Editing Naloxone (section)

===Pharmacokinetics===
When administered [[wikt:parenteral|parenterally]] (non-orally or non-rectally, e.g., intravenously or by injection), as is most common, naloxone has a rapid distribution throughout the body. The mean serum half-life has been shown to range from 30 to 81 minutes, shorter than the average half-life of some opiates, necessitating repeat dosing if opioid receptors must be stopped from triggering for an extended period. Naloxone is primarily metabolized by the liver. Its major metabolite is naloxone-3-glucuronide, which is excreted in the urine.<ref name="DailyMed"/> For people with liver diseases such as [[alcoholic liver disease]] or [[hepatitis]], naloxone usage has not been shown to increase serum liver enzyme levels.<ref>{{Citation|title=Naloxone|date=2012|url=http://www.ncbi.nlm.nih.gov/books/NBK548244/|work=LiverTox: Clinical and Research Information on Drug-Induced Liver Injury|publisher=National Institute of Diabetes and Digestive and Kidney Diseases|pmid=31643568|access-date=30 October 2019|archive-date=28 August 2021|archive-url=https://web.archive.org/web/20210828181317/https://www.ncbi.nlm.nih.gov/books/NBK548244/|url-status=live}}</ref>

Naloxone has low systemic bioavailability when [[Oral administration|taken by mouth]] due to hepatic first-pass metabolism, but it does block opioid receptors that are located in the intestine.<ref name="pmid10601678">{{cite journal | vauthors = Meissner W, Schmidt U, Hartmann M, Kath R, Reinhart K | title = Oral naloxone reverses opioid-associated constipation | journal = Pain | volume = 84 | issue = 1 | pages = 105–109 | date = January 2000 | pmid = 10601678 | doi = 10.1016/S0304-3959(99)00185-2 | s2cid = 42230143 }}</ref>