Editing First pass effect (section)

== Factors ==
First-pass metabolism may occur in the liver (for propranolol, lidocaine, [[clomethiazole]], and nitroglycerin) or in the gut (for [[benzylpenicillin]] and [[insulin]]).<ref>{{cite web|title=Understanding First Pass Metabolism|publisher=University of Nottingham|author=Bath-Hextall, Fiona|date=October 16, 2013|access-date=October 26, 2017|url=http://www.nottingham.ac.uk/nmp/sonet/rlos/bioproc/metabolism/01.html|archive-date=July 28, 2021|archive-url=https://web.archive.org/web/20210728110801/https://www.nottingham.ac.uk/nmp/sonet/rlos/bioproc/metabolism/01.html|url-status=live}}</ref> The four primary systems that affect the first pass effect of a drug are the [[enzyme]]s of the [[Gastrointestinal tract|gastrointestinal]] [[Lumen (anatomy)|lumen]],<ref name=":0">{{Cite journal |last1=Ilett |first1=Kenneth F. |last2=Tee |first2=Lisa B. G. |last3=Reeves |first3=Philip T. |last4=Minchin |first4=Rodney F. |date=1990-01-01 |title=Mebolism of drugs and other xenobiotics in the gut lumen and wall |url=https://linkinghub.elsevier.com/retrieve/pii/0163725890900362 |journal=Pharmacology & Therapeutics |volume=46 |issue=1 |pages=67–93 |doi=10.1016/0163-7258(90)90036-2 |issn=0163-7258|url-access=subscription }}</ref> gastrointestinal wall enzymes,<ref name=":1">{{Cite journal |last1=Thummel |first1=Kenneth E. |last2=Kunze |first2=Kent L. |last3=Shen |first3=Danny D. |date=1997-09-15 |title=Enzyme-catalyzed processes of first-pass hepatic and intestinal drug extraction |url=https://linkinghub.elsevier.com/retrieve/pii/S0169409X97000392 |journal=Advanced Drug Delivery Reviews |series=First-pass Metabolism and Its Impact on Oral Drug Delivery |volume=27 |issue=2 |pages=99–127 |doi=10.1016/S0169-409X(97)00039-2 |pmid=10837554 |issn=0169-409X|url-access=subscription }}</ref><ref name=":2">{{Cite journal |last1=Drozdzik |first1=Marek |last2=Busch |first2=Diana |last3=Lapczuk |first3=Joanna |last4=Müller |first4=Janett |last5=Ostrowski |first5=Marek |last6=Kurzawski |first6=Mateusz |last7=Oswald |first7=Stefan |date=2018 |title=Protein Abundance of Clinically Relevant Drug-Metabolizing Enzymes in the Human Liver and Intestine: A Comparative Analysis in Paired Tissue Specimens |url=https://ascpt.onlinelibrary.wiley.com/doi/10.1002/cpt.967 |journal=Clinical Pharmacology & Therapeutics |language=en |volume=104 |issue=3 |pages=515–524 |doi=10.1002/cpt.967 |pmid=29205295 |issn=1532-6535|url-access=subscription }}</ref><ref>{{Cite journal |last1=Doherty |first1=Margaret M. |last2=Charman |first2=William N. |date=2002-04-01 |title=The Mucosa of the Small Intestine |url=https://link.springer.com/article/10.2165/00003088-200241040-00001 |journal=Clinical Pharmacokinetics |language=en |volume=41 |issue=4 |pages=235–253 |doi=10.2165/00003088-200241040-00001 |pmid=11978143 |issn=1179-1926|url-access=subscription }}</ref> bacterial enzymes<ref name=":0" /> and hepatic enzymes.<ref name=":1" /><ref name=":2" /><ref>{{Cite journal |last1=Bramer |first1=S. L. |last2=Au |first2=J. L. |last3=Wientjes |first3=M. G. |date=1993 |title=Gastrointestinal and hepatic first-pass elimination of 2',3'-dideoxyinosine in rats |url=https://pubmed.ncbi.nlm.nih.gov/8496819/ |journal=The Journal of Pharmacology and Experimental Therapeutics |volume=265 |issue=2 |pages=731–738 |issn=0022-3565 |pmid=8496819}}</ref>