Fire: Created page with "{{Short description|Time taken for a drug to halve its concentration in blood plasma}} {{use dmy dates |date=August 2021}} '''Biological half-life''' ('''elimination half-life''', '''pharmacological half-life''') is the time taken for concentration of a biological substance (such as a medication) to decrease from its maximum concentration (C_max) to half of C_max in the blood plasma..."

2023-11-15T03:12:55Z

Created page with "{{Short description|Time taken for a drug to halve its concentration in blood plasma}} {{use dmy dates |date=August 2021}} '''Biological half-life''' ('''elimination half-life''', '''pharmacological half-life''') is the time taken for concentration of a biological substance (such as a medication) to decrease from its maximum concentration (Cmax) to half of Cmax in the blood plasma..."

New page

{{Short description|Time taken for a drug to halve its concentration in blood plasma}}
{{use dmy dates |date=August 2021}}

'''Biological half-life''' ('''elimination half-life''', '''pharmacological half-life''') is the time taken for concentration of a [[drug|biological substance]] (such as a [[medication]]) to decrease from its maximum [[concentration (chemistry)|concentration]] ([[Cmax (pharmacology)|Cmax]]) to half of Cmax in the [[blood plasma]].<ref>{{Cite web |url=https://sites.google.com/site/pharmacologyinonesemester/2-drug-distribution-metabolism-and-elimination/2-5-blood-levels/2-5-2-elimination-half-life |title=Elimination Half-Life |website=Pharmacology in one semester |access-date=20 February 2020 |archive-date=22 October 2020 |archive-url=https://web.archive.org/web/20201022081736/https://sites.google.com/site/pharmacologyinonesemester/2-drug-distribution-metabolism-and-elimination/2-5-blood-levels/2-5-2-elimination-half-life |url-status=dead }}</ref><ref name="AIDSinfo 2020">{{cite web | title=Definition of Half-Life (t½) | website=AIDSinfo | date=2020-02-19 | url=https://aidsinfo.nih.gov/understanding-hiv-aids/glossary/286/half-life | access-date=2020-02-20 | archive-date=20 February 2020 | archive-url=https://web.archive.org/web/20200220040435/https://aidsinfo.nih.gov/understanding-hiv-aids/glossary/286/half-life | url-status=dead }}</ref><ref name="Curry 1993 pp. 127–144">{{cite book | last=Curry | first=Stephen H. | title=Antipsychotic Drugs and their Side-Effects | chapter=PHARMACOKINETICS OF ANTIPSYCHOTIC DRUGS | publisher=Elsevier | year=1993 | isbn=978-0-12-079035-7 | doi=10.1016/b978-0-12-079035-7.50015-4 | pages=127–144 | quote=The elimination half-life measures the kinetics of loss of drug from the body as a whole once all distribution equilibria have been achieved.}}</ref><ref name="Dasgupta Krasowski 2020 pp. 1–17">{{cite book | last1=Dasgupta | first1=Amitava | last2=Krasowski | first2=Matthew D. | title=Therapeutic Drug Monitoring Data | chapter=Pharmacokinetics and therapeutic drug monitoring | publisher=Elsevier | year=2020 | isbn=978-0-12-815849-4 | doi=10.1016/b978-0-12-815849-4.00001-3 | pages=1–17 | s2cid=209258489 | quote=The half-life of a drug is the time required for the serum concentration to be reduced by 50%. Once the half-life of the drug is known, the time required for clearance can be estimated. Approximately 97% of the drug is eliminated by 5 halflives, while ~99% is eliminated by 7 half-lives. }}</ref><ref>{{cite journal | journal= Journal of Veterinary Pharmacology and Therapeutics| volume=27 | issue=6 | pages=427–439 | date=2004 | quote=Following i.v. administration, the terminal half-life is the time required for plasma/blood concentration to decrease by 50% after pseudo-equilibrium of distribution has been reached; then, terminal half-life is computed when the decrease in drug plasma concentration is due only to drug elimination, and the term ‘elimination half-life’ is applicable. Therefore, it is not the time necessary for the amount of the administered drug to fall by one half.| doi=10.1111/j.1365-2885.2004.00600.x | pmid=15601438 | title=Plasma terminal half-life | last1=Toutain | first1=P. L. | last2=Bousquet-Melou | first2=A. | archive-url=https://web.archive.org/web/20200220042629/http://physiologie.envt.fr/wp-content/uploads/2016/06/Plasma_terminal_half-life.pdf |url=http://physiologie.envt.fr/wp-content/uploads/2016/06/Plasma_terminal_half-life.pdf| archive-date=2020-02-20 }}</ref> It is denoted by the abbreviation '''<math>t_{\frac{1}{2}}</math>'''.<ref name="AIDSinfo 2020"/><ref name="Dasgupta Krasowski 2020 pp. 1–17"/>

This is used to measure the removal of things such as [[metabolite]]s, [[drug]]s, and [[signalling molecule]]s from the body. Typically, the biological half-life refers to the body's natural [[detoxification]] (cleansing) through [[liver metabolism]] and through the [[excretion]] of the measured substance through the kidneys and intestines. This concept is used when the rate of removal is roughly [[Exponential function|exponential]].<ref>{{GoldBookRef|title=Biological Half Life|file=B00658}}</ref>

In a medical context, half-life explicitly describes the time it takes for the [[blood plasma]] concentration of a substance to halve (''plasma half-life'') its steady-state when circulating in the full blood of an [[organism]]. This measurement is useful in medicine, [[pharmacology]] and [[pharmacokinetics]] because it helps determine how much of a drug needs to be taken and how frequently it needs to be taken if a certain average amount is needed constantly. By contrast, the stability of a substance in plasma is described as ''plasma stability.'' This is essential to ensure accurate analysis of drugs in plasma and for [[drug discovery]].

The relationship between the biological and plasma half-lives of a substance can be complex depending on the substance in question, due to factors including accumulation in tissues, [[Plasma protein binding|protein binding]], active metabolites, and receptor interactions.<ref name="SCM">{{cite book|title=Spinal Cord Medicine|author1=Lin VW|author2=Cardenas DD|publisher=Demos Medical Publishing, LLC|page=251|url=https://books.google.com/books?id=3anl3G4No_oC&pg=PA251|year=2003|isbn=1-888799-61-7}}</ref>

==Examples==

===Water===
The biological half-life of water in a human is about 7 to 14 days. It can be altered by behavior. Drinking large amounts of [[alcohol (drug)|alcohol]] will reduce the biological half-life of water in the body.<ref name="isbn0-12-369413-2">{{cite book | author = Nordberg, Gunnar | title = Handbook on the toxicology of metals | publisher = Elsevier | location = Amsterdam | year = 2007 | pages =119 | isbn = 978-0-12-369413-3 }}</ref><ref name="isbn0-521-84228-X">{{cite book |author1=Silk, Kenneth R. |author2=Tyrer, Peter J. | title = Cambridge textbook of effective treatments in psychiatry | publisher = Cambridge University Press | location = Cambridge, UK | year = 2008 | pages = 295 | isbn = 978-0-521-84228-0 }}</ref> This has been used to decontaminate patients who are internally contaminated with [[tritiated water]]. The basis of this decontamination method is to increase the rate at which the water in the body is replaced with new water.

=== Alcohol ===
The removal of [[ethanol]] (drinking alcohol) through oxidation by [[alcohol dehydrogenase]] in the [[liver]] from the human body is limited. Hence the removal of a large concentration of alcohol from [[blood]] may follow [[Rate equation#Zero order|zero-order kinetics]]. Also the rate-limiting steps for one substance may be in common with other substances. For instance, the blood alcohol concentration can be used to modify the biochemistry of [[methanol]] and [[ethylene glycol]]. In this way the oxidation of methanol to the [[toxic]] [[formaldehyde]] and [[formic acid]] in the human body can be prevented by giving an appropriate amount of [[ethanol]] to a person who has [[eating|ingested]] methanol. Methanol is very toxic and causes [[blindness]] and death. A person who has ingested [[ethylene glycol]] can be treated in the same way. Half life is also relative to the subjective metabolic rate of the individual in question.

=== Common prescription medications ===

{| class="wikitable"
!Substance!!Biological half-life
|-
|[[Adenosine]]||Less than 10 seconds (estimate)<ref>{{cite book|title=Austria-Codex| veditors = Haberfeld H |at=Adenosin Baxter3 mg/ml Injektionslösung|publisher=Österreichischer Apothekerverlag|location=Vienna|year=2020|language=German}}</ref>
|-
|[[Norepinephrine (drug)|Norepinephrine]]||2 minutes<ref>{{cite book|title=Austria-Codex| veditors = Haberfeld H |at=Noradrenalin Orpha 1 mg/ml Konzentrat zur Herstellung einer Infusionslösung|publisher=Österreichischer Apothekerverlag|location=Vienna|year=2020|language=German}}</ref>
|-
|[[Oxaliplatin]]||14 minutes<ref>{{cite journal |last=Ehrsson |first=Hans |url=http://journals.humanapress.com/index.php?option=com_opbookdetails&task=articledetails&category=humanajournals&article_code=MO:19:4:261 |title=Pharmacokinetics of oxaliplatin in humans |journal=Medical Oncology |volume=19 |issue=4 |pages=261–5 |date=Winter 2002 |access-date=2007-03-28 |display-authors=etal |url-status=dead |archive-url=https://web.archive.org/web/20070928104657/http://journals.humanapress.com/index.php?option=com_opbookdetails&task=articledetails&category=humanajournals&article_code=MO%3A19%3A4%3A261 |archive-date=2007-09-28 |pmid=12512920 |doi=10.1385/MO:19:4:261 |s2cid=1068099 }}</ref>
|-
|[[Zaleplon]]||1 hour<ref>Zaleplon {{Drugs.com|monograph|zaleplon}}. Accessed 15 April 2021.</ref>
|-
|[[Morphine]]||1.5–4.5 hours<ref>Morphine {{Drugs.com|monograph|morphine}}. Accessed 15 April 2021.</ref>
|-
|[[Flurazepam]]
|2.3 hours<ref name="flurazepam">Flurazepam {{Drugs.com|monograph|flurazepam}}. Accessed 15 April 2021.</ref>
Active metabolite ([[N-desalkylflurazepam]]): 47–100 hours<ref name="flurazepam" />
|-
|[[Methotrexate]]||3–10 hours (lower doses),
8–15 hours (higher doses)<ref>{{cite web|url=http://reference.medscape.com/drug/trexall-methotrexate-343201#showall|title=Trexall, Otrexup (methotrexate) dosing, indications, interactions, adverse effects, and more|website=reference.medscape.com}}</ref>
|-
|[[Methadone]]||15–72 hours
in rare cases up to 8 days<ref>{{cite journal |last=Manfredonia |first=John |url=http://www.jaoa.org/cgi/content/full/105/3_suppl/18S |title=Prescribing Methadone for Pain Management in End-of-Life Care |journal=Journal of the American Osteopathic Association |volume=105 |date=March 2005 |issue=3 supplement |pages=S18-21 |access-date=2007-01-29 |pmid=18154194 |archive-date=20 May 2007 |archive-url=https://web.archive.org/web/20070520062222/http://www.jaoa.org/cgi/content/full/105/3_suppl/18S |url-status=dead }}</ref>
|-
|[[Diazepam]]||20–50 hours<ref name="diazepam">Diazepam {{Drugs.com|monograph|diazepam}}. Accessed 15 April 2021.</ref>
Active metabolite ([[nordazepam]]): 30–200 hours<ref name="diazepam" />
|-
|[[Phenytoin]]||20–60 hours<ref>{{cite book|title=Austria-Codex| veditors = Haberfeld H |at=Epilan D 100 mg-Tabletten|publisher=Österreichischer Apothekerverlag|location=Vienna|year=2020|language=German}}</ref>
|-
|[[Buprenorphine]]||28–35 hours<ref>Buprenorphine {{Drugs.com|monograph|buprenorphine}}. Accessed 15 April 2021.</ref>
|-
|[[Clonazepam]]||30–40 hours<ref>{{cite web |url=https://www.gene.com/download/pdf/klonopin_prescribing.pdf |title=Klonopin (clonazepam) Prescribing Guide |date=October 2017 |publisher=Genetech USA, Inc. |access-date=2019-01-20}}</ref>
|-
|[[Donepezil]]||3 days (70 hours)<ref name="Asiri Mostafa 2010 pp. 117–150">{{cite book | last1=Asiri | first1=Yousif A. | last2=Mostafa | first2=Gamal A.E. | title=Profiles of Drug Substances, Excipients and Related Methodology | volume=35 | chapter=Donepezil | publisher=Elsevier | year=2010 | isbn=978-0-12-380884-4 | issn=1871-5125 | doi=10.1016/s1871-5125(10)35003-5 | pmid=22469221 | pages=117–150 | quote=Plasma donepezil concentrations decline with a half-life of approximately 70 h. Sex, race, and smoking history have no clinically significant influence on plasma concentrations of donepezil [46–51].}}</ref>
|-
|[[Fluoxetine]]||4–6 days (under continuous administration)<ref name="fluoxetine">Fluoxetine {{Drugs.com|monograph|fluoxetine}}. Accessed 15 April 2021.</ref>
Active lipophilic metabolite ([[norfluoxetine]]): 4–16 days<ref name="fluoxetine" />
|-
|[[Amiodarone]]
|14–107 days<ref>{{cite book|title=Austria-Codex| veditors = Haberfeld H |at=Sedacoron 200 mg-Tabletten|publisher=Österreichischer Apothekerverlag|location=Vienna|year=2020|language=German}}</ref>
|-
|[[Vandetanib]]||19 days<ref>{{cite web |title=Caprelsa (vandetanib) Tablets, for Oral Use. Full Prescribing Information |url=http://www.caprelsa.com/files/caprelsa-pi.pdf |publisher=Sanofi Genzyme, Cambridge, MA, Dec 2016. |access-date=24 February 2020}}</ref>
|-
|[[Dutasteride]]||21–35 days (under continuous administration)<ref>{{cite book|title=Austria-Codex| veditors = Haberfeld H |at=Avodart 0,5 mg Weichkapseln|publisher=Österreichischer Apothekerverlag|location=Vienna|year=2020|language=German}}</ref>
|-
|[[Bedaquiline]]||165 days<ref>{{cite web |title=Sirturo (bedaquiline) Tablets. Full Prescribing Information |url=https://www.accessdata.fda.gov/drugsatfda_docs/label/2012/204384s000lbl.pdf |publisher=Janssen Products, Dec 2012. |access-date=24 February 2020}}</ref>
|}

=== Metals ===
The biological half-life of [[caesium]] in humans is between one and four months. This can be shortened by feeding the person [[prussian blue]]. The prussian blue in the digestive system acts as a solid [[ion exchange]]r which absorbs the caesium while releasing [[potassium]] ions.

For some substances, it is important to think of the human or animal body as being made up of several parts, each with their own affinity for the substance, and each part with a different biological half-life ([[physiologically-based pharmacokinetic modelling]]). Attempts to remove a substance from the whole organism may have the effect of increasing the burden present in one part of the organism. For instance, if a person who is contaminated with lead is given [[EDTA]] in a [[chelation therapy]], then while the rate at which lead is lost from the body will be increased, the lead within the body tends to relocate into the [[brain]] where it can do the most harm.<ref>{{cite journal|title=Lead toxicity update. A brief review.|author1=Nikolas C Papanikolaou |author2=Eleftheria G Hatzidaki |author3=Stamatis Belivanis |author4=George N Tzanakakis |author5=Aristidis M Tsatsakis |journal=Medical Science Monitor|year=2005|volume=11|issue=10|pages=RA329-36 |url=http://www.medscimonit.com/abstract/index/idArt/430340|pmid=16192916 }}</ref>
*[[Polonium]] in the body has a biological [[half-life]] of about 30 to 50 days.
*[[Caesium]] in the body has a biological half-life of about one to four months.
*[[Mercury (element)|Mercury]] (as [[methylmercury]]) in the body has a half-life of about 65 days.
*Lead in the blood has a half life of 28–36 days.<ref>Griffin et al. 1975 as cited in ATSDR 2005</ref><ref>Rabinowitz et al. 1976 as cited in ATSDR 2005</ref>
*[[Lead]] in [[bone]] has a biological half-life of about ten years.
*[[Cadmium]] in bone has a biological half-life of about 30 years.
*[[Plutonium]] in bone has a biological half-life of about 100 years.
*[[Plutonium]] in the liver has a biological half-life of about 40 years.

=== Peripheral half-life ===
Some substances may have different half-lives in different parts of the body. For example, [[oxytocin]] has a [[half-life]] of typically about three minutes in the blood when given [[Intravenous therapy|intravenously]]. Peripherally administered (e.g. intravenous) peptides like oxytocin cross the [[blood-brain-barrier]] very poorly, although very small amounts (< 1%) do appear to enter the [[central nervous system]] in humans when given via this route.<ref name="BaribeauAnagnostou2015">{{cite journal |last1=Baribeau |first1=Danielle A |last2=Anagnostou |first2=Evdokia |title=Oxytocin and vasopressin: linking pituitary neuropeptides and their receptors to social neurocircuits |journal=Frontiers in Neuroscience |volume=9 |pages=335 |year=2015 |issn=1662-453X |doi=10.3389/fnins.2015.00335 |pmid=26441508 |pmc=4585313|doi-access=free }}</ref> In contrast to peripheral administration, when administered [[intranasal administration|intranasally]] via a nasal spray, oxytocin reliably crosses the [[blood–brain barrier]] and exhibits [[psychoactive]] effects in humans.<ref name="Oxy BBB">{{cite book |vauthors=Malenka RC, Nestler EJ, Hyman SE |veditors=Sydor A, Brown RY |title=Molecular Neuropharmacology: A Foundation for Clinical Neuroscience |year=2009 |publisher=McGraw-Hill Medical |location=New York |isbn=9780071481274 |page=195 |edition=2nd |chapter=Chapter 7: Neuropeptides |quote=Oxytocin can be delivered to humans via nasal spray following which it crosses the blood–brain barrier. ... In a double-blind experiment, oxytocin spray increased trusting behavior compared to a placebo spray in a monetary game with real money at stake.}}</ref><ref name="Oxytocinergic circuit">{{cite journal |vauthors=McGregor IS, Callaghan PD, Hunt GE |title=From ultrasocial to antisocial: a role for oxytocin in the acute reinforcing effects and long-term adverse consequences of drug use? |journal=British Journal of Pharmacology |volume=154 |issue=2 |pages=358–68 |date=May 2008 |pmid=18475254 |pmc=2442436 |doi=10.1038/bjp.2008.132 |quote = Recent studies also highlight remarkable anxiolytic and prosocial effects of intranasally administered OT in humans, including increased ‘trust’, decreased amygdala activation towards fear-inducing stimuli, improved recognition of social cues and increased gaze directed towards the eye regions of others (Kirsch et al., 2005; Kosfeld et al., 2005; Domes et al., 2006; Guastella et al., 2008)}}</ref> In addition, also unlike the case of peripheral administration, intranasal oxytocin has a central duration of at least 2.25 hours and as long as 4 hours.<ref name="Weisman 2012">{{cite journal |vauthors=Weisman O, Zagoory-Sharon O, Feldman R |title=Intranasal oxytocin administration is reflected in human saliva |journal=[[Psychoneuroendocrinology (journal)|Psychoneuroendocrinology]] |volume=37 |issue=9 |pages=1582–6 |year=2012 |pmid=22436536 |doi=10.1016/j.psyneuen.2012.02.014 |s2cid=25253083 }}</ref><ref name="Huffmeijer 2012">{{cite journal |vauthors=Huffmeijer R, Alink LR, Tops M, Grewen KM, Light KC, Bakermans-Kranenburg MJ, Ijzendoorn MH |title=Salivary levels of oxytocin remain elevated for more than two hours after intranasal oxytocin administration |journal=[[Neuro Endocrinology Letters]] |volume=33 |issue=1 |pages=21–5 |year=2012 |pmid=22467107}}</ref> In likely relation to this fact, endogenous oxytocin concentrations in the brain have been found to be as much as 1000-fold higher than peripheral levels.<ref name="BaribeauAnagnostou2015" />

==Rate equations==
{{Main|Rate equation}}
{{See also|Pharmacokinetics#Metrics}}

===First-order elimination===
{| class="wikitable floatright"
|+ Timeline of an exponential decay process<ref name="HackerMesser2009">{{cite book|author1=Miles Hacker|author2=William S. Messer|author3=Kenneth A. Bachmann|title=Pharmacology: Principles and Practice|url=https://books.google.com/books?id=5YDMmjWXe-AC&pg=PA255|date=19 June 2009|publisher=Academic Press|isbn=978-0-08-091922-5|page=205}}</ref><ref name="Frymoyer2019">{{cite book|last1=Frymoyer|first1=Adam|title=Infectious Disease and Pharmacology|chapter=Pharmacokinetic Considerations in Neonates|year=2019|pages=123–139|doi=10.1016/B978-0-323-54391-0.00011-4|isbn=9780323543910|s2cid=57512164 }}</ref><ref name="ChanUchizono2015">{{cite book|last1=Chan|first1=Patrick|last2=Uchizono|first2=James A.|title=Essentials of Pharmacology for Anesthesia, Pain Medicine, and Critical Care|chapter=Pharmacokinetics and Pharmacodynamics of Anesthetics|year=2015|pages=3–47|doi=10.1007/978-1-4614-8948-1_1|isbn=978-1-4614-8947-4}}</ref>
|-
! Time (t) !! Percent of initial value !! Percent completion
|-
| t½ || 50% || 50%
|-
| t½ × 2 || 25% || 75%
|-
| t½ × 3 || 12.5% || 87.5%
|-
| t½ × 3.322 || 10.00% || 90.00%
|-
| t½ × 4 || 6.25% || 93.75%
|-
| t½ × 4.322 || 5.00% || 95.00%
|-
| t½ × 5 || 3.125% || 96.875%
|-
| t½ × 6 || 1.5625% || 98.4375%
|-
| t½ × 7 || 0.78125% || 99.21875%
|-
| t½ × 10 || ~0.09766% || ~99.90234%
|-
|}

Half-times apply to processes where the elimination rate is exponential. If <math>C(t)</math> is the concentration of a substance at time <math>t</math>, its time dependence is given by

:<math>C(t) = C(0) e^{-kt} \,</math>

where ''k'' is the [[reaction rate constant]]. Such a decay rate arises from a [[Rate equation#First order|first-order reaction]] where the rate of elimination is proportional to the amount of the substance:<ref name=Bonate>{{cite book|last1=Bonate|first1=Peter L.|last2=Howard|first2=Danny R.|title=Clinical study design and analysis|date=2004|publisher=AAPS Press|location=Arlington, VA|isbn=9780971176744|pages=237–239}}</ref>
:<math>\frac{d C}{d t} = -k C.</math>

The half-life for this process is<ref name=Bonate/>

:<math>t_\frac{1}{2} = \frac{\ln 2}{k}. \,</math>

Alternatively, half-life is given by

:<math>t_\frac{1}{2} = \frac{\ln 2}{\lambda _{z}} \,</math>

where ''λz'' is the slope of the terminal phase of the time–concentration curve for the substance on a semilogarithmic scale.<ref name="ToutainBousquet-Melou2004">{{cite journal|last1=Toutain|first1=P. L.|last2=Bousquet-Melou|first2=A.|title=Plasma terminal half-life|journal=Journal of Veterinary Pharmacology and Therapeutics|volume=27|issue=6|year=2004|pages=427–439|issn=0140-7783|doi=10.1111/j.1365-2885.2004.00600.x|pmid=15601438}}</ref><ref name="Kwon2007">{{cite book|author=Younggil Kwon|title=Handbook of Essential Pharmacokinetics, Pharmacodynamics and Drug Metabolism for Industrial Scientists|url=https://books.google.com/books?id=yt7pBwAAQBAJ&pg=PA24|date=8 May 2007|publisher=Springer Science & Business Media|isbn=978-0-306-46820-9|pages=24–}}</ref>

Half-life is determined by [[Clearance (medicine)|clearance]] (CL) and [[volume of distribution]] (VD) and the relationship is described by the following equation:

:<math>t_\frac{1}{2} = \frac{{\ln 2}\cdot{V_D}}{CL} \,</math>

In clinical practice, this means that it takes 4 to 5 times the half-life for a drug's serum concentration to reach steady state after regular dosing is started, stopped, or the dose changed. So, for example, digoxin has a half-life (or t½) of 24–36 h; this means that a change in the dose will take the best part of a week to take full effect. For this reason, drugs with a long half-life (e.g., [[amiodarone]], elimination t½ of about 58 days) are usually started with a [[loading dose]] to achieve their desired clinical effect more quickly.

===Biphasic half-life===
Many drugs follow a biphasic elimination curve — first a steep slope then a shallow slope:
:STEEP (initial) part of curve —> initial distribution of the drug in the body.
:SHALLOW part of curve —> ultimate excretion of drug, which is dependent on the release of the drug from tissue compartments into the blood.
The longer half-life is called the ''terminal half-life'' and the half-life of the largest component is called the ''dominant half-life.''<ref name=Bonate/> For a more detailed description see [[Pharmacokinetics#Multi-compartmental models|Pharmacokinetics § Multi-compartmental models]].

==See also==
*[[Half-life]], pertaining to the general mathematical concept in physics or pharmacology.
*[[Effective half-life]]

==References==
{{Reflist|30em}}

{{Pharmacology}}
{{二次利用|date=31 October 2023}}
[[Category:Pharmacokinetics]]
[[Category:Mathematics in medicine]]
[[Category:Temporal exponentials]]

Biological half-life - Revision history