Editing Loperamide (section)

===Blood–brain barrier===
Efflux by P-glycoprotein also prevents circulating loperamide from effectively crossing the blood-brain barrier,<ref>{{cite journal | vauthors = Upton RN | title = Cerebral uptake of drugs in humans | journal = Clinical and Experimental Pharmacology & Physiology | volume = 34 | issue = 8 | pages = 695–701 | date = August 2007 | pmid = 17600543 | doi = 10.1111/j.1440-1681.2007.04649.x | s2cid = 41591261 }}</ref> so it can generally only agonize mu-opioid receptors in the [[peripheral nervous system]], and currently has a score of one on the anticholinergic cognitive burden scale.<ref>{{cite web |url=http://www.agingbraincare.org/uploads/products/ACB_scale_-_legal_size.pdf |title=Anticholinergic Cognitive Burden Scale |access-date=23 September 2017 |archive-url=https://web.archive.org/web/20180307142553/http://www.agingbraincare.org/uploads/products/ACB_scale_-_legal_size.pdf |archive-date=7 March 2018 |url-status=dead }}</ref> Concurrent administration of P-glycoprotein inhibitors such as [[quinidine]] potentially allows loperamide to cross the blood-brain barrier and produce central morphine-like effects. At high doses (>70mg), loperamide can saturate P-glycoprotein (thus overcoming the efflux) and produce euphoric effects.<ref>{{cite journal | vauthors = Antoniou T, Juurlink DN | title = Loperamide abuse | journal = CMAJ | volume = 189 | issue = 23 | pages = E803 | date = June 2017 | pmid = 28606977 | pmc = 5468105 | doi = 10.1503/cmaj.161421 }}</ref> Loperamide taken with quinidine was found to produce respiratory depression, indicative of central opioid action.<ref>{{cite journal | vauthors = Sadeque AJ, Wandel C, He H, Shah S, Wood AJ | title = Increased drug delivery to the brain by P-glycoprotein inhibition | journal = Clinical Pharmacology and Therapeutics | volume = 68 | issue = 3 | pages = 231–7 | date = September 2000 | pmid = 11014404 | doi = 10.1067/mcp.2000.109156 | s2cid = 38467170 }}</ref>

High doses of loperamide have been shown to cause a mild [[physical dependence]] during preclinical studies, specifically in mice, rats, and rhesus monkeys. Symptoms of mild opiate withdrawal were observed following abrupt discontinuation of long-term treatment of animals with loperamide.<ref>{{cite journal | vauthors = Yanagita T, Miyasato K, Sato J | title = Dependence potential of loperamide studied in rhesus monkeys | journal = NIDA Research Monograph | volume = 27 | pages = 106–13 | year = 1979 | pmid = 121326 }}</ref><ref>{{cite journal | vauthors = Nakamura H, Ishii K, Yokoyama Y, Motoyoshi S, Suzuki K, Sekine Y, Hashimoto M, Shimizu M | title = [Physical dependence on loperamide hydrochloride in mice and rats] | language = ja | journal = Yakugaku Zasshi | volume = 102 | issue = 11 | pages = 1074–85 | date = November 1982 | pmid = 6892112 | doi = 10.1248/yakushi1947.102.11_1074 | doi-access = free }}</ref>