Editing LSD (section)

===Pharmacokinetics===
The acute effects of LSD normally last between 6 and 12{{nbsp}}hours depending on dosage, tolerance, and age.<ref name="tihkal">{{cite book |vauthors=Shulgin A, Shulgin A |author-link1=Alexander Shulgin |author-link2=Ann Shulgin |chapter-url=http://www.erowid.org/library/books_online/tihkal/tihkal26.shtml |archive-date=15 October 2008 |archive-url=http://archive.wikiwix.com/cache/20081015082653/http://www.erowid.org/library/books_online/tihkal/tihkal26.shtml |chapter=LSD |title=[[TiHKAL]] |location=Berkeley, CA |publisher=Transform Press |date=1997 |isbn=0-9630096-9-9}}</ref><ref name="PassieHalpernStrichtenoth2008" /> Aghajanian and Bing (1964) found LSD had an elimination half-life of only 175&nbsp;minutes (about 3&nbsp;hours);<ref name="Aghajanian">{{cite journal |vauthors=Aghajanian GK, Bing OH |title=Persistence of lysergic acid diethylamide in the plasma of human subjects |journal=Clinical Pharmacology and Therapeutics |volume=5 |issue=5 |pages=611–614 |year=1964 |pmid=14209776 |doi=10.1002/cpt196455611| url=http://www.maps.org/w3pb/new/1964/1964_aghajanian_2224_1.pdf |s2cid=29438767 |archive-url= https://web.archive.org/web/20090327144227/http://www.maps.org/w3pb/new/1964/1964_aghajanian_2224_1.pdf |archive-date=March 27, 2009}}</ref> however, using more accurate techniques, Papac and Foltz (1990) reported that 1&nbsp;μg/kg oral LSD given to a single male volunteer had an apparent plasma half-life of 5.1&nbsp;hours, with a peak plasma concentration of 5&nbsp;ng/mL at 3&nbsp;hours post-dose.<ref name="Papac">{{cite journal |vauthors=Papac DI, Foltz RL |title=Measurement of lysergic acid diethylamide (LSD) in human plasma by gas chromatography/negative ion chemical ionization mass spectrometry |journal=Journal of Analytical Toxicology |volume=14 |issue=3 |pages=189–190 |date=May–June 1990 |pmid=2374410 |doi=10.1093/jat/14.3.189 |url=http://www.erowid.org/references/refs_view.php?A=ShowDocPartFrame&C=ref&ID=6265&DocPartID=6624 |url-status=live|format=PDF |archive-date=April 29, 2011|archive-url=https://web.archive.org/web/20110429060433/http://www.erowid.org/references/refs_view.php?A=ShowDocPartFrame&C=ref&ID=6265&DocPartID=6624}}</ref>

The [[pharmacokinetics]] of LSD were not properly determined until 2015, which is not surprising for a drug with the kind of low-μg potency that LSD possesses.<ref name=Dol2015 /><ref name=Muc2016 /> In a sample of 16 healthy subjects, a single mid-range 200&nbsp;μg oral dose of LSD was found to produce mean [[Cmax (pharmacology)|maximal concentration]]s of 4.5&nbsp;ng/mL at a median of 1.5&nbsp;hours (range 0.5–4&nbsp;hours) post-administration.<ref name=Dol2015 /><ref name=Muc2016 /> Concentrations of LSD decreased following [[first-order kinetics]] with a [[half-life]] of 3.6±0.9 hours and a [[terminal half-life]] of 8.9±5.9 hours.<ref name=Dol2015 /><ref name=Muc2016 />

The effects of the dose of LSD given lasted for up to 12&nbsp;hours and were closely correlated with the concentrations of LSD present in circulation over time, with no acute [[drug tolerance|tolerance]] observed.<ref name="Dol2015" /><ref name="Muc2016" /> Only 1% of the drug was eliminated in [[urine]] unchanged, whereas 13% was eliminated as the major [[metabolite]] 2-oxo-3-hydroxy-LSD (O-H-LSD) within 24&nbsp;hours.<ref name="Dol2015" /><ref name="Muc2016" /> O-H-LSD is formed by [[cytochrome P450]] [[enzyme]]s, although the specific enzymes involved are unknown, and it does not appear to be known whether O-H-LSD is pharmacologically active or not.<ref name="Dol2015" /><ref name="Muc2016" /> The oral [[bioavailability]] of LSD was crudely estimated as approximately 71% using previous data on [[intravenous]] administration of LSD.<ref name="Dol2015" /><ref name="Muc2016" /> The sample was equally divided between male and female subjects and there were no significant sex differences observed in the pharmacokinetics of LSD.<ref name="Dol2015" /><ref name="Muc2016" /> In a subsequent, higher-quality study, the oral bioavailability of LSD was about 80%.<ref name="Holze_2024">{{cite journal | vauthors = Holze F, Mueller L, Vizeli P, Luethi D, Rudin D, Hysek C, Liechti M, Arikci D | title = Oral LSD base and tartrate bioequivalence and absolute bioavailability in healthy participants | journal = Neuroscience Applied | volume = 3 | pages = 105132 | date = 2024 | doi = 10.1016/j.nsa.2024.105132 | doi-access = free }}</ref>

A large meal before taking LSD has been found to result in circulating levels that were 50% lower than on an empty stomach.<ref name="PassieHalpernStrichtenoth2008" />

It has been said that there is a peculiar 40-minute lag before [[onset of action|onset]] of the psychedelic effects of LSD when it is administered [[intravenous injection|intravenously]].<ref name="GumpperNichols2024" /> This has been said to be related to time-dependent interactions of LSD with the serotonin 5-HT<sub>2A</sub> receptor.<ref name="GumpperNichols2024" /> However, contradicting the preceding claims, other sources have stated that intravenous injection of LSD results in onset of effects within a few minutes.<ref name="PassieHalpernStrichtenoth2008" /><ref name="Shulgin1980b" /> In addition, [[intrathecal injection]] (intraspinal injection) is reported to have a virtually instantaneous onset of action.<ref name="PassieHalpernStrichtenoth2008" /><ref name="Shulgin1980b" /> Doses of LSD are said to be similar by oral and injectable routes, with the exception of intrathecal injection in which the dosage is reduced to about one-third of usual.<ref name="Shulgin1980b" />