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Topics covered include: absorption (passive diffusion, facilitated diffusion, active transport, endocytosis), distribution (volume), metabolism (phase I, phase II), elimination (zero, first-order kinetics), steady state, cytochrome P450 (inducers, inhibitors)
Amazing video. Very informative. I was wondering if you could make a video with a stepwise tutorial of the phase 1 and phase 2 mechanisms of elimination. My professor’s explanation is a little wonky. Thanks 👍🏻👍🏻👍🏻👍🏻👍🏻
why my nursing school taught me:
zero order drug half life = Initial Conc./2K
First order drug half life= 0.693/K
that means zero order drug elimination depends on the dose
while first order drug is constantly eliminating
This is opposite to yours! WHY?!!! I am so confused.
Anas Yousif Pharmacogenetics is the effects of the genetic factors on the reaction of the drug, Pharmacokinetics is what the Body does to the drug (ADME or LADME) and Pharmacodynamics is what the drug does to the body.
Just wondering how does our body follows mathematics (in reference to first and zero order kinetics)? I mean fixed fraction or fixed amount getting eliminated over a (fixed?) Period of time is something so not random as i first expected...
Grabbing these concepts first yourself and then finding a way to explain in tutorial form to us must be so time consuming and hard work by you. Very impressive!
(How do one present the topics in as much innovative way as you do?)
Think about it like this, you have two workers, one of them can remove 5 cups per minute so no matter how many cups you stack in front of him, the maximum cleared amount in a minute (or whatever unit of time you choose) is 5 cups. The fraction changes because its dependent on the denominator (how many cups are left). 5 cups out of 100 gives you a 5% clearance, while 5 cups out of 5 gives you 100% clearance. The longer the 5 cups per minute is allowed to work without adding new cups, the "more he cleans fractionally" but its always the same number of cups.
On the other hand, your second table has a machine that can only remove exactly 1/4 of the total amount of cups per minute (or unit time). Now we can see that instead of changing the number of cups by a static amount (5 cups) we are changing it based on how many cups are left! As a result, starting with 100 cups, removing a quarter puts us at 75 cups, but the next time the machine removes a quarter its going to drop the 75 by another 1/4! It doesnt care how many cups it removed, only how many are left.
hope this cleared it up
I guess, it's because usually in zero-order kinetics, the drug saturates all your enzymatic systems for excretion/biotransformation, etc... so the rate of elimination is not dependent on the drug concentration and it's fixed over time, so graphically it's a straight descending line.
On the other hand, in first-order kinetics your systems are not saturated and the rate of their reactions is dependent on concentration (see Michaelis-Menten equation).
+an33za It's not really that your body follows mathematics, we come up with mathematical laws to predict and understand the body. In first order kinetics, the more of the drug you have, the more receptors work to degrade it, and usually that fixed percentage of the drug cleared reflects how quickly the receptors can degrade the drug. In zero order kinetics, the receptors have become saturated, so they're doing the maximum amount of work they can do. That means, if you take more drug, you don't have more receptors to breakdown the extra amount of drug, the receptors are already breaking down the maximum amount of drug per unit time, so it's going to be a set amount of drug. These are properties of how the body interacts with the drug, and scientists have observed this and graphed it in order to try to get a better understanding of it. I hope that clarifies a bit
+an33za keep in mind that this is not an exact science. however mathematical models can provide useful insight into pharmacokinetic behavior of a drug despite their much simplified depiction of human physiology. good question
Drawings so amazing making these concepts a lot of fun to remember, and accent is cool n distinctive too with much command over the subject :)
(Btw just curious to know which tablet or software u use for these videos)
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