Pharmacokinetics 2 - Absorption

[@collinsokafor8692]

Why did you stop making videos dude 😭. This is amazing

[@harpinmartin]

Hi, Thanks for the feedback, however in this video I have explained that we are measuring the drug concentration in the arterial system. So although you are correct in saying that the maximum bodily concentration is at time=0, the maximum bioavailable drug concentration occurs after distribution through the whole vascular compartment. A good example of this is multi-phase CT scanning, where you can see the IV contrast moving into different compartments.

[@ishadeshwal5984]

I have a question that if we adminster a drug through intraarterial so. What's happen???

[@himohamza7097]

I have a small note .. using IV administration the C(max) is reached at time ZERO so there is no upraising in the concentration and then falling down . It starts from the top of the graf at a concentration equal to the dose given and then drops gradually

[@tamakimasumoto7340]

but distribution is not instantaneous? its rapid but not instant

[@yousfmostfa]

Minute 4:42. The area under the curve AUC is not the same in all routes it’s different, It’s higher in IV administration and smaller in Oral administration even though it’s the same dose.

[@niraxlevi9930]

Exactly he makes many mistakes

[@niraxlevi9930]

It's also obvious since a part of the drug is lost when administrated orally

[@sofiaahmed6415]

Every time I watch your video I always regret that such a great knowledge is stopped from not uploading again.

[@getinspired3499]

One of the best explained videos in KZbin. Thank you

[@raghad64]

I’m a 5th stage pharmacy student and I’m attending this cuz I have final online exam of Therapeutic Drug Monitoring during quarantine... wish me luck 🙌🏻🎓

[@j0562]

Raghad I know you probably finished it, but good luck.

[@islevenc]

how did you get on, pls share

[@dennisneezy7311]

Utapita..

[@buqbooQ]

@@islevenc did you pass?

[@amandeol5711]

Ur lectures are way toooo good. Thank you so much for helping.

[@sarahgom9710]

This is the video I was looking for thank you! I've been trying to find a video on youtube for hours!

[@ritaborges5348]

The IV curve is wrong, it should start with maximum blood concentration at T0. There are four main components of pharmacokinetics: liberation, absorption, distribution, metabolism and excretion (LADME). To inject a substance via IV that substance must have some degree of solubility , so you skip the first step : liberation, since you put the drug directly into the blood stream, there is no need for absorption. The IV drug will be ready for distribution from the start.

[@MsRuru1]

I agree

[@Tish418]

I was wondering about this. Also is the AUC really the same for each form of administration like he said? Wouldn't that mean the bioavailability for each is the same, which I don't think is true. I'm pretty new to all of this though.

[@CharlieNash1]

actually you are only correct if we assume immediate distribution across all of the blood plasma (i.e. one compartment model) but in reality, it wont be max at time 0, because distribution is not immediate. You can estimate theoretically what cmax would be by extrapolating the log concentration graph backwards then calculate your Vmax

[@physicianassistant1014]

This is amazing. Thank you. Summarized a 3 hour lecture.

[@keepnitsharp]

You are a Godsend I wish I would have found your channel a long time ago.

[@ubbinkadrienne]

Thank you. As V.K. mention, with IV all of the drug is available in the blood at once, but still have to take one or two minutes to reach the entire system.

[@farhanabrishty3667]

Such a great way to clear concept. Thank you so much Sir for helping us understanding the process.

[@juwitajunit4250]

These are fantastic, thank you so much for the visualization. Really appreciate your work!

[@armennazarian1976]

The terminal half-life (t1/2) of a compound following i.v. administration is determined by its distribution and elimination. Generally, since distribution is much faster than elimination, the terminal half-life is governed by its elimination. As a result, t1/2 values may differ significantly between species, with smaller species, e.g., mice, which generally have a higher metabolic rate, exhibiting shorter t1/ 2 values for compounds than larger species (such as human). In contrast, the terminal half-life determined following other routes of administration may be governed by the absorption of the compound from the site of administration, in addition to its elimination and distribution. The latter occurs if the absorption process is rate-limiting, and to determine whether this is the case, the t 1/2 value estimated from i.v. administration is compared to that following the non-parenteral route of administration (e.g., p.o.). Equal values for t1/2 would suggest that absorption is not rate-limiting. And lastly, total body exposure to the compound, as determined by the area under the blood/plasma concentration versus time curve (AUC) from time zero extrapolated to time infinity (AUC0-inf), following i.v. dosing is used as the reference (100% is available) for estimating the bioavailability (%F) of a compound following non-parenteral routes of administration.

[@nathalie1960]

So basically, for all those statements he says at the end of the video he is asuming: F=1, and the individual is the same, right? I was very confused when he said all the AUCs where the same (knowing F=AUC(extravascular administration)/AUC (oral administration)) it did not make much sense to me. But asuming those things what he said might be correct?

[@shaemez]

half-life is the same. If you have a higher concentration, removing half of that higher concentration requires you to remove MORE of the drug, hence explaining why the half-life stays constant. sorry if it makes no sense

[@OmarAli-py3pq]

Incredibly useful; thanks from IRAQ🇮🇶🤩

[@CbarMiiXaaS]

Surely if you inject IV you begin at 100% blood conc?

[@CharlieNash1]

thats if you assume immediate distribution of the drug into the one compartment model, but it has to be cycled through the lungs and heart first before distribution across all the plasma. Often to simplify we assume that distribution in the blood is always equal and immediate but that is not always the case. We can only estimate the concentration of the drug at immediate administration (assuming one compartment model) by use of extrapolating the log graph of concentration back to time 0.

[@marcobiondi7574]

From the time of injection to the actual drug distribution there is a non steady state which is not taken into account when drawing the bioavailability curve, as Charlie explained.

[@kyleb4779]

He is looking at arterial concentration, not venous.

[@ezhumalaig3498]

Excellent. very clear and easily understandable for me (Statistician)

[@rashid8331]

Last video on this channel was posted about 6 years ago.. I am worried 😯 about this guy. what happened to him?? Anybody knows the reason?

[@Okaythankyoubye]

4:40 How is the AUC the same for all where as the IV and Inhalation do not go through the first pass effect?

[@BaffledBrain987]

Love your tutorials... too good plz keep up... looking forward for more videos

[@karenchan8713]

Hi! These videos and the infographics are awesome. I'm an RN who is tutoring now and I wish I had these in school. I'm also an artist and wondering if this is hand-drawn or done w/ the aid of a computer program such as Ilustrator / or a tablet? Thanks!

[@danacarver8197]

Oh, and I love your tutorials. Very clear and concise.

[@carolodonnell4777]

As several of the comments state, the profile for IV absorption of drug is not usually represented as you have shown and I think you are confusing people. IV absorption is considered the fastest way to get drug into the vascular system.

[@lina94dhyaa23]

الف رحمة ع روح اهلك ع هل الشرح .... منتاز

[@17ReeM17]

u should be my doctor T_T thanks for these awesome videos! greetings from Saudi Arabia ♥

[@arshadansari6940]

concentration of drug from iv route should be max. I think..

[@Baharaakbari]

that was quite amazing but what about IM ???

[@Porsh27]

Enteral: Oral and Rectal Parenteral: IM, IV, SQ, Inhaled, topical, transdermal.

[@soccerskillz95]

Cuz wouldn' t the IV conc start from the top of the y axis

[@AlwaysSummer22]

My understanding is that the medication is inserted into a vein not an artery. I think this percentage pertains to the specific arterial concentration, not venous.

[@Soloboy1122]

I still didn't understand why inhalation has less lag phase as compared to iv. I mean iv has 100% absorption where inhalation has to cross a membrane

[@jaredwilsey4497]

Enrique Iglesias Inhalation bypasses veins and right side of heart, so what is absorbed is almost immediately available for systemic distribution. Bioavailability for I.v. is higher, 100% by definition, but must make it to left heart before it can be distributed

[@Mrjmaxted0291]

Thank you for this. Brilliant input.

[@VibeWithVida]

Exactly what I was looking for. Thank you.

[@dariocosemans9151]

The AUC can't be the same if you give the same dose with different administration ways, right?. The AUC is the the total exposure of that drug to the body. And this exposure differs between administration ways. My question is: When the absorption happens nearby the enterocytes. Does all of the drug get absorpted by the enterocytes (and than a fraction gets metabolised) or does a fraction just go with the flow to the exit?

[@maya3187]

First off I would like to tell you that your tutorials are awesome and are helping me TONS! Second, I don't understand how the half life would be equal in all three routes. If a higher concentration is excreted at a higher rate, then the half life would be smaller...right? So the half life of an IV drug would be shorter than that of an oral drug...please correct me because I just dont get it :(

[@pranavsairaman8949]

Same doubt!

[@FolkenSRK]

But you give the same drug less in IV form than oral, no? I don't really understand how they could have the same half-life.

[@mahmoudnassar3135]

Same here ... Could u plz explain this point more ??

[@ToniVaughan]

The half life of a given drug is always the same, it has nothing to do with the route of administration. Also, as for the faster drop in concentration, he mentioned in the video that in this example the drug follows 1st order kinetics which means the rate of elimination is proportional to the concentration the drug.... higher concentration = faster elimination

[@zainanwar9281]

this is my understanding.... yes the higher the concentration the faster it excretes it but higher concentration also means theres more of the drug present so the body also has to work longer and harder to excrete it. generally it ends up taking the same amount of of time for different concentrations because your body takes a certain amount to expel half the drug no matter the concentration...... I repeat this is just my understanding right now based on my limited knowledge so i might be completely wrong

[@anasan9377]

Rectal drug administration (kids) is there First pass effect or NOT? Thanks!

[@AMJ.JAGUAR]

I've seen another video mentioning that the drug will be subjected to first pass effect as it passes through the portal vein to the liver. But rectal plexus, consisting of the 3 veins ( superior, middle, inferior ), drains into inferior vena cava as well. I don't know at which level the suppository or the injection will be, but the higher it gets the more the likelihood of getting into the portal system through the superior rectal vein !!

[@xDomglmao]

We learned in med school: partial first-pass.

[@vkmourya]

The plasma profile after intravenous administration is not one, which is shown in tutorial, please correct it. It doesnot have Cmax and tmax because whole drug is available to blood pool at the beginning itself.

[@ciroesposito5395]

What are plasma concentration fluctuations?

[@elvinluccon3394]

What if you give the drug through an artery would it be the same as the venous one? Or arterial would be faster?

[@angellibra3432]

Plz keep working on pharma I really need your help.... God bless you may you succeed Amen 💕

[@someonethinker9057]

AUC (area under the curve) is the biodisponibility ???right ... I am not sure about the eng term but in French we say "biodisponibilité"

[@samanthapacker18]

You explained this so well!!! Thank you!!

[@sloane290]

This stuff is gold.

[@atulkamble125]

Your lecture are always good to watch #pacepharma

[@itsshimaa1467]

How the area under the curve is the same in three routes?

[@BuildItfromNirvana]

It can't be! because oral administration there IS a % of elimination of the drug through the first pass effect

[@mariamhijazi4128]

So for the IV compared to oral, shouldnt the graph shift to the left since the variable here is the time and Iv takes less time , so why it is also shifting upward ? This is the only part i dont inderstand. Thank u

[@emmaswan7453]

Mariam Hijazi as far as I understand: IV application is faster (curve is more straight), the whole dose of a drug comes faster in arterial system and reach higher concentration (shifting upward).

[@amit8299]

After the drug are absorption pass in to blood than what is the work of antibiotics and antigen on that time

[@Moss9100]

Hi sir. Im quite unclear on the area under the curve part. You said the area under the curve is the same for all the route of administrations, when the dose is the same? If someone gives the drug orally, will the same dose reach the blood circulation system as i.v? Will the bioavalability be the same? Please im confused help me here

[@mahmoudnassar3135]

DZO Hams yes they are the same but if u deal with the whole body as one compartment ... The same dose orally enters the body equals that for the one administered by iv route but takes much more time ... Mathematically if u calculate the area under the curve using integration u will get the same result

[@brasilsoccer0]

How is the cMax the same for oral vs IV Med??!!

[@Dr.light2.0]

Madagascar Sapphire no it's not...oral cMax is lesser comparatively than iv cMax ...as shown in the video

[@strickdan44]

I presume the curves are not true scale? If it is to scale, then the T1/2 for the various routes is not the same. I printed it and measured.

[@psp4191]

Excellent effort

[@hbvaidya]

why drug going to liver direct after absorption??? is it first pass metabolism?

[@maryleban7973]

First pass metabolism is effect of passing through the liver on the medication

[@Vunami]

What about for patches?

[@siwardhawadi9561]

I like your tutorials ❤

[@doctorbase2364]

Sorry but i couldn't understand why T1/2 is the same regardless the route of administration , can somebody help me ?

[@sexymeowz]

Hi..........your explanation is really good.....but i would like to correct one point that is AREA UNDER CURVE IS DIFFERENT FOR DIFFERENT ROUTES OF ADMINISTERATION ......BCZ WHILE CALCULATING BIOAVAILABILITY WE TAKE AUC OF ROUTE UPON AUC OF INTRA VENOUS ROUTE AND MULTIPLY BY 100!!! SO HOW CAN AREA UNDER CURVE BE SAME? thankyou

[@SuperMacGeek]

Sorry I don't quite understand you're argument for the Area Under the Curve? Could you please explain? The only reason I can imagine the area would be different is for the case when oral drugs in particular which pass through the 1st Pass Metabolism, whilst the other drugs go systemically first.

[@bahramebrahimi6075]

Great , thank you very much. Pretty good and useful

[@19sandhyagawali]

This is the best video🙂

[@riddhigangoli3950]

These videos are really helpful! TYSM

[@yashikadalora5294]

Really helpful .... pls make more videos

[@kaizendiva2939]

thank youuu ao much that was so much helpful

[@harpinmartin]

This is correct.

[@lfcrags9715]

Will this help if I wanna become a doctor

[@latifahll7074]

who knews

[@romeoreaso]

Drug have higher concentration in blood in IV route so graph will not start from zero

[@marcobiondi7574]

Very well organized tutorial, but the IV curve must be corrected as its trend is simply wrong.

[@Kencan254]

Now that you want to fake so knowledgeable, why don't post your own series of video, pretender. Fuck off.

[@dirghammaniar]

What about intramuscular

[@DollyDomDom]

I wish you did IM route!

[@sanampudichandikareddy5265]

It meant that which one has high bioavailability

[@roseforman9911]

Another great video

[@romeoreaso]

I think you may wrong in way of drug through IV routr

[@bookworm6920]

Amazing 👏🏻👏🏻👏🏻👏🏻

[@mirhanaheed732]

Intramuscular?

[@desyibelewbayilie5501]

well lecture. thanks to all

[@TheSweetasheaven]

yes you are. Keep it going! I love it.

[@zainabidrees7898]

Really helpful

[@colindesj10]

Is this for illegal drug use too?

[@sanjeewaanilkumaralokuhett200]

very useful, thanks

[@hllxyd6653]

ty helped so much

[@krishanthi_nz5293]

Thank you so much

[@vijayanandveterinarian7616]

If concentratin is high excretion is low only know...so the drug half life also high know...but u told if conc of drug high excretion high..

[@_Favvy___]

Is this Armando?

[@sashahanna3792]

Very Useful!!!

[@sisaygebremedhn3183]

good

[@rahimhaqani5534]

where is the role of kidney

[@Multiplicationchu]

Why the half life is the same?

[@tinafatih5011]

thank you ! /dental student

[@yaroslavyoutization]

nice ones! cheers

[@TosinTime]

AMAZING

[@fatmahani8002]

you are the best! :)

[@sohailmusawar]

Great

[@trinisty]

Make more videos! :D

[@hanalotfi7702]

Best one

[@ghadahsalem9965]

Its too good.

[@abdulmohsinmarghalani4997]

u r a legend

[@afifiadi740]

amazing :)

[@aneethgangwaraneeth1905]

Sir video hindi me please

[@serasamar]

His hands are like my ex ...sad xD

[@charuraya2606]

Great