Editing Route of administration (section)

===Oral===
The oral route is generally the most convenient and costs the least.<ref name="Nursing Times"/> However, some drugs can cause [[gastrointestinal tract]] irritation.<ref name=DDS>{{cite web |url= http://www.ct.gov/dds/lib/dds/edsupp/medadmin_recert_part_ii.pdf |title= DDS Medication Administration Recertification Manual |date= 2006 |work= DDS Recertification Review Manual |publisher= State of [[Connecticut Department of Developmental Services]] |access-date= April 2, 2013 |archive-url= https://web.archive.org/web/20130514074151/http://www.ct.gov/dds/lib/dds/edsupp/medadmin_recert_part_ii.pdf |archive-date= May 14, 2013 |url-status= live }}</ref> For drugs that come in [[delayed release (pharmacology)|delayed release]] or [[Time Release Capsule|time-release]] formulations, breaking the tablets or capsules can lead to more rapid delivery of the drug than intended.<ref name="Nursing Times"/> The oral route is limited to [[Formulation#Pharmacy|formulations]] containing [[small molecule]]s only while biopharmaceuticals (usually proteins) would be  digested in the stomach and thereby become ineffective. Biopharmaceuticals have to be given by injection or infusion. However, recent research found various ways to improve oral bioavailability of these drugs. In particular permeation enhancers,<ref>{{cite journal|last1= Yamamoto |first1=A|last2= Ukai |first2=H | last3= Morishita |first3=M| last4= Katsumi |first4=H | title= Approaches to improve intestinal and transmucosal absorption of peptide and protein drugs |journal= Adv Drug Deliv Rev |date=2020|volume=211|pages=107537 |doi=10.1016/j.pharmthera.2020.107537|pmid=32201316|s2cid=214618193}}</ref> [[ionic liquid]]s,<ref>{{Cite journal|last1=Banerjee|first1=Amrita|last2=Ibsen|first2=Kelly|last3=Brown|first3=Tyler|last4=Chen|first4=Renwei |last5=Agatemor|first5=Christian|last6=Mitragotri|first6=Samir|date=2018-06-20|title=Ionic liquids for oral insulin delivery|journal=Proceedings of the National Academy of Sciences|language=en|pages=7296–7301|doi=10.1073/pnas.1722338115|issn=0027-8424|pmid=29941553|pmc=6048483|volume=115|issue=28|bibcode=2018PNAS..115.7296B|doi-access=free}}</ref> lipid-based nanocarriers,<ref>{{cite journal|last1= Haddadzadegan |first1=S|last2= Dorkoosh |first2=F | last3=Bernkop-Schnürch|first3=A|title= Oral delivery of therapeutic peptides and proteins: Technology landscape of lipid-based nanocarriers |journal= Adv Drug Deliv Rev |date=2022|volume=182|pages=114097 |doi=10.1016/j.addr.2021.114097|pmid=34999121|doi-access=free}}</ref> enzyme inhibitors and microneedles<ref>{{cite journal|last1= Maher |first1=S|last2= Brayden|first2=DJ | title= Approaches to improve intestinal and transmucosal absorption of peptide and protein drugs |journal= Pharmacol Ther |date=2021| volume=177|pages=113925| doi=10.1016/j.addr.2021.113925|pmid=34418495|doi-access=free}}</ref> have shown potential.

[[Oral administration]] is often denoted "PO" from "per os", the Latin for "by mouth".

The bioavailability of oral administration is affected by the amount of drug that is absorbed across the [[intestinal epithelium]] and [[first-pass metabolism]].<ref name="Hebert 2013 pp. 17–39">{{cite book | last=Hebert | first=Mary F. | title=Clinical Pharmacology During Pregnancy | chapter=Impact of Pregnancy on Maternal Pharmacokinetics of Medications | publisher=Elsevier | year=2013 | isbn=978-0-12-386007-1 | doi=10.1016/b978-0-12-386007-1.00003-9 | pages=17–39}}</ref>