010|title=Pharmaceutical engineering science—New approaches to pharmaceutical development and manufacturing|journal=Chemical Engineering Science|volume=65|issue=21|pages=iv–vii|doi=10.1016/j.ces.2010.08.041|bibcode=2010ChEnS..65D...4R }}</ref> [[Safety pharmacology]] specializes in detecting and investigating potential undesirable and adverse effects of drugs.<ref>{{Cite journal|last=Hite|first=Mark|date=2016-06-25|title=Safety Pharmacology Approaches|journal=International Journal of Toxicology|language=en|volume=16|pages=23–32|doi=10.1080/109158197227332 |doi-access=free}}</ref><!-- drug discovery/design/development: 34092 pubmed results in 2019--><!-- pharmacoecon: 25523 pubmed results in 2019--><!-- pharmacoengineering or "pharmaceutical engineering" : 4830 pubmed results in 2019--><!-- safety pharm: 848 pubmed results in 2019-->{{AI4 | image = Drug discovery cycle.svg |class=skin-invert-image | image-bg-color = light-dark(white,transparent) | annotations = | align = right | image-width = 300 | width = 300 | height = 225 | alt = Drug discovery cycle schematic | caption =The drug discovery cycle}}

[[Drug development|Development of medication]] is a vital concern to [[medicine]], but also has strong [[economical]] and [[political]] implications. To protect the [[consumer]] and prevent abuse, many governments regulate the manufacture, sale, and administration of medication. In the [[United States]], the main body that regulates pharmaceuticals is the [[Food and Drug Administration]]; they enforce [[Technical standard|standards]] set by the [[United States Pharmacopoeia]]. In the [[European Union]], the main body that regulates pharmaceuticals is the [[European Medicines Agency|European Medicines Agency (EMA)]], and they enforce standards set by the [[European Pharmacopoeia]].<ref>{{Cite web |title=FDA and EMA inspections: Similarities and Differences {{!}} Scilife |url=https://www.scilife.io/blog/fda-and-ema-inspections-pharma |access-date=2026-03-08 |website=www.scilife.io |language=en}}</ref>

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.<ref>{{cite journal | vauthors = Smith J, Stein V | title = SPORCalc: A development of a database analysis that provides putative metabolic enzyme reactions for ligand-based drug design | journal = Computational Biology and Chemistry | volume = 33 | issue = 2 | pages = 149–59 | date = April 2009 | pmid = 19157988 | doi = 10.1016/j.compbiolchem.2008.11.002 }}</ref> 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.<ref name="ReviseALChem">{{cite book |title=Revise A2 Chemistry |chapter=What's in a Medicine (WM) |chapter-url={{GBurl|4vtRp_03vFYC|pg=RA1-PA1}} |last1=Newton|first1=David| first2 = Alasdair | last2 = Thorpe | first3 = Chris | last3 = Otter | name-list-style = vanc |publisher=[[Heinemann Educational Publishers]]|year=2004|isbn=0-435-58347-6|page=1}}</ref> 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.<ref name="ReviseALChem" />

Because of these long timescales and the fact that only one out of every 5000 potential new medicines will ever reach the open market, this is an expensive way of doing things, often costing over 1 USD billion per drug. To recoup this outlay, pharmaceutical companies may do a number of things:<ref name="ReviseALChem" />
* Carefully research the demand for their potential new product before spending an outlay of company funds.<ref name="ReviseALChem" />
* Obtain a patent on the new medicine preventing other companies from producing that medicine for a certain allocation of time.<ref name="ReviseALChem" />

The [[Inverse benefit law|Inverse Benefit Law]] describes the relationship between a drug's therapeutic benefits and the socioeconomic status (overall health risk/need) of the population undergoing treatment. The law states that the therapeutic benefit conferred by medical interventions upon a population is inversely proportional to its [[Incidence (epidemiology)|incidence of disease]] or socioeconomic need.<ref>{{Cite journal|title=The inverse benefit law: how drug marketing undermines patient safety and public health|journal=American Journal of Public Health|date=March 2011 |pmc=3036704|pmid=21233426|pages=399–404|volume=101|issue=3|doi=10.2105/AJPH.2010.199844|first1=Howard|last1=Brody|first2=Donald W.|last2=Light}}</ref>

When designing drugs, the [[placebo]] effect must be considered to assess the drug's true therapeutic value.

Drug development uses techniques from [[medicinal chemistry]] 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]] and [[epidemiology]].<ref>{{Cite book |title=Rang and Dale's pharmacology |first1=James |last1=Ritter |first2=Rod J. |last2=Flower |first3=G. |last3=Henderson |first4=David J. |last4=MacEwan |first5=Yoon Kong |last5=Loke |first6=H. P. |last6=Rang |publisher=Elsevier |year=2020|isbn=978-0-7020-8060-9|edition=Ninth|location=Edinburgh|oclc=1081403059}}{{page needed|date=March 2025}}</ref><ref>{{cite book |doi=10.1002/9781119701101.ch2 |chapter=Study Designs Available for Pharmacoepidemiologic Studies |title=Textbook of Pharmacoepidemiology |date=2021 |last1=Strom |first1=Brian L. |pages=20–34 |isbn=978-1-119-70107-1 }}</ref> [[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.<ref>{{cite journal | vauthors = Rahman SZ, Khan RA, Gupta V, Uddin M | title = Pharmacoenvironmentology--a component of pharmacovigilance | journal = Environmental Health | volume = 6 | issue = 1 | article-number = 20 | date = July 2007 | pmid = 17650313 | pmc = 1947975 | doi = 10.1186/1476-069X-6-20 | bibcode = 2007EnvHe...6...20R | doi-access = free }}</ref> 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]].<ref>{{cite journal |last1=Jena |first1=Monalisa |last2=Mishra |first2=Archana |last3=Maiti |first3=Rituparna |title=Environmental pharmacology: source, impact and solution |journal=Reviews on Environmental Health |date=26 March 2019 |volume=34 |issue=1 |pages=69–79 |doi=10.1515/reveh-2018-0049 |pmid=30854834 |bibcode=2019RvEH...34...69J }}</ref>

Drugs may also have ethnocultural importance, so [[ethnopharmacology]] studies the ethnic and cultural aspects of pharmacology.<ref name="int-soc-ethnopharm">{{Cite web|title=International Society for Ethnopharmacology|url=https://ethnopharmacology.org/|access-date=2021-02-04|website=International Society for Ethnopharmacology|language=en-US|archive-date=21 January 2021|archive-url=https://web.archive.org/web/20210121205853/https://ethnopharmacology.org/|url-status=live}}</ref> <!-- pharmacoepidem: 8974 pubmed results in 2019--><!-- environmental pharm: 22 pubmed results in 2019-->

=== Emerging fields ===
[[Photopharmacology]] is an emerging approach in [[medicine]] in which drugs are activated and deactivated with [[light]]. The energy of light is used to change for shape and chemical properties of the drug, resulting in different biological activity.<ref>{{cite journal |last1=Ricart-Ortega |first1=Maria |last2=Font |first2=Joan |last3=Llebaria |first3=Amadeu |title=GPCR photopharmacology |journal=Molecular and Cellular Endocrinology |date=May 2019 |volume=488 |pages=36–51 |doi=10.1016/j.mce.2019.03.003 |pmid=30862498 |hdl=10261/201805 |hdl-access=free }}</ref> This is done to ultimately achieve control when and where drugs are active in a reversible manner, to prevent [[side effect]]s and pollution of drugs into the environment.<ref>{{cite journal |last1=Velema |first1=Willem A. |last2=Szymanski |first2=Wiktor |last3=Feringa |first3=Ben L. |title=Photopharmacology: Beyond Proof of Principle |journal=Journal of the American Chemical Society |date=12 February 2014 |volume=136 |issue=6 |pages=2178–2191 |doi=10.1021/ja413063e |pmid=24456115 |bibcode=2014JAChS.136.2178V |url=https://pure.rug.nl/ws/files/13153399/ja_2013_13063e_photopharma_revised.pdf }}</ref><ref>{{cite journal | vauthors = Broichhagen J, Frank JA, Trauner D | title = A roadmap to success in photopharmacology | journal = Accounts of Chemical Research | volume = 48 | issue = 7 | pages = 1947–60 | date = July 2015 | pmid = 26103428 | doi = 10.1021/acs.accounts.5b00129 | bibcode = 2015AcChR..48.1947B }}</ref>

[[Epigenetic therapy]] may offer an alternative 'master switch' to gene therapy to introduce persistent changes to the phenotype. Aging is well-known to be measurable through [[epigenetic clock]].<ref>{{cite journal |last1=Dai |first1=Wanlin |last2=Qiao |first2=Xinbo |last3=Fang |first3=Yuanyuan |last4=Guo |first4=Renhao |last5=Bai |first5=Peng |last6=Liu |first6=Shuang |last7=Li |first7=Tingting |last8=Jiang |first8=Yutao |last9=Wei |first9=Shuang |last10=Na |first10=Zhijing |last11=Xiao |first11=Xue |last12=Li |first12=Da |title=Epigenetics-targeted drugs: current paradigms and future challenges |journal=Signal Transduction and Targeted Therapy |date=26 November 2024 |volume=9 |issue=1 |article-number=332 |doi=10.1038/s41392-024-02039-0 |doi-access=free |pmid=39592582 |pmc=11627502 }}</ref>

Drugs may induce ''persistent changes''. When they cause drugs to lose efficacy, it is called [[drug tolerance]]. On the other hand, they may introduce benign changes to the body. [[Psychoplastogen]] produce profound effects by regulating [[neuroplasticity]]. [[Psychostimulants]] prevent grey matter loss in ADHD patients, at therapeutic doses.<ref>{{cite journal |last1=Pretus |first1=Clara |last2=Ramos-Quiroga |first2=J. Antoni |last3=Richarte |first3=Vanessa |last4=Corrales |first4=Montse |last5=Picado |first5=Marisol |last6=Carmona |first6=Susanna |last7=Vilarroya |first7=Óscar |title=Time and psychostimulants: Opposing long-term structural effects in the adult ADHD brain. A longitudinal MR study |journal=European Neuropsychopharmacology |date=December 2017 |volume=27 |issue=12 |pages=1238–1247 |doi=10.1016/j.euroneuro.2017.10.035 |pmid=29129558 }}</ref> <!-- 28 pubmed results in 2019: Pharmacocybernetics or pharma-cybernetics or "cybernetic pharmacy" or cyberpharmacy
--><!-- 101 pubmed results in 2019--><!-- 688 pubmed results in 2019-->

== Theory of pharmacology ==
{{Expand section|date=July 2019}}
Pharmacology is the scientific study of drugs and their interactions with living systems. it is broadly divided into two main branches: [[pharmacokinetics]] and [[pharmacodynamics]].

=== Pharmacokinetics ===
Pharmacokinetics refers to the movement of drugs within the body and describes what the body does to a drug.<ref>{{cite journal |last1=Martínez |first1=Guillermo |last2=Vázquez |first2=Juan |last3=Begines |first3=Belén |last4=Alcudia |first4=Ana |title=Emerging Strategies to Improve the Design and Manufacturing of Biocompatible Therapeutic Materials |journal=Pharmaceutics |date=12 July 2023 |volume=15 |issue=7 |pages=1938 |doi=10.3390/pharmaceutics15071938 |doi-access=free |pmc=10383592 |pmid=37514123}}</ref><ref>{{Cite journal |last1=Ruiz-Garcia |first1=Ana |last2=Bermejo |first2=Marival |last3=Moss |first3=Aaron |last4=Casabo |first4=Vicente G. |date=February 2008 |title=Pharmacokinetics in drug discovery |journal=Journal of Pharmaceutical Sciences |volume=97 |issue=2 |pages=654–690 |doi=10.1002/jps.21009 |pmid=17630642 |bibcode=2008JPhmS..97..654R }}</ref> It includes five main processes:
* '''[[Liberation (pharmacology)|Liberation]]''' '''–''' When the [[active pharmaceutical ingredient]] is released from its [[pharmaceutical formulation]] and becomes available for absorption.<ref>{{Cite journal |last1=Dredán |first1=Judit |last2=Csóka |first2=Gabriella |last3=Marton |first3=Sylvia |last4=Antal |first4=István |date=2003 |title=A határfelületi tulajdonságok jelentősége a gyógyszertechnológiában |trans-title=Importance of interfacial characteristics in pharmaceutical technology |journal=Acta Pharmaceutica Hungarica |volume=73 |issue=3 |pages=147–151 |pmid=15112437 |language=hu }}</ref>
* '''[[Absorption (pharmacology)|Absorption]] –''' How the drug enters the bloodstream.
* '''[[Distribution (pharmacology)|Distribution]] –''' How the drug spreads throughout the body's tissue and fluids.
* '''[[Metabolism]] –''' How the drug is chemically altered, primarily in the liver.
* '''[[Excretion]] –''' How the drug and its metabolites are eliminated, mainly through the kidneys.

==== Key physiological parameters in pharmacokinetics include ====
* '''[[Half-life|Half-life (''t''<sub>½</sub>)]]''' '''–''' The time required for the drug's plasma concentration to reduce by half.
* '''[[Volume of distribution|Volume of distribution (''V<sub>D</sub>'')]] –''' A theoretical volume that relates the total amount of a drug in the body to its measured concentration in the blood (or plasma).
* '''[[Clearance (pharmacology)|Total Clearance (''Cl''<sub>tot</sub>)]] –''' A theoretical pharmacokinetic parameter that statistically explains the efficiency with which a drug is irreversibly eliminated from the body, quantified as the volume of plasma cleared of the drug per unit of time, typically measured in L/h or mL/min.<ref>{{Cite journal |last1=Korzekwa |first1=Ken |last2=Nagar |first2=Swati |date=April 2023 |title=Process and System Clearances in Pharmacokinetic Models: Our Basic Clearance Concepts Are Correct |journal=Drug Metabolism and Disposition: The Biological Fate of Chemicals |volume=51 |issue=4 |pages=532–542 |doi=10.1124/dmd.122.001060 |pmc=10043942 |pmid=36623886}}</ref>
* [[Area under the curve (pharmacokinetics)|'''Area Under the Curve (AUC)''']] '''–''' The definite integral of the plasma drug concentration versus time curve from time zero to infinity, which represents the total systemic exposure of the body to a drug overtime (AUC<sub>0</sub>−∞).<ref>{{Cite journal |last1=Scheff |first1=Jeremy D. |last2=Almon |first2=Richard R. |last3=Dubois |first3=Debra C. |last4=Jusko |first4=William J. |last5=Androulakis |first5=Ioannis P. |date=May 2011 |title=Assessment of pharmacologic area under the curve when baselines are variable |journal=Pharmaceutical Research |volume=28 |issue=5 |pages=1081–1089 |doi=10.1007/s11095-010-0363-8 |pmc=3152796 |pmid=21234658 }}</ref>

=== Pharmacodynamics ===
Pharmacodynamics refers to the biochemical and physiological effects of drugs on the body and the mechanism of the action. it answers the question, "What does the drug do to the body?"

This include :

* '''[[Receptor (biochemistry)|Receptor binding]]''' – Most drugs exert their effects by binding to specific cell receptors (proteins on cell surfaces or inside cells)
* '''[[Dose–response relationship|Dose-response relationship]]''' – Illustrated using drug-response curves, these relationships show the effect of different drug doses on the magnitude of a response.
* '''[[Therapeutic index|Therapeutic window]]''' – The range of doses between the minimum effective concentration and the minimum toxic concentration.

[[File:Dose response antagonist.jpg|class=skin-invert-image|thumb|400px|right|A trio of [[dose response curve]]s. Dose response curves are studied extensively in pharmacology.]]

=== Systems, receptors and ligands ===
{{Expand section|date=July 2019}}
{{Main|Ligand (biochemistry)|List of drugs|Neurotransmitter}}

[[File:Cholinergic synapse.svg|class=skin-invert-image|thumb|300px|The [[acetylcholine|cholinergic]] synapse. Targets in synapses can be modulated with pharmacological agents. In this case, [[cholinergic]]s (such as [[muscarine]]) and [[anticholinergic]]s (such as [[atropine]]) target receptors; [[Reuptake modulator|transporter inhibitors]] (such as [[hemicholinium]]) target membrane transport proteins and [[anticholinesterase]]s (such as [[sarin]]) target enzymes.]]

Pharmacology is often studied by focusing on specific systems, such as endogenous neurotransmitter systems. The major systems studied in pharmacology can be categorized by their [[ligand (biochemistry)|ligand]]s and their [[Receptor (biochemistry)|receptors]] which include, but are not limited to, [[acetylcholine|acetylcholine (ACh)]], [[adenosine]], [[adrenaline]], [[anandamide]], [[Aspartic acid|aspartate]], [[glutamate]], [[glycine]], [[purine]]s, [[substance P]], [[eicosanoid]]s, [[GABA]], [[dopamine|dopamine (DA)]], [[histamine]], [[Serotonin|serotonin (5-HT)]], [[serine]], [[cannabinoid]]s, [[opioid]]s, [[melatonin]], [[Vasopressin|vasopressin (ADH)]], and [[Norepinephrine|norepinephrine (NE).]]<ref>{{cite journal |last1=Hyman |first1=Steven E. |title=Neurotransmitters |journal=Current Biology |date=March 2005 |volume=15 |issue=5 |pages=R154–R158 |doi=10.1016/j.cub.2005.02.037 |pmid=15753022 |bibcode=2005CBio...15.R154H }}</ref><ref>{{cite book |last1=Cuevas |first1=Javier |title=Reference Module in Biomedical Sciences |chapter=Neurotransmitters and Their Life Cycle |date=2019 |doi=10.1016/B978-0-12-801238-3.11318-2 |isbn=978-0-12-801238-3 }}</ref>

Molecular targets in pharmacology include receptors, [[enzyme]]s, and [[membrane transport protein]]s. Enzymes can be targeted with [[enzyme inhibitors]]. Receptors are typically categorized based on structure and function. Major receptor types studied in pharmacology include [[G protein coupled receptors]], [[ligand gated ion channels]], and [[receptor tyrosine kinases]].<ref>{{Cite web |last=Themes |first=U. F. O. |date=2021-05-20 |title=Molecular mechanisms of drug actions |url=https://musculoskeletalkey.com/molecular-mechanisms-of-drug-actions/ |access-date=2026-03-05 |website=Musculoskeletal Key |language=en-US}}</ref>

Network pharmacology is a subfield of pharmacology that combines principles from pharmacology, [[systems biology]], and network analysis to study the complex interactions between drugs and targets (receptors or enzymes etc.) in biological systems. The topology of a biochemical reaction network determines the shape of drug [[dose-response relationship|dose-response curve]]<ref>{{cite journal |last1=van Wijk |first1=Roeland |last2=Tans |first2=Sander J. |last3=Wolde |first3=Pieter Rein ten |last4=Mashaghi |first4=Alireza |title=Non-monotonic dynamics and crosstalk in signaling pathways and their implications for pharmacology |journal=Scientific Reports |date=18 June 2015 |volume=5 |issue=1 |article-number=11376 |doi=10.1038/srep11376  |doi-access=free|pmid=26087464 |pmc=5155565 |bibcode=2015NatSR...511376V }}</ref> as well as the type of drug-drug interactions,<ref name="Mehrad Babaei 2023">{{cite journal |last1=Babaei |first1=Mehrad |last2=Evers |first2=Tom M.J. |last3=Shokri |first3=Fereshteh |last4=Altucci |first4=Lucia |last5=de Lange |first5=Elizabeth C.M. |last6=Mashaghi |first6=Alireza |title=Biochemical reaction network topology defines dose-dependent Drug–Drug interactions |journal=Computers in Biology and Medicine |date=March 2023 |volume=155 |article-number=106584 |doi=10.1016/j.compbiomed.2023.106584 |pmid=36805215 |hdl=1887/3632248 |hdl-access=free }}</ref> thus can help designing efficient and safe therapeutic strategies. The topology Network pharmacology utilizes computational tools and network analysis algorithms to identify drug targets, predict drug-drug interactions, elucidate signaling pathways, and explore the [[polypharmacology]] of drugs.

=== Pharmacodynamics ===
{{More citations needed section|date=November 2023}}
{{Main|Pharmacodynamics}}

Pharmacodynamics is defined as how the body reacts to the drugs. Pharmacodynamics theory often investigates the [[binding affinity]] of [[ligand (biochemistry)|ligand]]s to their receptors. Ligands can be [[agonist]]s, partial agonists or [[Receptor antagonist|antagonists]] at specific receptors in the body. Agonists bind to receptors and produce a biological response, a partial agonist produces a biological response lower than that of a full agonist, antagonists have affinity for a receptor but do not produce a biological response.

The ability of a ligand to produce a biological response is termed [[Intrinsic activity|efficacy]], in a dose-response profile it is indicated as percentage on the y-axis, where 100% is the maximal efficacy (all receptors are occupied).

Binding affinity is the ability of a ligand to form a ligand-receptor complex either through [[Van der Waals force|weak attractive forces]] (reversible) or [[covalent bond]] (irreversible), therefore efficacy is dependent on binding affinity.

[[Potency (pharmacology)|Potency]] of drug is the measure of its effectiveness, [[EC50|EC<sub>50</sub>]] is the drug concentration of a drug that produces an efficacy of 50% and the lower the concentration the higher the potency of the drug therefore EC<sub>50</sub> can be used to compare potencies of drugs.

Medication is said to have a narrow or wide ''[[therapeutic index]],'' [[certain safety factor]], or ''[[therapeutic window]]''. 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]] (examples are [[warfarin]], some [[antiepileptic]]s, [[aminoglycoside]] [[antibiotics]]). Most anti-[[cancer]] drugs have a narrow therapeutic margin: toxic side-effects are almost always encountered at doses used to kill [[tumor]]s.

The effect of drugs can be described with [[Loewe additivity]] which is one of several common reference models.<ref name="Mehrad Babaei 2023"/>

Other models include the [[Hill equation (biochemistry)|Hill equation]], [[Cheng–Prusoff equation]] and [[Schild regression]].

=== Pharmacokinetics ===
{{Multiple issues|section=yes|{{expand section|date=July 2019}}
{{cleanup section|reason=Content needs to be generalised to encompass pharmacokinetics as a whole, not just individual ideas.|date=July 2019}}}}
{{Main|Pharmacokinetics}}

[[Pharmacokinetics]] is the study of the bodily absorption, distribution, metabolism, and excretion of drugs.<ref>{{cite web |url= https://www.merriam-webster.com/dictionary/pharmacokinetics |title= Pharmacokinetics |website= Merriam-Webster |access-date= July 16, 2019 |archive-date= 16 July 2019 |archive-url= https://web.archive.org/web/20190716151748/https://www.merriam-webster.com/dictionary/pharmacokinetics |url-status= live }}</ref>

When describing the pharmacokinetic properties of the chemical that is the active ingredient or [[Active ingredient|active pharmaceutical ingredient]], pharmacologists are often interested in ''L-ADME'':
* [[Liberation (pharmacology)|Liberation]] – How is the active pharmaceutical ingredient disintegrated (for solid oral forms (breaking down into smaller particles), dispersed, or dissolved from the medication?
* [[Absorption (digestive)|Absorption]] – How is the active pharmaceutical ingredient absorbed (through the [[human skin|skin]], the [[intestine]], the [[oral mucosa]])?
* [[Distribution (pharmacology)|Distribution]] – How does the active pharmaceutical ingredient spread through the organism?
* [[Drug metabolism|Metabolism]] – Is the active pharmaceutical ingredient converted chemically inside the body, and into which substances. Are these active (as well)? Could they be toxic?
* [[Excretion]] – How is the active pharmaceutical ingredient excreted (through the bile, urine, breath, skin)?

[[Drug metabolism]] is assessed in pharmacokinetics and is important in drug research and prescribing.

Pharmacokinetics is the movement of the drug in the body, it is usually described as 'what the body does to the drug' the physico-chemical properties of a drug will affect the rate and extent of absorption, extent of distribution, metabolism and elimination. The drug needs to have the appropriate molecular weight, polarity etc. in order to be absorbed, the fraction of a drug that reaches the systemic circulation is termed bioavailability, this is simply a ratio of the peak plasma drug levels after oral administration and the drug concentration after an IV administration (first pass effect is avoided and therefore no amount drug is lost). A drug must be lipophilic (lipid soluble) in order to pass through biological membranes because biological membranes are made up of a lipid bilayer (phospholipids etc.). Once the drug reaches the blood circulation it is then distributed throughout the body and being more concentrated in highly perfused organs.

=== Gene expression modulation and epigenetics ===
Apart from classical pharmacological targets, drugs may exert effects through direct or indirect gene expression [[Therapeutic gene modulation|modulation]], or even introduce persistent state changes through epigenetic [[reprogramming]].

Therefore, drugs should be screened for [[off-target activity]] by [[gene expression profiling]], in addition to conventional ligand binding, enzyme assays, etc.

== Administration, drug policy and safety ==
=== Drug policy ===
{{Main|Drug policy}}

In the [[United States]], the [[Food and Drug Administration]] (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]] or desired outcome.<ref name=nagle>{{cite book|last1=Nagle|first1=Hinter | first2 = Barbara | last2 = Nagle | name-list-style = vanc |title=Pharmacology: An Introduction|year=2005|publisher=[[McGraw Hill]]|location=[[Boston]]|isbn=978-0-07-312275-5}}{{page needed|date=March 2025}}</ref>

The safety and effectiveness of prescription drugs in the U.S. are regulated by the federal [[Prescription Drug Marketing Act (PDMA)|Prescription Drug Marketing Act of 1987]].

The [[Medicines and Healthcare products Regulatory Agency]] (MHRA) has a similar role in the UK.

[[Medicare Part D]] is a prescription drug plan in the U.S.

The [[Prescription Drug Marketing Act (PDMA)]] is an act related to drug policy.

[[Prescription drug]]s are drugs regulated by legislation.

== Societies and education ==
{{unreferenced section|date=February 2016}}

=== Societies and administration ===
The [[International Union of Basic and Clinical Pharmacology]], [[Federation of European Pharmacological Societies]], and [[European Association for Clinical Pharmacology and Therapeutics]] are organizations representing standardization and regulation of clinical and scientific pharmacology.

Systems for [[medical classification]] of drugs with [[pharmaceutical code]]s have been developed. These include the [[National Drug Code]] (NDC), administered by [[Food and Drug Administration]];<ref>{{cite web|url=https://www.fda.gov/drugs/drug-approvals-and-databases/national-drug-code-directory?elqTrackId=b2f8af5cd98146b19b56b47feab2f6a0&elq=b28e6c325c6748e1bc1f24989a3eb0d6&elqaid=4255&elqat=1&elqCampaignId=3344|title=National Drug Code Directory|date=5 May 2017|website=U.S. Food and Drug Administration|access-date=28 May 2019|archive-date=27 May 2016|archive-url=https://web.archive.org/web/20160527135726/http://www.fda.gov/Drugs/InformationOnDrugs/ucm142438.htm|url-status=live}}</ref> [[Drug Identification Number]] (DIN), administered by [[Health Canada]] under the [[Food and Drugs Act]]; [[Department of Health (Hong Kong)#Hong Kong Drug Registration|Hong Kong Drug Registration]], administered by the Pharmaceutical Service of the [[Department of Health (Hong Kong)]], and [[National Pharmaceutical Product Index]] in South Africa. Hierarchical systems have also been developed, including the [[Anatomical Therapeutic Chemical Classification System]] (AT, or ATC/DDD), administered by [[World Health Organization]]; [[Generic Product Identifier]], a hierarchical classification number published by MediSpan and [[SNOMED]], C axis. Ingredients of drugs have been categorized by [[Unique Ingredient Identifier]]s.

=== Education ===
{{Main|Medical 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]]. 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.<ref name="int-soc-ethnopharm" />  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 organizations 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 ==
{{Portal|Biology}}
{{Columns-list|colwidth=30em|
* [[Cosmeceuticals]]
* [[List of abbreviations used in medical prescriptions]]
* [[List of pharmaceutical companies]]
* [[List of withdrawn drugs]]
* [[Pharmaceutical company]]
* [[Pharmaceutical formulation]]
* [[Pharmaceutical physician]]
}}

== References ==
{{Reflist|refs=
<ref name=daouk-weinshilboum2008>{{cite journal | vauthors = Kaddurah-Daouk R, Kristal BS, Weinshilboum RM | title = Metabolomics: a global biochemical approach to drug response and disease | journal = Annual Review of Pharmacology and Toxicology | volume = 48 | pages = 653–83 | year = 2008 | pmid = 18184107 | doi = 10.1146/annurev.pharmtox.48.113006.094715 }}</ref>
<ref name=daouk-weinshilboum2014>{{cite journal | vauthors = Kaddurah-Daouk R, Weinshilboum RM | title = Pharmacometabolomics: implications for clinical pharmacology and systems pharmacology | journal = Clinical Pharmacology and Therapeutics | volume = 95 | issue = 2 | pages = 154–67 | date = February 2014 | pmid = 24193171 | doi = 10.1038/clpt.2013.217 }}</ref>
}}

== External links ==
{{Commons category}}
* [http://www.aspet.org American Society for Pharmacology and Experimental Therapeutics]
* [http://www.bps.ac.uk British Pharmacological Society]
* [http://www.ich.org/ International Conference on Harmonisation]
* [http://www.usp.org US Pharmacopeia]
* [http://www.iuphar.org International Union of Basic and Clinical Pharmacology]
* [http://www.iuphar-db.org IUPHAR Committee on Receptor Nomenclature and Drug Classification]
* [http://www.guidetopharmacology.org/ IUPHAR/BPS Guide to Pharmacology]

== Further reading ==
* {{cite book |doi=10.1201/9781420052558 |title=Textbook of Receptor Pharmacology |date=2010 |isbn=978-0-429-14730-2 |editor-last1=Foreman |editor-last2=Johansen |editor-last3=Gibb |editor-first1=John C. |editor-first2=Torben |editor-first3=Alasdair J. }}
* {{cite book|title=[[Goodman and Gilman's The Pharmacological Basis of Therapeutics]] |edition=12 |year=2011|first1=Laurence |last1=Brunton |editor1-last=Brunton |editor1-first=L. L. |editor2-last=Chabner |editor2-first=Bruce |editor3-last=Knollmann |editor3-first=Björn C. | name-list-style = vanc |isbn=978-0-07-162442-8|location=New York |publisher=McGraw-Hill }}
* {{cite book|title=Lippincott Illustrated Reviews: Pharmacology|first1=Karen|last1=Whalen| name-list-style = vanc |year=2014}}

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