Bioavailability and First Pass Metabolism

[@Mollythom94]

For anyone struggling with his math... 70% of 300mg is 210mg entering hepatic portal system with the remaining 90mg being excreted through feces 60% of that 210mg entering the liver is deactivated by the liver resulting in 126mg of the drug being inactivated. 210mg - 126mg = 84mg or 28% of initial dose entering systemic circulation with its bioavailability intact. Hope that helps.

[@gelaiiyke8689]

Yes! Thank you so much

[@Letsgetdancing_]

Thanks a lot

[@44-burhanuddin89]

My methodology is also this

[@stranger.97]

Thanks

[@ayisha1943]

Hello! I didn't understand one thing why would we subtract 60% from 100% when 70% drug reaches the portal system and 30% already removed from faeces even before reaching portal??

[@vikas-li3hf]

Sir im vikas kumar from India in Lucknow city You so esaly study i understood little You are teaching good God bless you

[@braid9548]

this is a great video!! you explain First pass so clearly!! Its a shame i can't reference a youtube video for my assignment :(

[@xtinesssss]

Can you explain in your last question how it would be higher? I thought when taken orally it causes a lower effect because not everything is metabolized as opposed to parenteral route where it has a higher effect because it goes straight to circulatory. Can you explain that part?

[@Dr_ahmedfouad]

It would be lower because first pass effect, that’s why the availability of IV is %100. The answer is wrong

[@areejahmed9188]

He is asking about the dose that should be taken orally to give the same effect that IV route give so you need to make the dose higher because of the first pass effect (not asking if the effect would be higher or lower)

[@Dr_ahmedfouad]

@@areejahmed9188 صحيح عاشت ايدج ✅

[@werdsdanoliees7871]

Dosage

[@jameswhitaker4357]

Not a med student but love to do health studying. This explains a lot very effectively. Thank you sir! I’m in the Data Science field so the math was refreshingly simple. It’s more of understanding processes, eh? Orally our drugs will never be 100% bioavailable.

[@physiopathopharmaco4190]

Awesome James - love your curiosity for learning!

[@jameswhitaker4357]

@@physiopathopharmaco4190 it helps a lot, when explaining to my grandmother why she should seek foods that are bioavailable in b12 vs the vitamin form. And the fiber benefit and w/e. My curiosity comes from taking the right amount of vitamins + eating foods with high bioavailability of those vitamins we need. 🙂

[@Bmarker299]

Excellent! Well done. Gifted teacher. Beautiful voice

[@physiopathopharmaco4190]

Wow, thank you!

[@dianawilliams6869]

You should do like a voiceover for a video game (like a walkthrough) unrelated but I think it would work together

[@danielclarke2577]

amazing made a complex subject easier and the 2 questions at the end really helped

[@suryaprasantnaram5141]

Its an awesome explanation through how drug works in the body

[@eubutuoy]

Is there a database that lists chemicals and information about first-pass metabolism?

[@syedaamerahussaini8925]

Thank you sir! It is very helpful! Got the concept really quickly!

[@physiopathopharmaco4190]

That’s great thanks

[@complex5813]

-First pass metabolism is the broken down action of the liver. -Bioavailability is a percentage

[@장보윤-q9v]

Very clear and understandable even for non-english speaker! Thanks!!! :)

[@tiki4045]

Thank you! Awesome breakdown.

[@bitchimee2952]

hey, please why would you subtract 60% from 100 if 30% was already removed through faeces. shouldn't it be 60% subtracted from what got into the liver which is 70% ?

[@physiopathopharmaco4190]

You would multiply 70% by 40% since these were the %s that moved on at the 2 points they could have been taken out.

[@ralphsmith2683]

YOU are CORRECT and HE is NOT

[@otterley_3041]

THANK YOU SO MUCH,. You are a godsend!

[@physiopathopharmaco4190]

That’s very generous, thank you

[@raoarslan3754]

This help me alot and got complete Concept about this But I dont Understand the Last Question only.

[@ayadwidar8824]

It was simple and useful thank you so much ❤

[@clarity8296]

Love the content. What do you use to create your videos?

[@zamanmakan2729]

Thanks a lot! I'm wondering if first pass is part of phase 1 or do first pass and phase 1 happen at the same time for prodrugs? Thanks a lot

[@BaoTran-ls7oy]

Thank you for this video!

[@physiopathopharmaco4190]

You are so welcome!

[@Jiha-ed9lv]

Thank you sooo much. Very helpful!,,

[@physiopathopharmaco4190]

Glad it was helpful!

[@michaelavillanueva203]

Thanks man, helped me understand my lesson

[@shashidutt5012]

You are an excellent teacher!

[@aliayad5967]

Shouldn't the answer be B because of first pass effect ??!

[@physiopathopharmaco4190]

Remember that intravenous bypasses the 1st pass effect, if you are changing to oral, now you have 1st pass effect so to compensate you must increase the dose

[@aliayad5967]

Ohh, i must misunderstood the question thanx for for explaining it's been a great helpful

[@yeshuasage3724]

@@aliayad5967 misunderstanding the question costs many pharma students Its almost an english test as well as a pharma test Always read the q many times over and good luck

[@trickstertrip5962]

Got me too 😅😅😅

[@truebeliever6437]

do IV, intradermal, rectal drugs get metabolized by the liver?

[@physiopathopharmaco4190]

Yes but not on the first pass

[@truebeliever6437]

wow quick reply thanks

[@Prfinity]

Useful concepts

[@seedsofhope8643]

OMG! Thank u so much, such an amazing video :)

[@kabiswaaugustine7264]

The answer is A because first pass effect reduces the bioavailability of the drug thus we need to administer a higher dose to

[@katherinec8396]

This is a awesome explanation!

[@ralphsmith2683]

AN awesome...NOT a awesome

[@idilmohamed_]

This helped a lot! THANK YOU.

[@physiopathopharmaco4190]

Awesome- you’re very welcome 😊

[@CilmiFaafiye]

Idil maxamed adiga ila somali ah ee seetahay wll ? hhhhhh mar arday medicine ah bad tahay wll ?

[@pingmacalos500]

sir thank you very much for this!!!

[@zopilote_4000]

can first pass metabolism vary? like can i take a medication and one time it gets absorbed a lot and then the next not as much? can it vary based on food consumption or other factors? is it different in different people? or is it constant for a drug?

[@dr.sohataher9413]

Ofcourse it vary with food.. See omeprazole and sulfur containing drug..

[@medicalscience1528]

Good Question !

[@tubamalik9232]

good explaining

[@adamstevens5518]

The thing I don't understand is, I see sources that say 50% of stomach contents empty in 2.5 to 3 hours, yet oral drugs can take affect in less than an hour in some cases. If most of the drug doesn't get emptied from the stomach for hours, how does it take affect so fast? It goes directly from the stomach to the bloodstream?

[@stephanieosmond5059]

My understanding would be that because the drug that doesn't get emptied is then going to systemic circulation whereas the drug that has been moved onto to be emptied has one been modified or broken down then does it have to travel through the rest of the GI system?

[@truebeliever6437]

which is better for a patient with cirrhosis to receive? IV Tylenol or IV Fentanyl and IV Hydromorphone?

[@physiopathopharmaco4190]

Hepat Mon. 2014 Oct; 14(10): e23539. Published online 2014 Oct 11. doi: 10.5812/hepatmon.23539 PMCID: PMC4250965 PMID: 25477978. “Because of its proven safety profile (when given in recommended doses) and the lack of sedative effects and absence of nephrotoxicity, acetaminophen is the preferred analgesic in patients with liver disease including cirrhosis. However, because acetaminophen overdose is known as one of the most common cause of liver failure, it is not surprising that the majority of pain practitioners are not willing to prescribe it to patients with any form of liver disease.”

[@rehamgamal3285]

Nicely subscribed.

[@gladysma308]

2:06 Bioavailability

[@dalilaalves3938]

Very well explained! Cheers 😉

[@vikas-li3hf]

Hiii i am vikas from India

[@SanjeevKumar-lt1wc]

Thanks very much

[@bhuvaneshwariravichandran8202]

Please explain that why we should subtract 60% from 100% not from 70% which is the percentage of drug that gets into the liver as the 30% of drug is already being excreted into feces

[@sullypwz7864]

how do drugs flow to hepatic arteries? i thought blood only flow from artery to cappilaries not opposite.

[@xixi2693]

Sir please I have a question When everything exists within nature, whether it is vegetable fruits or allopathic medicine, how the body detects that allopathic medicine is a foreign material ? ? Because allopathic medicine is man made but it from a combination of the matter that exists within the nature so we consider it as natural. Then how the body detects that allopathic is foreign material ?

[@karthiksadanand3350]

Though I'm far from an expert in this field, I assume anything foreign that the body encounters (after being ingested) will be absorbed and then passed through the liver. After all, vegetables and fruits are just made of organic matter that can then be broken down. This will then be absorbed into the bloodstream and can the be passed through the liver (for metabolism). This is an evolutionary mechanism I believe to make sure that the chance of any foreign molecules causing harm to humans is drastically minimised.

[@kasunrodrigo6592]

Very correct as per my understanding. Alcohol is a great example of such a mechanism very interesting to understand if you could dig deeper

[@passntesam3346]

❤❤❤❤

[@aliaelfaham6131]

Thank you very much 🌼

[@dorianken1487]

you're amazing, thank you!

[@medicalscience1528]

So in simple words , we can say that liver eliminate 'extra drugs' and keep only that amount in body which is needed ? Please help clear the concept.

[@zizojaezekeom3565]

No we can't say that because the liver isn't conscious about what it's doing, it doesn't know what's the important amount you need

[@medicalscience1528]

@@zizojaezekeom3565 Ok. Thanks. Then how this mechanism work ? Can u tell if u know

[@ruththompson5280]

Good stuff

[@mycenaeangal9312]

Does this scale linearly with dosage?

[@amawor5404]

thank you god bless u

[@pramudimekala2959]

Thank u so much, that is so helpful😊

[@doctorbase2364]

Super amazing

[@lanyafalah2028]

Thank you so much 🥰

[@Dr.BelloAliyu]

What's the main difference between Bioavailability and Biotransformation because I'm totally confused sir.

[@physiopathopharmaco4190]

Biotransformation is just altering of a drug by the body. Bioavailability is the percentage of the drug that makes it to systemic circulation.

[@Dr.BelloAliyu]

@@physiopathopharmaco4190 thanks u very much sir.. really appreciate

[@christin5569]

GOD'S Bless you...good

[@muygechlim6586]

Really helpful. Thank you 🙏

[@physiopathopharmaco4190]

So glad!

[@juliabl6471]

how is first pass metabolism or first pass effect different to the concept of enterohepatic circulation?

[@physiopathopharmaco4190]

First pass is breakdown of the drug by the liver before it reaches systemic. Enterohepatic circulation is circulation from the gut to the portal circulation to the liver back into the bile and back into the small intestine - so its circulating from the gut to the hepatic and back to the gut and back to the hepatic in a circular pattern - so much less of it reaches systemic circulation.

[@juliabl6471]

@@physiopathopharmaco4190 thank you so much!! Very helpful!

[@Mariam-nv1fk]

Nice but didn't understand the last qs ?👍🏻

[@Dravyaguna]

First pass effect causes lower amount of drug available for final action hence while shifting from IV to oral we have to increase the dose.

[@otpifree]

That you have to INCREASE the amount of drug given PO vs the original amount given via IV to account of the big loss due to first pass

[@CenobiteBeldar]

@@otpifree I might be wrong, but I'm guessing that if we were to give a high first-pass effect IV, it'd be considered over dose?

[@CenobiteBeldar]

@Montgomery Young So, it depends on how you administer it then. Just because it's IV, doesn't mean it's overdose.

[@suparnadhara5836]

Thanks sir

[@taiwovictoria1587]

Thank you!!

[@sayan2203]

the questions were good

[@diborazeleke5288]

Very nice🥰

[@lajasadi9406]

thank you so helpful

[@Jacqueline8]

YOU saved me :)

[@nizamudin55m12]

hi

[@deepakrawat_28vcsg78]

Ty

[@sokinahnasser6065]

AMAZING 🔥🔥🔥💯

[@797brm]

Great content!

[@zinenazm1641]

Why the answer of the questions doesn't b??

[@مرتضىنعمههادي]

So so so nice

[@physiopathopharmaco4190]

Thank you for the comment

[@clarity8296]

@@physiopathopharmaco4190 What do you use to draw you videos?

[@HEEM_SLEEPY]

Thanks :)

[@roronoazoro3204]

This video is so damn helpful

[@empty2thecore]

not me jumping around because i solved an equation that is taught in 8th grade

[@wraithdefilerjj1039]

The last question in the video, isn't the answer gonna be IV?

[@physiopathopharmaco4190]

The oral dose would have to be higher to compensate for the first pass effect.

[@ivynya29]

@@physiopathopharmaco4190 thanks. I missed the last part of the question too. I thought is was what should you expect as it pertains to the bioavailability. Yes, the oral dose will need to be higher in order to deliver the same effect as IV. But then depending on the drug the possibility of that will need to consider other parameters.

[@MsServando]

Why would the answer be "A"?

[@physiopathopharmaco4190]

You would have to give a higher oral dose because a portion of that oral dose will be removed by the liver before it makes it to systemic circulation.

[@MsServando]

Ohhhh, thank you so much...I completely misread the question

[@Sesinam2875]

I don't understand the question

[@DD-kc9lu]

Is this pedro pascal speaking?

[@ritlavkriraj9025]

How A is correct

[@Medicotopics]

Editer name !

[@SaadSaad-mb4py]

Fantastic

[@olha_]

As for the question at the end, depends on how intelligent your doctor is

[@JIMMYJREVIEWS_thaiM-A-F-I-A]

Can anyone help me with just 20 mg ? PLEASE!!!!

[@A_friend-pr6ji]

Hi, in this case, you should multiply 20*0,7*0,4, resulting in 5,6mg. Here the explanation: 70% of the drug reaches the liver (20*0,7 = 14mg, and 6mg are lost) From the 14mg that are in the liver, 40% goes into the bloodstream (14*0,4 = 5,6mg), and 8,4mg are lost (14*0,6 = 8,4). I hope this helps you.

[@Dravyaguna]

Nicely described

[@physiopathopharmaco4190]

🙏

[@arshusvlog9720]

@@physiopathopharmaco4190 i have a doubt sir. What about Acetamonophen / paracetamol ? As iv we give 1g but while change to oral we give only 650mg. Why?

[@arshusvlog9720]

@@physiopathopharmaco4190 also regarding CEFUROXIME. we give iv as 1.5g. But while switching to oral we prescribe 500mg only.. !!! Why sir?