Talk:Pharmacokinetics

message: This is an important topic that deserces an article of its own. However, copying the abstradt of a review article verbatim in Wikipedia is against the rules (copyright violation) and not useful, because these docoments are too long and too technical. The editor is welcome to write a short encyclopedic excerpt, taking into account other sources like WHO, NIH etc. Andreas 17:13, 9 January 2006 (UTC)
thread_title:  Drug-drug and drug-herbal interactions 

message: The constant which relates the exponent of decay (k) and half-life is easily determined by first principles from the equation for exponential decay. Mentioning circuit analysis seems totally crazy to me; no pharmacokineticist would know anything about circuits or ever need to. If this is important then I think that the maths only should be mentioned. ben 06:50, 23 May 2006 (UTC)
replies: text: You forget that biomedical engineers (which usually have some understanding of circuits) are involved in the design of medical devices, such as insulin pumps (which have ICs). Pharmacokinetics is not such a narrow field.  The research that lead to transdermal patches was done by a chemical engineer -- see Robert S. Langer. Nephron  T|C 20:24, 14 July 2006 (UTC)
thread_title:  One-compartment case 

message: Shouldn't there be something here about two (or more) compartment models, also non compartmental models?  Let me hasten to add, I'm not the person to write it ... Daen 15:22, 25 September 2006 (UTC)
replies: text: You are right. Just some remarks:The upper limit in practical use are three compartments, because the more compartments you add to your model, the more parameters you have to estimate from the data (two parameters for each compartment). Generally we have only samples from a limited number of compartments (plasma and urine – if we are lucky). Though it’s possible to get solutions from our curve fitting (i.e., nonlinear regression), the parameters are not identifiable for higher-order models any more. Not identifiable means that it is not possible to tell whether a given rate constant is attributable to a transfer process between two compartments, or elimination from the central compartment, e.t.c.Non compartmental models don’t exist (that’s a contradiction). The term used for example in bioequivalence testing is Non Compartmental Analysis (NCA). Parameters (or metrics) of NCA are e.g., the area under the curve AUC (calculated by some kind of numerical integration algorithm, mostly the trapezoidal rule), the peak concentration Cmax and the time point of its occurence tmax,… All these values are directly obtained from the data assuming no underlying PK model. --Alfie66 (talk) 00:41, 10 June 2008 (UTC)
thread_title:  Multicompartment models 

message: Variable volume pharmacokinetic models is now linked to this article. Linking back is a consideration, so is thinking about it. Talk to me. CarlWesolowski (talk) 14:20, 23 August 2016 (UTC)
replies: text: Variable volume pharmacokinetic models was deleted because of "contribution rules." Variable volume models were correctly stated as an alternative to compartmental modelling by S. Niazi "Volume of Distribution as a Function of Time" Journal of Pharmaceutical Sciences 1976 Vol. 65 Issue 3 Pages 452-454 https://doi.org/10.1002/jps.2600650339. This was later generalized to all PK models by C. A. Wesolowski (full disclosure, me) et al. "Time Varying Apparent Volume of Distribution and Drug Half-Lives Following Intravenous Bolus Injections" Plos One 2016, https://doi.org/10.1371/journal.pone.0158798, and applied in subsequent papers. Content contribution rules being somewhat arcane here, someone else would have to link these to the current article instead of the now dead link, or alternatively provide text once again to the now defunct "Variable volume pharmacokinetic models" link. With time, this may become increasingly important as alternative models are shown to work better than the same old stuff. CarlWesolowski (talk) 01:01, 17 November 2022 (UTC)
thread_title: Variable volume in time models

message: Who "invented" the "Pharmacokinetics"? —Preceding unsigned comment added by 217.86.119.8 (talk) 21:22, 3 October 2006 (UTC)
replies: text: Nobody – or like Newton 'invented' 'Gravity'… ;-)The term (:de:Pharmakokinetik) was first used in the 1950ies by the German Professor for Pediatrics Friedrich Hartmut Dost (*1910 †1985). I would translate the reference with “Blood level: Kinetics of the Course of Concentrations in the Systemic Circulation”.“Dost’s law of corresponding areas” (sometimes called Superposition Principle) describes the fact that in a linear pharmacokinetic system the area under the (plasma drug concentration-time) curve after a single dose (t=0-∞) equals to the AUC within a dosage interval (t=0-τ) in steady-state. -- Alfie (talk) 00:15, 10 June 2008 (UTC)
thread_title:  PK 

message: Would it be useful to have a list of the standard PK parameters, with some brief explanation? Examples: Cmax, Tmax, AUC, etc. —Preceding unsigned comment added by 216.158.41.81 (talk) 18:35, 27 June 2007 (UTC)
replies: text: Agree. Unfortunatelly I’m a little short in time… In the meantime have a look at a document published by the German ‘Association for Applied Human Pharmacology’ (AGAH). -- Alfie (talk) 00:50, 2 July 2008 (UTC)
replies: text:  I have made an initial effort at adding a Pharmacokinetics#Parameters section.  Thanks for the reference which I have added to the article. Cheers.  Boghog (talk) 16:15, 6 June 2010 (UTC)
thread_title:  Standard PK Parameters 

message: ===Drug properties that influence its pharmacokinetics===
Several drug properties can often influence the pharmacokinetics of many drugs.
===Organ partitioning===
 
====Partition coefficient====
The partition or distribution coefficient (KD) is the ratio of concentrations of a compound in the two phases of a mixture of two immiscible solvents at equilibrium. It can influence the ADME properties (Absorption, Distribution, Metabolism, and Excretion) of the drug. When orally administered drugs are absorbed they must first pass through lipid bilayers in the intestinal epithelium (a process known as transcellular transport). For efficient transport the drug must be hydrophobic enough to partition into the lipid bilayer but not so hydrophobic that once it is in the bilayer it will not partition out again. The partition coefficient is dependent on the hydrophobic or hydrophilic properties of the drug.
====Drug transporters====
Drug transporters are transmembrane proteins on the surface of cells and are responsible for facilitating or hindering the intracellular and paracellular transport of nutrients and other substances. Some known drug transporters include Breast Cancer Resistance Protein (BCRP, also known as ABCG2) and human intestinal peptide transporter (hPepT1). BCRP is a type of ATP-binding cassette transporter that can decrease the efficacy of chemotherapeutic agents in breast cancer by exporting agents out of the tumor cells, thus making them resistant to chemotherapy. Valacyclovir uses the hPepT1 transporter to increase the intestinal absorption of valacyclovir compared to acyclovir. Drug transporters can increase or decrease the absorption of drugs into the body as well as limit or facilitate the exposure of certain organs.
===Perfusion===
Perfusion or flow of blood to different organs, affects rate of presentation of drugs to different parts of the body and often affects the pharmacokinetics of many drugs. While the partition coefficient can affect the distribution of drugs from the blood stream to the organs, perfusion affects how fast a drug is presented to the organs. Different organs receive a vast supply of drugs while others receive minor amounts. For example, the kidneys receive vast quantities of blood, especially considering the relatively small size of the kidneys. Adipose tissue, on the other hand, receives a minor supply blood. Organs with a rich blood supply would be presented drug at a higher rate than organs with a lower blood supply.
Biophys (talk) 01:56, 5 September 2008 (UTC)
thread_title: Should this be placed back?

message: Perfusion or flow of blood to different organs, affects rate of presentation of drugs to different parts of the body and often affects the pharmacokinetics of many drugs. While the partition coefficient can affect the distribution of drugs from the blood stream to the organs, perfusion affects how fast a drug is presented to the organs. Different organs receive a vast supply of drugs while others receive minor amounts. For example, the kidneys receive vast quantities of blood, especially considering the relatively small size of the kidneys. Adipose tissue, on the other hand, receives a minor supply blood. Organs with a rich blood supply would be presented drug at a higher rate than organs with a lower blood supply.
Biophys (talk) 01:56, 5 September 2008 (UTC)
thread_title: Perfusion

message: Hello.
I am a member of WikiProject Pharmacology, a Wikipedia wide project that maintains and improves articles that fall under the scope of pharmacology. Since your article has fallen under our scope, I have placed the correct template(s) on this talk page for verification. Upon review of the article, I'd like to make a few points, as shown:
*Ressessed article with class and importance factors
*It was not a B-class article, yes, so it has been lowered to C. I also put this article for mid importance due to the fact that it is specifically taught in classes at multiple universities and required by state pharmacy boards, such as the South Dakota Board of Pharmacy.
I'm glad this article could fall within our scope, and I hope to see it grow large! Many thanks! Renaissancee (talk) 02:21, 3 June 2009 (UTC)
replies: text: I have changed pharmacology project importance rating from mid to top; along with pharmacodynamics, pharmacokinetics is a core pharmacology topic!  Boghog (talk) 16:24, 6 June 2010 (UTC)
thread_title: Article Reassessment for [[WP:PHARM|WikiProject Pharmacology]]

message: This article is quite poor to be in the English version of Wikipedia; I compared it with other versions like the spanish one, and I noticed there is an important lack of information here. An improvement of this article should be done. —Preceding unsigned comment added by 83.44.20.68 (talk • contribs) 01:20, 20 September 2009 (UTC)
replies: text: Please add new sections to talk pages at their bottom (I moved your contribution). Well, from a quick look at the Spanish version, I guess you are right. You are are cordially invited to start working on an adaption. —Alfie±Talk 13:08, 20 September 2009 (UTC)
thread_title:  Improvement of the article 

message: I have added a review of the development of the Plateau Principle in pharmacokinetics and the wide applicability of the mathematical model to other areas in biological sciences. It would be very helpful to obtain an expert review of this new entry.  Please provide comments in the talk section of Plateau Principleand delete this section when a review has been done.  Many thanks.  Jhargrov (talk) 14:03, 10 October 2009 (UTC)
replies: text: Hi James! Wow, you've done a lot of work! I will have a deeper look, time allowing (there are some minor flaws in the TEX-markup). To be honest, this term is rarely (whenever) used in pharmacokinetics - steady state is used instead. I cann't find the term in standard textbooks (like Dost 1953, Gibaldi/Perrier 1982, Wagner 1993, Gabrielsson/Weiner 2006) explaining the Superposition Principle. In German the term Plateauphase was used years ago, but was abandoned due to the sexual connotation (see Plateau phase); in German the English term 'steady state' is solely in use as a loanword for some time now. —Alfie±Talk 11:22, 12 October 2009 (UTC)
thread_title:  Request for review of [[Plateau Principle]] entry 

message: Under the "Simulation" subsection of the "Software" section it states: "All model based software above." Is that all of the software listed above, or certain members listed above? Aren't all of the names mentioned "model based"?   Could someone check on this? Maybe the statement should be: "Any of the software listed above." --74.179.120.70 (talk) 17:57, 13 September 2011 (UTC)
replies: text: Hi IP! I’m not a native speaker, maybe you can do better: Actually for simulation you can use any software except the ones in the first group (Noncompartmental ≡ not based on a PK model). Since I’m using a good part of them myself I’m routine-blinded. ;-) Alfie↑↓© 00:31, 14 September 2011 (UTC)
thread_title:  simulation software statement... 

message: Why does this article lead off with a graph of Michaelis Menten Kinetics?  Its a beautiful graph, but is not mentioned until the section on multi-compartment models.  I associate the MM curve more with biochemistry than pharmacokinetics, the latter having more to do with drug levels in vivo.  So as an introductory figure it kind of misses the point.  Additionally, its labeled in Spanish.  
This figure should be relabeled in English and moved to the middle portion of the article.   The 3rd figure (Farmacocinética_no_lineal.svg) should also be relabeled in English. 
I think a better introductory graph would be the IV time vs. concentration curve.  (Iv time conc curve.svg) 
mattelfesso (talk) 20:58, 29 April 2014 (UTC)
thread_title:  Michaelis Menten Kinetics 

message: The last paragraph of the Bioavailability section says "When two drugs have the same bioavailability, they are said to be biological equivalents or bioequivalents. This concept of bioequivalence is important because it is currently used as a yardstick in the authorization of generic drugs in many countries." 
This makes it sound like the article is saying bioavailability (BA) and bioequivalence (BE) are the same thing, which is not true. I'm guessing it's trying to say that BA contributes to BE. I don't feel confident enough to edit this sentence (I know the basics, but really just the basics), but I'm hoping someone with more knowledge that me can. Thank you to anyone who can help.  — Preceding unsigned comment added by 70.62.125.212 (talk) 15:58, 7 August 2014 (UTC)
replies: text: Your comments are spot on. An accurate definition of bioequivalence is found here that makes clear that bioequivalence depends not only on bioavailability as measured as area under the curve,  but also on Cmax. Bioavailability relates to the fraction of drug absorbed after oral administration and is estimated from ratio of area under the curve after oral vs. intravenous administration.  Bioequivalence in addition requires that the rate of absorption as measured by Cmax are similar. Boghog (talk) 19:24, 7 August 2014 (UTC)
replies: text: Hi IP and Boghog! AFAIK the FDA introduced the terms extent and rate of biovailability in the early 1980s, whereas the former is given by the AUC and the latter by Cmax. At that time the pharmacokinetic community protested, since according to all textbooks BA = AUC. Still many colleagues call the term  extent of BA plain nonsense. Since I’m not a native speaker of English any suggestions to change the paragraph are welcome. In an article about PK I would stick to the definition of BA as given in textbooks and make clear that the regulatory definition is different. Alfie↑↓© 14:09, 11 August 2014 (UTC)
thread_title:  Bioavailability section - re-wording of last paragraph of needed (so people don't think BA=BE) 

message: Hello fellow Wikipedians,
I have just modified 3 external links on Pharmacokinetics. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
*Added  tag to http://www.revistanefrologia.com/mostrarfile.asp?ID=1566
*Added archive https://web.archive.org/web/20150407143248/http://www.mango-solutions.com/wp/products-services/products/rapidnca/ to http://www.mango-solutions.com/wp/products-services/products/rapidnca/
*Added archive https://web.archive.org/web/20080530085228/http://www.simulations-plus.com/Products.aspx?grpID=3&cID=16&pID=11 to http://www.simulations-plus.com/Products.aspx?grpID=3&cID=16&pID=11
*Added archive https://web.archive.org/web/20110201042414/http://www.pharsight.com/products/prod_phoenix_nlme_home.php to http://www.pharsight.com/products/prod_phoenix_nlme_home.php
When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.
Cheers.—InternetArchiveBot (Report bug) 09:05, 21 September 2017 (UTC)
thread_title:  External links modified 

message: At  there is a need for a section under "Pharmacokinetic data" pertaining to the following: 
* Antibiotic resistance
* Medication Tolerance
If anyone is interested in this topic, please aid in the development of its proper titles, details (for all drugs), most importantly, the drug statistics on the population involving their likelihood for a human body to not respond to it. Hopefully, we can approximate dose quantities that lead to these issues in the long term. Twillisjr (talk) 21:27, 4 September 2018 (UTC)
thread_title:  Template:Infobox_drug