How to modify bioavailability of drug?

[myvow]

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i i think acidic medium =stomach, so drug interaction can be applied in this case?using some drug to alter the motility rate of gastric emptying?

ii I think the drug is OK because extraction ratio is not too high,but I have no idea to explain in detail

iii it must change the rote of administration because the drug will be digested by gastric acid.


can anyone give me an advice if my answer is valid?
Thank you very much

 

[Chriskahn]

i i think acidic medium =stomach, so drug interaction can be applied in this case?using some drug to alter the motility rate of gastric emptying?

ii I think the drug is OK because extraction ratio is not too high,but I have no idea to explain in detail

iii it must change the rote of administration because the drug will be digested by gastric acid.

can anyone give me an advice if my answer is valid?
Thank you very much

i. I wouldn't mess with drug interactions, it could lead to other problems. I think what they are looking for might be different dosage forms. Think sustained release versus immediate release. A sustained release dosage form wont be effected by stomach acid since it wont be released until it makes it to small intestine, preserving its therapeutic dose.

ii. Since the drug has a hepatic extraction ratio of 50%, no matter how many grams of drug is given, 50% of it will get extracted. This means that a constant proportion of drug gets eliminated, which means its a first order process, which means it is concentration dependent. So since drug B has 50% extraction ratio, all you have to do is double the concentration of the drug by doubling the dose administered to achieve the desired therapeutic concentration.

iii. Your answer sounds valid to me.


I'm surprised you are already getting into PK (pharmacokinetics) as a pre-pharmacy student. Are you taking some sort of pharmacy prep course? At my school PK wasn't taught until second year of pharmacy school (they changed it to first year this year actually) But hey you will be a step ahead of the game so its a good thing.

 

[PharmNerdMatt]

i. Also consider something like Enteric Coating.
ii. See Chriskahn's answer. This is how we handle first pass in real life.
iii. yep. Have to give them IV.

This is a lot like things we talked about in Medicinal Chemistry (senior undergraduate class). Also, are we doing your homework? I really hope it isn't a take home test.

 

[myvow]

i. I wouldn't mess with drug interactions, it could lead to other problems. I think what they are looking for might be different dosage forms. Think sustained release versus immediate release. A sustained release dosage form wont be effected by stomach acid since it wont be released until it makes it to small intestine, preserving its therapeutic dose.

ii. Since the drug has a hepatic extraction ratio of 50%, no matter how many grams of drug is given, 50% of it will get extracted. This means that a constant proportion of drug gets eliminated, which means its a first order process, which means it is concentration dependent. So since drug B has 50% extraction ratio, all you have to do is double the concentration of the drug by doubling the dose administered to achieve the desired therapeutic concentration.

iii. Your answer sounds valid to me.


I'm surprised you are already getting into PK (pharmacokinetics) as a pre-pharmacy student. Are you taking some sort of pharmacy prep course? At my school PK wasn't taught until second year of pharmacy school (they changed it to first year this year actually) But hey you will be a step ahead of the game so its a good thing.

Thank you very much!
I am not studying in United States😀

 

[myvow]

i. Also consider something like Enteric Coating.
ii. See Chriskahn's answer. This is how we handle first pass in real life.
iii. yep. Have to give them IV.

This is a lot like things we talked about in Medicinal Chemistry (senior undergraduate class). Also, are we doing your homework? I really hope it isn't a take home test.

Don't be worry, it's just a past exam paper.
I am prepared for the final exam on this friday