THANK YOU SO MUCH! I watched several videos and read from different sources, but couldn't understand. Your video made EVERYTHING clear. I really appreciates it *smashes the subscribe button*
Oh gosh!! Doc u nailed it!!! After long time.. For first time it made sense!! And I got the concepts clear.... Thank u for sharing this knowledge with us!! It means a lotttttt.... Thank u tonsss... 🙏🙏thanks a lot Great presentation and I'm totally into this playlist all this day👌👌
I'm very sorry sir, but i have another question. If a drug has high protein binding. Does this not mean it will bind to proteins and less number of it will actually be free, so theoretically and in terms of calculation, the plasma conc. should be low, and the Vd will be high. (Although it means sense that vd should be low since it never distributed).
Areo Saffarzadeh great video sir. The only video that made me understand volume of distribution. But i have a question, how can the plasma concentration be assumed to be the same as target tissue concentration. I mean, isn't a low plasma conc. actually means a large volume of distribution, and so more target tissue conc.???? My question is, how are they (plasma conc. and target tissue conc.) proportional if plasma conc. is inversely related to vd and vd actually determines tissue concentration? Another thing that i can't understand is that isn't the main method of drug transport in body passive diffusion, so shouldn't there be an equilibrium between plasma conc. and target tissue concentration. Please forgive these inconveniences of mine, i know my two questions contradict each other, but i really can't understand. Hope you help me, i know you posted this video 7 years ago, but let me just hope for a reply, and i appreciate your efforst so much
@Areo Saffarzadeh I'm very sorry sir, but i have another question. If a drug has high protein binding. Does this not mean it will bind to proteins and less number of it will actually be free, so theoretically and in terms of calculation, the plasma conc. should be low, and the Vd will be high. (Although it means sense that vd should be low since it never distributed).
Great explanation and you made it look so simple. Also, In problem 2 shouldn't the volume of distribution be 200mg? since only 25% of the drug is available after the first pass metabolism?
Hi doctor Areo Saffarzadeh, I really highly appreciate all of your efforts in this and other videos. I’m wondering about the last question which is asking about the plasma drug conc. overtime while there is no elimination, is the drug gonna be in a high conc. in the plasma, because there is no elimination ? or it should be low because of the extravascular conc. is high?
Areo Saffarzadeh great video sir. The only video that made me understand volume of distribution. But i have a question, how can the plasma concentration be assumed to be the same as target tissue concentration. I mean, isn't a low plasma conc. actually means a large volume of distribution, and so more target tissue conc.???? My question is, how are they (plasma conc. and target tissue conc.) proportional if plasma conc. is inversely related to vd and vd actually determines tissue concentration? Another thing that i can't understand is that isn't the main method of drug transport in body passive diffusion, so shouldn't there be an equilibrium between plasma conc. and target tissue concentration. I know the two questions are contradicting each other, but can anyone help. In desperate need of answer
Hi Areo, Very useful lecture! Would it be worthwhile noting the provided Vd for drugs are based on a 70kg male, and hence the dosage would also vary with patient weight? (and less so with gender and age). T
Hello professor As you said in the last question that new equation about dose and bioavailability And that exactly match with loading dose equation!! So would like to say that we have to remember only loading dose equation Thank you!!
Areo, what program do u use to make these videos. i also teach pharm so i was curious to learn some of your experiences with prerecordings. i use doceri. what abt u?
If you say Vd= amount of drug absorbed into the body/plasma drug conc, What is the difference between the value of the amount of drug absorbed if it is p.o form vs the [plasma]? wouldn't it be the same value? Earlier in the video you say Vd=dose/[plasma] but the dose (mass) would not be the same as the absorbed mass? I'm just really confused.. Does Vd equation use the' dose (mass admin)/ [plasma] or 'amount drug absorbed/plasma' Thanks for the videos though! they are amazing!
Question for you Areo. I understand the concept of APPARENT Vd b/c of low plasma concentrations of a drug. But how do we know that a drug that has a low plasma drug concentration is b/c of a HIGH Vd? What if the plasma concentration is just low because of metabolism & elimination? Thanks for helping to clarify this question. GREAT VIDEOS BTW, I USE THEM FOR MY NURSE ANESTHESIA CLASSES AND TEHY HELP SO MUCH!!!!!!!!!
I think it's because he is using the IV route as an example, hence the first pass elimination is not taken into account because we assume that all of the drugs are absorbed directly into the systemic circulation. If you want to consider the metabolism and elimination factor, you have to include bioavailability in the equation, like in the second example he did.. I'm not sure if it's correct though..
Hi Joe, To go into further detail there is a few Vd that you can talk about, Vd initial- i.e. prior to metabolism and redistribution into other compartments. This underestimates the Vd as there is still most of the drug in the bloodstream (i.e. blood samples taken at 1-3 min). Vd steady state relates to once the equilibrium with the major tissues is reached- this is the one most commonly used, this is samples taken at around 5-10 minutes (depending on the speed at which the drug redistributes out of the blood). The final Vd is the Vd elimination phase, which is once ALL the tissue compartments have reached equilibrium and the drug is only leaving the body by metabolism/excretion (and coming back into the blood from the tissues once the blood concentration is lower!). This greatly overestimates the Vd as the plasma concentration will be very low (and there will have been some metabolism and excretion in the time taken to reach this point). Keeping in mind, these Vd are referring to a 70kg fit and healthy male- to be able to apply them to another person they must first be divided by 70, then multiplied by the patients weight- other age / pathological features must be factored in such as: low plasma albumin in age and starvation, high body fat percentage in obesity, body water composition changes (decreasing TBW with age and dehydration), pregnancy and water/fat content changes.
The amount of drug absorbed in to the body is same as that of plasma drug concentration, then how can we define Vd as the amount of drug absorbed/plasma drug concentration... plz explain
just one correcction. IV drug administration is not a kind of absorbtion because it bypasses the absortion barriers and first pass metabolism. So fastest absorptive rate is in inhalation not IV. You have to differantiate the absorbtion rate and bioavailibility. yes bioav of iv drugs are 100% but not absorbtion rate because they are not absorbed. Just a minor thing but sometimes important to understand. thanks for tutorial
anyone know what would happen if you had to calculate Vd of oral medication - would you have to calculate the amount absorbed or use the dose given if this is what you are given. Bit confused cos altho he says use mass absorbed according to the calculations the actual dose given is what the concentration is
Well, no because the plasma concentration of that drug will be low since it will go to its site of action and therefore have a low plasma concentration... This means the Vd will be High since it has low affinity. But, if a drug has high affinity to plasma proteins, they are "trapped" in the plasma hence, their Vd will be low due to high concentrations of plasma. I.e. They are not distributed well through the body.
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10 years later, your set of tutorials on PK remains the best. The simplicity with which you teach is brilliant
Thank you for focusing less on memorizing new equations and instead focusing on the concept where they come from. Love your approach.
This is the best explanation that I have seen, on RUclips, about the volume of distribution. Thank you for taking the time to make these videos!
I lived before youtube. My life would have certainly turned out differently if I had such a wonderful resource like this back then. Thank you!!
Absolutely fantastic overview of the volume of distribution! Thank you so much!
you are actually the best. The way you do mini tests throughout the lectures really helps too. thank you.
I can't thank you enough ! I finally got a grasp of the whole thing
After all these years of vague knowledge about Vd, This video explains everything so clear. You're so amazing! Thank you Professor.
So helpful! I've been confused by this all semester long; you are clearing my questions up with a short
Concise and effective lectures! Thank you for making these vids; they're amazing
Now I can define it conceptually.Now I am very happy.Spent 2 hours on that.
THANK YOU SO MUCH! I watched several videos and read from different sources, but couldn't understand. Your video made EVERYTHING clear. I really appreciates it *smashes the subscribe button*
I did mass in case of bioavailability with the help of analysis it's because of you.Thank you sir great jot
I am so happy that I could find this. I cant believe it that i can understand
Here 8 years later and still helpful!
Thank you so much
Oh gosh!! Doc u nailed it!!! After long time.. For first time it made sense!! And I got the concepts clear.... Thank u for sharing this knowledge with us!! It means a lotttttt....
Thank u tonsss... 🙏🙏thanks a lot
Great presentation and I'm totally into this playlist all this day👌👌
Thank you for making this video, doing my Emergency medicine primaries at the moment and I have found this invaluable.
Much Better than my pharmacy professor
I really appreciate it
Thank You for this, seriously. I finally understood this concept!
This was very helpful. This concept was introduced last semester, but I always felt I had a very poor grasp on it until now.
Great video, for the drug sequestered in the the fat and muscle are they active?
Best explanation👏🏾
dude.. u just saved me!!! awesomeee!!!!!!!
I'm very sorry sir, but i have another question. If a drug has high protein binding. Does this not mean it will bind to proteins and less number of it will actually be free, so theoretically and in terms of calculation, the plasma conc. should be low, and the Vd will be high. (Although it means sense that vd should be low since it never distributed).
Your videos are very useful and they are very precise.plzzz post more videos in pharmacology.thank you very much...
Thank you professor! You're really a lifesaver.
good catch, thanks!
Areo Saffarzadeh great video sir. The only video that made me understand volume of distribution. But i have a question, how can the plasma concentration be assumed to be the same as target tissue concentration. I mean, isn't a low plasma conc. actually means a large volume of distribution, and so more target tissue conc.????
My question is, how are they (plasma conc. and target tissue conc.) proportional if plasma conc. is inversely related to vd and vd actually determines tissue concentration?
Another thing that i can't understand is that isn't the main method of drug transport in body passive diffusion, so shouldn't there be an equilibrium between plasma conc. and target tissue concentration.
Please forgive these inconveniences of mine, i know my two questions contradict each other, but i really can't understand. Hope you help me, i know you posted this video 7 years ago, but let me just hope for a reply, and i appreciate your efforst so much
@Areo Saffarzadeh I'm very sorry sir, but i have another question. If a drug has high protein binding. Does this not mean it will bind to proteins and less number of it will actually be free, so theoretically and in terms of calculation, the plasma conc. should be low, and the Vd will be high. (Although it means sense that vd should be low since it never distributed).
By the end od 2020, my Allah bless u ❤️
Many thanks
Great video!
great video, i just missed this point: does increased capillary permeability lead to a high or low Vd and why?
Very cool video - thank you!
God bless you for such a nice teaching
Could you please provide videos of lecturer series 14 and 15
Literally.. Thank you so damn much.. For making me understand this.... ❤️ ❤️
really thank you so much Dr. Saffarzadeh your truly amazing 👍👍👍
REALLY HELPFUL VIDEOS.THANK YOU VERY MUCH SIR.
Excellent video series thank you sir
At time 10:32
It's fifteen thousand litres
Or One hundred and fifty hundred litres
Not one hundred and fifty thousand litres
Just a correction ;)
+Joseph Butawo
Or one hundred and fifty thousand liters ***
@@ameersaied894 doesn't matter how you spell litres/liters, same as aluminum/aluminium
Thank you so much,😍😍😍😍😍💙💙💙💙💙💙💙
Fantastic lecture. Thank you very much.
Thank you so much. Brilliant.
really thanks too much Dr for explaintion .. doctor can u explan the factors that increase and decrease vd .. and the reson for this factor in detail?
10:31, I'm pretty sure that's 15,000, and not 150,000... No big deal! Excellent video!
15000 it is
thank you so much it was super helpful ^-^
Great tutorial. Most abundant protein in the body-- COLLAGEN. :)
Clear explanation!!!
these are amazing, thank you!
Thank you so much...! It really helped out.
What books do you recommend? I'm now studying Basic and Clinical Pharmacology, B. G. Katzung
You saved my life !
Also, please make a video on how and when to apply the logarithmic trapezoidal method to calculate AUC.
Thank you, wonderful video
Thank you very much for explaining such difficult objective🥰
Please make a video on how to calculate patient specific Vd and AUC--perhaps addressed by the Sawchuk-Zaske method?
Good work .Thanks a lot 👍
you are wonderful!!!
Thanks for the great videos
Great explanation and you made it look so simple. Also, In problem 2 shouldn't the volume of distribution be 200mg? since only 25% of the drug is available after the first pass metabolism?
Thank you so much sir.
Stick with what you got its a good book
please can you continue explaining pharmacology
The best
Very helpful !
Thank you so much for the explanation.
Thank you alot
Thank you sir
Thank you
Brilliant..
Hi doctor Areo Saffarzadeh, I really highly appreciate all of your efforts in this and other videos. I’m wondering about the last question which is asking about the plasma drug conc. overtime while there is no elimination, is the drug gonna be in a high conc. in the plasma, because there is no elimination ? or it should be low because of the extravascular conc. is high?
Thanks a lot sir!
Areo Saffarzadeh great video sir. The only video that made me understand volume of distribution. But i have a question, how can the plasma concentration be assumed to be the same as target tissue concentration. I mean, isn't a low plasma conc. actually means a large volume of distribution, and so more target tissue conc.????
My question is, how are they (plasma conc. and target tissue conc.) proportional if plasma conc. is inversely related to vd and vd actually determines tissue concentration?
Another thing that i can't understand is that isn't the main method of drug transport in body passive diffusion, so shouldn't there be an equilibrium between plasma conc. and target tissue concentration.
I know the two questions are contradicting each other, but can anyone help. In desperate need of answer
You are good man! Can you help me with how to make a simple video like this?
Hi Areo,
Very useful lecture!
Would it be worthwhile noting the provided Vd for drugs are based on a 70kg male, and hence the dosage would also vary with patient weight? (and less so with gender and age).
T
superb
thank you so so much.
i love you. in every way.
Hello professor
As you said in the last question that new equation about dose and bioavailability
And that exactly match with loading dose equation!!
So would like to say that we have to remember only loading dose equation
Thank you!!
Areo, what program do u use to make these videos. i also teach pharm so i was curious to learn some of your experiences with prerecordings. i use doceri. what abt u?
I was wondering the same thing!
Thanks!!
FREAKIN LOVE YOU
very useful
If you say Vd= amount of drug absorbed into the body/plasma drug conc, What is the difference between the value of the amount of drug absorbed if it is p.o form vs the [plasma]? wouldn't it be the same value? Earlier in the video you say Vd=dose/[plasma] but the dose (mass) would not be the same as the absorbed mass? I'm just really confused.. Does Vd equation use the' dose (mass admin)/ [plasma] or 'amount drug absorbed/plasma' Thanks for the videos though! they are amazing!
Some books quote VOD in L per kg, can you please explain why?
Good one sir..helped me a lot :-) Just one doubt how low molecular weight drug has high Vd?
+Shallu Khatri low molecular weight means the molecule will be relatively small, this increases its diffusion rate which would explain its high Vd. :)
George Burchell ohkay..got it now .. :-) Thanks :-)
Sir make videos on pharmacodynamics 😌
Question for you Areo. I understand the concept of APPARENT Vd b/c of low plasma concentrations of a drug. But how do we know that a drug that has a low plasma drug concentration is b/c of a HIGH Vd? What if the plasma concentration is just low because of metabolism & elimination? Thanks for helping to clarify this question. GREAT VIDEOS BTW, I USE THEM FOR MY NURSE ANESTHESIA CLASSES AND TEHY HELP SO MUCH!!!!!!!!!
Very good question raised also by others - I would like to know also.
I think it's because he is using the IV route as an example, hence the first pass elimination is not taken into account because we assume that all of the drugs are absorbed directly into the systemic circulation. If you want to consider the metabolism and elimination factor, you have to include bioavailability in the equation, like in the second example he did.. I'm not sure if it's correct though..
Hi Joe,
To go into further detail there is a few Vd that you can talk about,
Vd initial- i.e. prior to metabolism and redistribution into other compartments. This underestimates the Vd as there is still most of the drug in the bloodstream (i.e. blood samples taken at 1-3 min).
Vd steady state relates to once the equilibrium with the major tissues is reached- this is the one most commonly used, this is samples taken at around 5-10 minutes (depending on the speed at which the drug redistributes out of the blood).
The final Vd is the Vd elimination phase, which is once ALL the tissue compartments have reached equilibrium and the drug is only leaving the body by metabolism/excretion (and coming back into the blood from the tissues once the blood concentration is lower!). This greatly overestimates the Vd as the plasma concentration will be very low (and there will have been some metabolism and excretion in the time taken to reach this point).
Keeping in mind, these Vd are referring to a 70kg fit and healthy male- to be able to apply them to another person they must first be divided by 70, then multiplied by the patients weight- other age / pathological features must be factored in such as: low plasma albumin in age and starvation, high body fat percentage in obesity, body water composition changes (decreasing TBW with age and dehydration), pregnancy and water/fat content changes.
thanks
The amount of drug absorbed in to the body is same as that of plasma drug concentration, then how can we define Vd as the amount of drug absorbed/plasma drug concentration... plz explain
just one correcction. IV drug administration is not a kind of absorbtion because it bypasses the absortion barriers and first pass metabolism. So fastest absorptive rate is in inhalation not IV. You have to differantiate the absorbtion rate and bioavailibility. yes bioav of iv drugs are 100% but not absorbtion rate because they are not absorbed. Just a minor thing but sometimes important to understand. thanks for tutorial
Highest absorption rate should be sublingual route
Right?!
@@themasry5022 all parenteral bypass metabolism that doesn't mean they are fastest
IV or Inhalations are much faster
From Al-quds university? Thumb up
thanks :)
What is the meaning of drug plasma concentration?
Free or albumin bound drug
Or the total drug concentration in plasma
+The Masry It means the total drug concentration in plasma (free drug in plasma and drug bound to plasma proteins)
kimphat18 ok thanks alot
So you take the bound fraction in consideration while measuring the drug concentration, even though the bound part won't have any effect?
anyone know what would happen if you had to calculate Vd of oral medication - would you have to calculate the amount absorbed or use the dose given if this is what you are given. Bit confused cos altho he says use mass absorbed according to the calculations the actual dose given is what the concentration is
Thanks !XD
Well, no because the plasma concentration of that drug will be low since it will go to its site of action and therefore have a low plasma concentration... This means the Vd will be High since it has low affinity. But, if a drug has high affinity to plasma proteins, they are "trapped" in the plasma hence, their Vd will be low due to high concentrations of plasma. I.e. They are not distributed well through the body.
Btw, @10:28, it's 15,000L not 150,000L
stay in plasma some book said it 5L is enough
attribute = ˈatrɪbjuːt/
8 ads ffs wtf
helpless