Editing Preclinical development (section)

==Animal testing==
The information collected from these studies is vital so that safe human testing can begin.  Typically, in drug development studies animal testing involves two species.  The most commonly used models are [[Murinae|murine]] and [[Dog|canine]], although [[macaque|primate]] and [[pig|porcine]] are also used.

===Choice of species===
The choice of species is based on which will give the best correlation to human trials.  Differences in the [[Gastrointestinal tract|gut]], [[enzyme activity]], [[circulatory system]], or other considerations make certain models more appropriate based on the [[dosage form]], site of activity, or noxious [[metabolites]].  For example, canines may not be good models for solid oral dosage forms because the characteristic carnivore intestine is underdeveloped compared to the omnivore's, and gastric emptying rates are increased.  Also, rodents can not act as models for antibiotic drugs because the resulting alteration to their intestinal flora causes significant [[Adverse effect (medicine)|adverse effects]].  Depending on a drug's functional groups, it may be metabolized in similar or different ways between species, which will affect both efficacy and toxicology.

Medical device studies also use this basic premise.  Most studies are performed in larger species such as dogs, pigs and sheep which allow for testing in a similar sized model as that of a human.  In addition, some species are used for similarity in specific organs or organ system physiology (swine for dermatological and coronary stent studies; goats for mammary implant studies; dogs for [[gastric]] and [[cancer]] studies; etc.).

Importantly, the regulatory guidelines of [[Food and Drug Administration|FDA]], [[European Medicines Agency|EMA]], and other similar international and regional authorities usually require safety testing in at least two mammalian species, including one non-rodent species, prior to human trials authorization.<ref name=pmid26281720>{{cite journal | vauthors = Atanasov AG, Waltenberger B, Pferschy-Wenzig EM, Linder T, Wawrosch C, Uhrin P, Temml V, Wang L, Schwaiger S, Heiss EH, Rollinger JM, Schuster D, Breuss JM, Bochkov V, Mihovilovic MD, Kopp B, Bauer R, Dirsch VM, Stuppner H | title = Discovery and resupply of pharmacologically active plant-derived natural products: A review | journal = Biotechnology Advances | volume = 33 | issue = 8 | pages = 1582–1614 | date = December 2015 | pmid = 26281720 | pmc = 4748402 | doi = 10.1016/j.biotechadv.2015.08.001 }}</ref>

===Ethical issues===
[[Animal testing]] in the research-based pharmaceutical industry has been reduced in recent years both for ethical and cost reasons.  However, most research will still involve animal based testing for the need of similarity in anatomy and physiology that is required for diverse product development.