What is the final concentration of a sodium chloride solution obtained by mixing 100ml of 0.9% w/v with 200 ml of 0.45%w/v and 300ml of 0.2% w/v.

Any help pls? :rolleyes:

good lord, this is really simple, just set up an equation.

100ml x 0.9% + 200ml x 0.45% + 300ml x 0.2% = 600ml x (X%)

Solve for X%.

good lord, this is really simple, just set up an equation.

100ml x 0.9% + 200ml x 0.45% + 300ml x 0.2% = 600ml x (X%)

Solve for X%.

What kind of equation is that?
(100x.9)+(200x.45)+(300x.2)=600ml????????????????? ??

What is the final concentration of a sodium chloride solution obtained by mixing 100ml of 0.9% w/v with 200 ml of 0.45%w/v and 300ml of 0.2% w/v.

Any help pls? :rolleyes:

Figure out the mass of each drug contained in each individual solution, masses are neither created nor destroyed. Add all those masses together, you now have a total amount of drug in the final mixture. Add all the volumes together. although on a technicality depending on the solvent or base liquid it may not be exactly 600 mls but since we are dealing with only water as a base liquid its 600 mls.

one thing to note, its good to think about the amount of drug in a volume as opposed to a concentration because lets just say you take 10 mls out of the 0.9% solution into the syringe to mix it with another. The concentration is the same in the syringe, but the amount of the drug is different, and the amount of drug in the syringe will change the concentration in the new solution

Figure out the mass of each drug contained in each individual solution, masses are neither created nor destroyed. Add all those masses together, you now have a total amount of drug in the final mixture. Add all the volumes together. although on a technicality depending on the solvent or base liquid it may not be exactly 600 mls but since we are dealing with only water as a base liquid its 600 mls.

one thing to note, its good to think about the amount of drug in a volume as opposed to a concentration because lets just say you take 10 mls out of the 0.9% solution into the syringe to mix it with another. The concentration is the same in the syringe, but the amount of the drug is different, and the amount of drug in the syringe will change the concentration in the new solution

good call

What is the final concentration of a sodium chloride solution obtained by mixing 100ml of 0.9% w/v with 200 ml of 0.45%w/v and 300ml of 0.2% w/v.

Any help pls? :rolleyes:

0.4% :meanie:

What kind of equation is that?
(100x.9)+(200x.45)+(300x.2)=600ml????????????????? ??

what's wrong? I always set up equations exactly as how the question logically flows. :) In this case, you got 3 solutions of different concentrations, which will give you 600 ml of what concentration? And you are solving for that "what". Basic understanding of mass and volume is assumed. ;)

what's wrong? I always set up equations exactly as how the question logically flows. :) In this case, you got 3 solutions of different concentrations, which will give you 600 ml of what concentration? And you are solving for that "what". Basic understanding of mass and volume is assumed. ;)

Please send me a picture so if I see you behind the counter I can run the other way.

The way Quiksilverr described the process is the correct way to perform the calculation.

100ml x 0.9% + 200ml x 0.45% + 300ml x 0.2% = 600ml x (X%)

.9+.9+.6=600 x (x%) makes no sense and does not compute......

0.4% :meanie:

Are you sure?:eek:

Are you sure?:eek:


yeah.. I am.

100ml x 0.9% + 200ml x 0.45% + 300ml x 0.2% = 600ml x (X%)



That is correct.

Please send me a picture so if I see you behind the counter I can run the other way.

The way Quiksilverr described the process is the correct way to perform the calculation.

100ml x 0.9% + 200ml x 0.45% + 300ml x 0.2% = 600ml x (X%)

.9+.9+.6=600 x (x%) makes no sense and does not compute......

looks like an old timer has gotten a little too old. :D My equation is correct. :)

looks like an old timer has gotten a little too old. :D My equation is correct. :)

Show me the math.

yeah.. I am.

So how many gms of NaCl are there in 600 ml?

Both ways come out exactly the same. Yeah, I'm so geeky for actually having done that but I didn't understand why xiphoid's equation wouldn't work.

good lord, this is really simple, just set up an equation.

100ml x 0.9% + 200ml x 0.45% + 300ml x 0.2% = 600ml x (X%)

Solve for X%.

This is how I was taught to solve these problems: just add up the individual components and come out with a total mixture. It's probably the most logical way of doing it.

Show me the math.



So how many gms of NaCl are there in 600 ml?

.004 x 600 = 2.4 grams

xiphoid's approach isn't excessive, excessive is how I used to approach questions where you have various concentrations and have to solve for quanities of each to produce a fixed volume of certain concentration.

I used to approach these using systems of equations before a teacher pointed out using alligation to save me the time.

Show me the math.


Which part of my simple equation don't you understand? It's really just simple logic equation of "total is the sum of all of its individual components", as confirmed by all the others in this forum. :confused:

This is how I was taught to solve these problems: just add up the individual components and come out with a total mixture. It's probably the most logical way of doing it.

yeah, thanks. My equation is a simple summation of all the components to solve for a single variable, and I thought it's very self explanatory.

Does anyone understand why Old Timer is not understanding my equation? Is it that hard to understand? :scared:

yeah, thanks. My equation is a simple summation of all the components to solve for a single variable, and I thought it's very self explanatory.

Does anyone understand why Old Timer is not understanding my equation? Is it that hard to understand? :scared:

Sure, when you make a calculation like this, it is safer to show your work and break down each component of the problem. If you were my student and you had to make a compound I would not let you do what you dud because it is faster or easier. The way Quicksilver described solving it is the only safe way. I know I'm being a pain in the a**, but I have seen to many errors over the years using the method you have described. It's so easy to end up off by a factor of 10 or a factor of 100. I had a student just this past week, do what you did and they used your formula and they were off by a factor of 10....

That's why I said show me the math..... Only It's Over gave the answer, just without any math so I asked if he was sure.

yeah, thanks. My equation is a simple summation of all the components to solve for a single variable, and I thought it's very self explanatory.

Does anyone understand why Old Timer is not understanding my equation? Is it that hard to understand? :scared:

Its not all that simple to understand. Yeah, its a one step problem but to understand what is conceptually going on, it is easier with my method. When you have a first time learner, the only way they are going to learn it is to conceptualize it. just my 2 cents

Its not all that simple to understand. Yeah, its a one step problem but to understand what is conceptually going on, it is easier with my method. When you have a first time learner, the only way they are going to learn it is to conceptualize it. just my 2 cents

Hmmm, maybe it's an asian thing. Math has always been like a natural language to me and very easy to understand and work with. Then again, maybe it's the difference in how little and much emphasis US and asian education system put on math. ;)

Sure, when you make a calculation like this, it is safer to show your work and break down each component of the problem. If you were my student and you had to make a compound I would not let you do what you dud because it is faster or easier. The way Quicksilver described solving it is the only safe way. I know I'm being a pain in the a**, but I have seen to many errors over the years using the method you have described. It's so easy to end up off by a factor of 10 or a factor of 100. I had a student just this past week, do what you did and they used your formula and they were off by a factor of 10....

That's why I said show me the math..... Only It's Over gave the answer, just without any math so I asked if he was sure.

Different people work the thought process differently. Students should use whatever thought process that works best and accurate for them, as long as the result is correct. I'll be more prone to error and not as efficient if I had to change my thought process into ones that's some one else's. My process worked best for me since I came out among the top of my class in both Pharm Calc and PK, and arrived at the answers faster than most. :D

Hmmm, maybe it's an asian thing. Math has always been like a natural language to me and very easy to understand and work with. Then again, maybe it's the difference in how little and much emphasis US and asian education system put on math. ;)

but lack the skills to communicate that across....

Touche my friend.

but lack the skills to communicate that across....

Touche my friend.

Math is the universal language. Learn it, speak it. :D

But agreed, asian education system focus way more on math and sciences. I was raised on that formula, at the expense of being more "well rounded". While I'm sure I will suck as a politician or a salesman, but let's just say no love lost there. ;)

Different people work the thought process differently. Students should use whatever thought process that works best and accurate for them, as long as the result is correct. I'll be more prone to error and not as efficient if I had to change my thought process into ones that's some one else's. My process worked best for me since I came out among the top of my class in both Pharm Calc and PK, and arrived at the answers faster than most. :D


Oh yeah? What's the extrapolated Cmax for Tobramycin 7mg/kg dose?

quick.

3 minutes elapsed.

6 minutes..

Oh yeah? What's the extrapolated Cmax for Tobramycin 7mg/kg dose?

quick.

no tobra dosing was taught. :D What's Tobra's Vd, infusion time, infusion method, number of doses given, how is it cleared? LOL

what you don't know those parameters off the top of your head? Shame on you zyvox.

3 minutes. :P

I'm a little disappointed..

you tell me what the VD is I'll tell you the infusion time is 60 minutes.
You tell me how it's cleared and I'll tell you that only 1 dose is given.

Infusion method???????? You tell me.

what you don't know those parameters off the top of your head? Shame on you zyvox.

3 minutes. :P


I was out cracking and eating walnuts. I'm off to the range. I expect answers when I get back.

I'm a little disappointed..

you tell me what the VD is I'll tell you the infusion time is 60 minutes.
You tell me how it's cleared and I'll tell you that only 1 dose is given.

Infusion method???????? You tell me.

Sorry, I'm not doing the looking up for you since you are not paying me to work for you. You want answers, you need to give me all the relevant parameters. And there are a lot of parameters. You are start off by looking up if it's one compartment model or 2. Mean while I gota go to my Business Management elective. See you when I come back, have fun researching. :D

I already know the answer with the parameters given. Just wanted to see how fast you can calculate it because you bragged about your pk and math prowess.

Oh yeah? What's the extrapolated Cmax for Tobramycin 7mg/kg dose?

quick.

Don't you either need a peak or trough or better yet patient parameters in order to solve this gem. I mean all i know is the long way to the answer.

also don't you need to know dosing interval and infusion time?

PS I'm not so bad at PK myself, and im not asian

Don't you either need a peak or trough or better yet patient parameters in order to solve this gem. I mean all i know is the long way to the answer.

no.

no.

are you going to leave me hanging? do you assume values of some of the variables?

I asked for extrapolated Cmax. What's the formula for Cmax?

Cmax = too high :)

EDIT: for traditional dosing!

Sorry, I'm not doing the looking up for you since you are not paying me to work for you. You want answers, you need to give me all the relevant parameters. And there are a lot of parameters. You are start off by looking up if it's one compartment model or 2. Mean while I gota go to my Business Management elective. See you when I come back, have fun researching. :D

its multiple compartment system. However you trap your calculations within a certain time window and you don't worry about number of compartments because you are only dealing with a single compartment.

its multiple compartment system. However you trap your calculations within a certain time window and you don't worry about number of compartments because you are only dealing with a single compartment.

that is true.

Cmax = too high :)

Even for extended interval...or even daily dose of a CF kid..


What's too high? What's the optimum bacteriocidal concentration of aminoglycoside against pseudomonas?

What's too high? What's the optimum bacteriocidal concentration of aminoglycoside against pseudomonas?

edited post =]
not too high for CF kid's daily dosing

pseudomonas where?

edited post =]
not too high for CF kid's daily dosing

pseudomonas where?


Location of pseudomonas would be irrelevant as far as determining the optimum bacteriocidal concentration. Location of infection on the other hand is important in determining the dose to attain certain peak.

Location of pseudomonas would be irrelevant as far as determining the optimum bacteriocidal concentration. Location of infection on the other hand is important in determining the dose to attain certain peak.

Hah, that's what i meant...psa INFECTION where?

You (royal) are really overdoing this. I'm grateful I had a applied kinetics rotation. We could start a patient on vancomycin with just weight and SCr. I'll be darned if those levels didn't come back correct to the tenth decimal place on a few occasions. Of course we'd refine the dose after viewing the levels, but population parameters were remarkably effective.

Dang, what good is all the PK education that's so convoluted with concepts and formulas that you guys can't see a clear cut day to day practical application of how to dose ?

You (royal) are really overdoing this. I'm grateful I had a applied kinetics rotation. We could start a patient on vancomycin with just weight and SCr. I'll be darned if those levels didn't come back correct to the tenth decimal place on a few occasions. Of course we'd refine the dose after viewing the levels, but population parameters were remarkably effective.


Thank you.

Now give me the answer.

I asked for extrapolated Cmax. What's the formula for Cmax?

Cpeak = [Dose/CL*T(infusion time)*(1-e^-kT)*e^-kt2 (1/2 hr in this case)]/1-e^-kt (dosing interval)


I am missing a clearance.

You (royal) are really overdoing this. I'm grateful I had a applied kinetics rotation. We could start a patient on vancomycin with just weight and SCr. I'll be darned if those levels didn't come back correct to the tenth decimal place on a few occasions. Of course we'd refine the dose after viewing the levels, but population parameters were remarkably effective.

who's royal?

Cpeak = [Dose/CL*T(infusion time)*(1-e^-kT)*e^-kt2 (1/2 hr in this case)]/1-e^-kt (dosing interval)


I am missing a clearance.

u can use a simpler estimate...
cmax = dose/vd

still dont have vd...but if we had a weight...you could estimate that as well with the population parameter...but no weight either.
b/c for traditional dosing, generally don't dose 7mg/kg of an aminoglyc unless its amikacin...

u can use a simpler estimate...
cmax = dose/vd

still dont have vd...but if we had a weight...you could estimate that as well with the population parameter...but no weight either. thus i stick to my final answer...b/c u don't generally dose 7mg/kg of an aminoglyc unless its amikacin... Cmax = too high

watch kidney function, dose adjust from there. no sense in dosing too low if it won't fight the infection. ****ing pseudomonas.

Cmax =28 ug/mL

Tobra has concentration dependent killing (loading dose) and plus if its a 1 time dosing, how much will it affect the kidneys.

Cpeak = [Dose/CL*T(infusion time)*(1-e^-kT)*e^-kt2 (1/2 hr in this case)]/1-e^-kt (dosing interval)


I am missing a clearance.

Granted I've only been out of school for a short while, but I've never seen anyone use these PK equations in practice. Those are great for class, but are too cumbersome for actual pharmacy work.

u can use a simpler estimate...
cmax = dose/vd

still dont have vd...but if we had a weight...you could estimate that as well with the population parameter...but no weight either. thus i stick to my final answer...b/c u don't generally dose 7mg/kg of an aminoglyc unless its amikacin... Cmax = too high


Why do you need the weight?

watch kidney function, dose adjust from there. no sense in dosing too low if it won't fight the infection. ****ing pseudomonas.

Cmax =28 ug/mL

Tobra has concentration dependent killing (loading dose) and plus if its a 1 time dosing, how much will it affect the kidneys.


Thank you.

who's royal?

Just a way of saying "you all, you guys, ya'll, you'ins, yousguys."

Loading Dose = Vd X Cmax

Cmax = LD/Vd

LD = 7mg/kg
Vd = 0.25L/kg

Cmax = 7mg/kg/0.25L/kg = 28mg/L = 28ug/ml.

So, for this patient, if t1/2 = 3 hours, what's the trough in 24 hours?

so, for this patient, if t1/2 = 3 hours, what's the trough in 24 hours?
0

Loading Dose = Vd X Cmax

Cmax = LD/Vd

LD = 7mg/kg
Vd = 0.25L/kg

Cmax = 7mg/kg/0.25L/kg = 28mg/L = 28ug/ml.


Now that's useful information. The simplicity is beautiful. I thought the same complicated way before I had applied kinetics and actually used it in practice.

0


Wrong. 0.109375 ug/ml :meanie:

0 hours - 28
3 14
6 7
9 3.5
12 1.75
15 0.875
18 0.4375
21 0.21875
24 0.109375!

:meanie:

Now that's useful information. The simplicity is beautiful. I thought the same complicated way before I had applied kinetics and actually used it in practice.


Aint it tho?

Tricky rational numbers.

Wrong. 0.109375 ug/ml :meanie:

0 hours - 28
3 14
6 7
9 3.5
12 1.75
15 0.875
18 0.4375
21 0.21875
24 0.109375!

:meanie:

I use your methodology to solve the 2nd question, argh. well certainly its lost all of its killing ability by that point so it might as well be 0.

I use your methodology to solve the 2nd question, argh. well certainly its lost all of its killing ability by that point so it might as well be 0.


You sound so sure.... Have you heard of PAE exhibited by aminoglycosides?

You sound so sure.... Have you heard of PAE exhibited by aminoglycosides?

Uh oh, my head hurts.

Uh oh, my head hurts.


:meanie: As quicksilver is googling feverishly..

:meanie: As quicksilver is googling feverishly..

You're blowing minds and shattering dreams. Informative discussion, thanks for this.

To whom ever said about making it over complicated -- true. Most hospitals have dosing protocols with just 2, maybe 3 parameters. They are designed for expediency and shooting for a window that's "close enough", not exact number. I see my ER preceptor whip out her deck of cards all the time. I have a feeling if I ask her about a new drug without a card, just a bunch clinical test parameters, she'll be stuck because she won't know how to work the math.

But for us students, that just won't fly on our tests. Professor will give you big fat 0 for it. And if I do the simple approximation route, it would give plenty of excuses for others to say it's not right and it's not close enough. :)

Anyone interested in an old exam question of this type? I can dig one up from my old exams, just for fun.

You're blowing minds and shattering dreams. Informative discussion, thanks for this.


And I'm just a pre-pharm...

You sound so sure.... Have you heard of PAE exhibited by aminoglycosides?

I have, but is it effective even after 1 dose? How about looking at the AUC/MIC ratio, how high does it stay even after D/C and for how long, does it provide a large enough ratio to effectively cover pseudomonas?

:meanie: As quicksilver is googling feverishly..

no googling, just studying Digoxin PK at the same time as this.


besides outside of you, we weren't born with this knowledge

I have, but is it effective even after 1 dose? How about looking at the AUC/MIC ratio, how high does it stay even after D/C and for how long, does it provide a large enough ratio to effectively cover pseudomonas?


You tell me.

How long does the PAE last?

To whom ever said about making it over complicated -- true.

But for us students, that just won't fly on our tests. Professor will give you big fat 0 for it. And if I do the simple approximation route, it would give plenty of excuses for others to say it's not right and it's not close enough. :)

Anyone interested in an old exam question of this type? I can dig one up from my old exams, just for fun.

Don't worry, I remember these exams quite well. I know it's not useful for you right now, but this simplified approach should prove useful on rotations.

besides outside of you, we weren't born with this knowledge

No one has implied that. I certainly didn't know this stuff, but I welcomed the revelation. I'm out of school and still learning.

But for us students, that just won't fly on our tests. Professor will give you big fat 0 for it. And if I do the simple approximation route, it would give plenty of excuses for others to say it's not right and it's not close enough. :)




Your professor can kiss my ass. Ok, so you need to get good grades and I'll give you that. But once you're out of school, saving lives is more important than worrying about tests. You'll thank the simplicity once you're out practicing.

no googling, just studying Digoxin PK at the same time as this.


besides outside of you, we weren't born with this knowledge


I'm not interested in you not knowing it today. But I am interested in you learning it that will benefit patient care in the future.

And I'm just a pre-pharm...

Even I can tell you know some stuff. Keep it up, you may be a pharmacy director one day!

Even I can tell you know some stuff. Keep it up, you may be a pharmacy director one day!


:meanie:

I'm just kidding... I aint no Pre-pharm. Why would anyone wanna be a DOP? It's a thankless job.

:meanie:

I'm just kidding... I aint no Pre-pharm. Why would anyone wanna be a DOP? It's a thankless job.

Sorry, it was a bad joke. I should use more emoticons. :smack:

No one has implied that. I certainly didn't know this stuff, but I welcomed the revelation. I'm out of school and still learning.
Don't take it personally, it was a jab for the google comment (he dishes it so i can assume he can take it, i'm sure he's been practicing long enough to understand a joke:D), I am happy to have the challenge of figuring this **** out. I try to use what i learn instead of just studying from test to test. Although I have probably wasted my night answering this. Thats how you learn.

You tell me.

How long does the PAE last?

I really don't know, thats why I asked. I don't think we learned it other then the effect does exist and the longer the dosing interval, the shorter the PAE. I didn't think that it would provide sufficient killing just from a single dose to kill Pseudomonas. Especially if you are concerned about developing resistance. From my understanding the longer you can keep AUC/MIC ratio high, the more sucessful a treatment will be. Unfortunately, I am not too sure beyond that. If the drug is eliminated, how long can the effects last? Perhaps I can google it later when I have a little more time:)

Your professor can kiss my ass. Ok, so you need to get good grades and I'll give you that. But once you're out of school, saving lives is more important than worrying about tests. You'll thank the simplicity once you're out practicing.

of course in real practice I'll just follow the hospital dosing charts just like my preceptor and go with a 'ball park figure'. But then again, you don't need a pharm.d to flip cards. Hell that preceptor is so old, they might not even have a real PK class in her days. :rolleyes:

:meanie:

I'm just kidding... I aint no Pre-pharm. Why would anyone wanna be a DOP? It's a thankless job.

That's ok...you get thanked too much on your current job! ;)

That's ok...you get thanked too much on your current job! ;)


are you stalking me!!! :eek:

Don't take it personally, it was a jab for the google comment (he dishes it so i can assume he can take it, i'm sure he's been practicing long enough to understand a joke:D), I am happy to have the challenge of figuring this **** out. I try to use what i learn instead of just studying from test to test. Although I have probably wasted my night answering this. Thats how you learn.



I really don't know, thats why I asked. I don't think we learned it other then the effect does exist and the longer the dosing interval, the shorter the PAE. I didn't think that it would provide sufficient killing just from a single dose to kill Pseudomonas. Especially if you are concerned about developing resistance. From my understanding the longer you can keep AUC/MIC ratio high, the more sucessful a treatment will be. Unfortunately, I am not too sure beyond that. If the drug is eliminated, how long can the effects last? Perhaps I can google it later when I have a little more time:)


Why does it have to kill pesudomonas? What does MIC stand for? So how long will the concetration be above MIC and how long will the PAE last? What is the mechanisim of action of Aminoglycoside?

are you stalking me!!! :eek:

lol...No...why? How many people kiss your a** today?

You're the one who stalks me!!!

lol...No...why? How many people kiss your a** today?

You're the one who stalks me!!!


no one kissed my ass today... it never happens. But I was highly annoyed with a vendor..

no one kissed my ass today... it never happens. But I was highly annoyed with a vendor..

Yeah...sure.

Highly annoyed, huh? Can you share the deets?

Yeah...sure.

Highly annoyed, huh? Can you share the deets?


I couldn't get some data. I get cranky when I can't get data.

I couldn't get some data. I get cranky when I can't get data.

I thought you had minions and secret agents embedded throughout the industry to collect data for you. Even ones who work for the competitor!

leave for just a moment and it's a whole new convo going on...

i wanted wt b/c i wouldve calculated a pop parameter...but yes I see now that 0.25 works just fine (ah, why did not I not remember that!). I still think 28 is high if you're starting a patient...you probably just want them over 20 for your pseudomonal infection if you're using extended interval. Under 30 is apparently okay...but I was on ID under a clinician who was pretty conservative about this.

as for length of PAE...no idea? is this established? i would guess at least up to 48 hours...i've seen patients with intervals extended to Q48 with EIDA

leave for just a moment and it's a whole new convo going on...

i wanted wt b/c i wouldve calculated a pop parameter...but yes I see now that 0.25 works just fine (ah, why did not I not remember that!). I still think 28 is high if you're starting a patient...you probably just want them over 20 for your pseudomonal infection if you're using extended interval. Under 30 is apparently okay...but I was on ID under a clinician who was pretty conservative about this.

as for length of PAE...no idea? is this established? i would guess at least up to 48 hours...i've seen patients with intervals extended to Q48 with EIDA


Why is 28ug/ml high? What's wrong with it? Why was your ID clinician conservative? Do you think it will reach 28ug/ml in vivo? Why would drug free period be perferred and help the patient?

I thought you had minions and secret agents embedded throughout the industry to collect data for you. Even ones who work for the competitor!


but sometimes I need the data now...at my finger tips. But I couldn't get though my usual means. It's fixed now.

Why is 28ug/ml high? What's wrong with it? Why was your ID clinician conservative? Do you think it will reach 28ug/ml in vivo? Why would drug free period be perferred and help the patient?

I was told why shoot for 30 when over 20 is fine. I'm not sure if it would reach 28 in vivo...but I'm guessing that it's a possibility. Drug free period in EIDA = still have efficacy...less toxicities.

I was told why shoot for 30 when over 20 is fine. I'm not sure if it would reach 28 in vivo...but I'm guessing that it's a possibility. Drug free period in EIDA = still have efficacy...less toxicities.


An hour infusion with short t1/2, I don't believe it will ever hit 30. You say less toxicities. But what's responsible for nephrotoxicity of AG? But there is another benefit of drug free period. What is it?

An hour infusion with short t1/2, I don't believe it will ever hit 30. You say less toxicities. But what's responsible for nephrotoxicity of AG? But there is another benefit of drug free period. What is it?

simple, wash out period. You need Cp < 2 mcg/ml for wash out. Hence the trough needs to be less than 2 for a signficant period of time to reduce nephrotox, which is perfect since AG has long PAE.

simple, wash out period. You need Cp < 2 mcg/ml for wash out. Hence the trough needs to be less than 2 for a signficant period of time to reduce nephrotox, which is perfect since AG has long PAE.


Ok, so what's another major benefit of wash out period?

simple, wash out period. You need Cp < 2 mcg/ml for wash out. Hence the trough needs to be less than 2 for a signficant period of time to reduce nephrotox, which is perfect since AG has long PAE.


How long?

An hour infusion with short t1/2, I don't believe it will ever hit 30. You say less toxicities. But what's responsible for nephrotoxicity of AG? But there is another benefit of drug free period. What is it?

toxicities = repeated high peaks?

another benefit = minimize adaptive resistance?

hah--i feel like i'm on rotation at sdn :p

toxicities = repeated high peaks?

No, toxicities come from sustained high troughs

another benefit = minimize adaptive resistance?

Exactly. Drug Free periods can enhance susceptibility.

hah--i feel like i'm on rotation at sdn :p

You wish your rotation was this interesting. :meanie:

How long?

we were taught at least 10-12 hours. That's it, which makes QD dosing pretty much the standard now a days.

Ok, that's all I gotta say about AG... look up David Nicolau's Once Daily AG article from early to mid 90's. An oldie but a goodie.

No, toxicities come from sustained high troughs



ah duh! peaks = efficacy...troughs = toxicity :smack:



You wish your rotation was this interesting. :meanie:

hah! i hope you don't really believe that.

hah! i hope you don't really believe that.

You'd be amazed at the stuff I believe in.

Why does it have to kill pesudomonas? What does MIC stand for? So how long will the concetration be above MIC and how long will the PAE last? What is the mechanisim of action of Aminoglycoside?

With a little bit of thinking, hopefully I am not far off...
I haven't really learned too much about it but I assume the PAE has to do with the fact that the drug enters the organism and effects the drugs ribosomal structure. It therefore can be inside the bacteria past the actual 5 half lives that is usually expected out of the drug? It may be circulating drug has been long cleared, but the drug is inside the organism hasn't been cleared and thus PAE?

Uptake and clearance from the organism are therefore important.
To keep the drug concentration above MIC will then provide ample drug to be absorbed by the bacteria. PAE must be effective for just as long as it takes the drug to penetrate the bacteria as a population and keep its numbers at bay. It must keep it at bay at least from the time that it drops below MIC until the next dose.

Am I at all correct, or is this really just an awful answer?

With a little bit of thinking, hopefully I am not far off...
I haven't really learned too much about it but I assume the PAE has to do with the fact that the drug enters the organism and effects the drugs ribosomal structure. It therefore can be inside the bacteria past the actual 5 half lives that is usually expected out of the drug? It may be circulating drug has been long cleared, but the drug is inside the organism hasn't been cleared and thus PAE?

Uptake and clearance from the organism are therefore important.
To keep the drug concentration above MIC will then provide ample drug to be absorbed by the bacteria. PAE must be effective for just as long as it takes the drug to penetrate the bacteria as a population and keep its numbers at bay. It must keep it at bay at least from the time that it drops below MIC until the next dose.

Am I at all correct, or is this really just an awful answer?


It is a fantastic answer. Good job.

With a little bit of thinking, hopefully I am not far off...
I haven't really learned too much about it but I assume the PAE has to do with the fact that the drug enters the organism and effects the drugs ribosomal structure. It therefore can be inside the bacteria past the actual 5 half lives that is usually expected out of the drug? It may be circulating drug has been long cleared, but the drug is inside the organism hasn't been cleared and thus PAE?

Uptake and clearance from the organism are therefore important.
To keep the drug concentration above MIC will then provide ample drug to be absorbed by the bacteria. PAE must be effective for just as long as it takes the drug to penetrate the bacteria as a population and keep its numbers at bay. It must keep it at bay at least from the time that it drops below MIC until the next dose.

Am I at all correct, or is this really just an awful answer?

I don't think people are really sure of the exact mechanism of PAE, and our professors didn't say either. I rationalized it as AG are irreversible binder of 30's subunit, aka suicide inhibitors. Every dead ribosome must be remade, and translation needed to make them incidentally require working ribosomes. There maybe be other MOA involved, but the rationalization seems to make sense.

we were taught at least 10-12 hours. That's it, which makes QD dosing pretty much the standard now a days.

and when can you NOT use QDay? (remember, QD is not legal anymore so it's good to practice using Daily or otherwise.)

and when can you NOT use QDay? (remember, QD is not legal anymore so it's good to practice using Daily or otherwise.)

renal patients? some won't wash out even at once a day dosing.

QD thing, yeah, but try tell that to the professors and physicians. :o

renal patients? some won't wash out even at once a day dosing.

QD thing, yeah, but try tell that to the professors and physicians. :o

I do tell physicians. And they rewrite. (yay for teaching hospitals and residents!)

renal patients? some won't wash out even at once a day dosing.


And...

renal patients? some won't wash out even at once a day dosing.

QD thing, yeah, but try tell that to the professors and physicians. :o

Why can't you tell it to them? It's the policy and violation means possible loss of accredidation. No accredidation, no hospital.

Why can't you tell it to them? It's the policy and violation means possible loss of accredidation. No accredidation, no hospital.

yeah, and ticking them off is a great way for an intern to get recommendation letters next year. :rolleyes: If the pharmacists and professors won't do it, I'm not sticking my neck out for their sorry asses.

And...

infants, ototox. synergistic dosing with another drug... elderly... many more. what exactly are you looking for? :confused:

yeah, and ticking them off is a great way for an intern to get recommendation letters next year. :rolleyes: If the pharmacists and professors won't do it, I'm not sticking my neck out for their sorry asses.


wow... I didn't learn it at school.... I don't want to jeopardize my rec letters.. I got high scores in math and Pk...

wow... I didn't learn it at school.... I don't want to jeopardize my rec letters.. I got high scores in math and Pk...

hey, if you want to risk your neck, go right ahead. Don't tell me to risk my neck when you sit there with nothing to lose. :sleep:

infants, ototox. synergistic dosing with another drug... elderly... many more. what exactly are you looking for? :confused:

burns.
enterobacter.
sepsis.

I couldn't remember the exact list and apparently don't have my kinetics notes on this computer, but per global rph:

" *Renal failure, CHF, Burn patients, cystic fibrosis, severe
hypotension, rapidly changing renal function. (Burn victims
and patients with cystic fibrosis usually have increased
rates of elimination. Patients with CHF or severe hypotension
will have decreased rates of elimination due to decreased
renal perfusion)"

It's not the complete list, I'll have to find that. But high dose once-daily AGs isn't always an option, even if it's the easiest way to do them.

yeah, and ticking them off is a great way for an intern to get recommendation letters next year. :rolleyes: If the pharmacists and professors won't do it, I'm not sticking my neck out for their sorry asses.

are you planning on getting LoRs from MDs?

pregnancy

pregnancy

and immediately post bebe.

are you planning on getting LoRs from MDs?

no, but you think making an MD miserable will make my preceptor taking his orders have a pleasant day? Of course she will then writes a great rec letter about how great I am as a team player.

My philosophy might be a bit different than yours: when you are the lowest on the totem pole, don't stick your neck out and tell others what to do, let your work speak for itself. Make lots of allies, and don't be making enemies until you are up a few rungs. :rolleyes:

no, but you think making an MD miserable will make my preceptor taking his orders have a pleasant day? Of course she will then writes a great rec letter about how great I am as a team player.

My philosophy might be a bit different than yours: when you are the lowest on the totem pole, don't stick your neck out and tell others what to do, let your work speak for itself. Make lots of allies, and don't be making enemies until you are up a few rungs. :rolleyes:

Have you actually TRIED to suggest the QD thing to a physician? How about your preceptor?

it's not making them miserable. And if it's a resident, they know they're learning and they need to learn it right. That's why we have to call on the "Kayexalate 30 mmol NG x 1" and clarify they meant grams, etc.

And you can bring it up diplomatically - or even in a joking manner. Just because you're lowest on the totem poll doesn't mean you don't have anything to contribute.

I work in a Level 1 trauma center with an established ER pharmacy program. As a student I've been known to go around with a ruler and threaten to rap knuckles when orders don't get signed. You develop that relationship with the other members of the team and they know it isn't personal.

Have you actually TRIED to suggest the QD thing to a physician? How about your preceptor?

no, why? Isn't being told by an intern just once bad enough? I know if I'm the MD I'll be irritated.

Look, you guys obviously don't mind being risk taking moral crusaders, especially when its telling someone else to take all the risk. Hey, that's great for you guys, but I'm going to keep my head down until I'm not the little fish in the pond any more. :D

and my LoR from my EM preceptor mentioned my work as a team player and diplomatically getting changes. As well as my great relationships with the nurses, techs, and physicians.

Cowering in the corner doesn't help - you'll be lucky if they remember you.

it's not making them miserable. And if it's a resident, they know they're learning and they need to learn it right. That's why we have to call on the "Kayexalate 30 mmol NG x 1" and clarify they meant grams, etc.

And you can bring it up diplomatically - or even in a joking manner. Just because you're lowest on the totem poll doesn't mean you don't have anything to contribute.

I work in a Level 1 trauma center with an established ER pharmacy program. As a student I've been known to go around with a ruler and threaten to rap knuckles when orders don't get signed. You develop that relationship with the other members of the team and they know it isn't personal.

Well, if that works for you, more power to you. But that's not me. I work in the ER too, and I've seen MD chew my preceptor out enough about needing her approval for antibiotic access (per hospital policy) to the point that she was red in the gills and ruminated all day. So no, I know how things are, and there's no way I'm going to try your stuff, no offense.

I brought up the ER because you mention working in an ER pretty regularly. I was just letting you know I'm not at a 30-bed community hospital where the doctor is God.

and my LoR from my EM preceptor mentioned my work as a team player and diplomatically getting changes. As well as my great relationships with the nurses, techs, and physicians.

Cowering in the corner doesn't help - you'll be lucky if they remember you.

Oh, they'll remember me, I'm only 1 of 3 interns manning the ED sat, and the only one who did a poster so far, and I haven't offended anyone in the department yet which can't be said for one of the interns.

I brought up the ER because you mention working in an ER pretty regularly. I was just letting you know I'm not at a 30-bed community hospital where the doctor is God.

Then i miss understood why you brought it up. My apologies.

no, why? Isn't being told by an intern just once bad enough? I know if I'm the MD I'll be irritated.

You can't transpose your hypothetical reaction as a hypothetical physician without having been in that situation somehow. Just try it once and see what happens. Notice I mentioned you bringing it up to your preceptor, too, not just to the MD.

And earlier you mention professors, too. Many professors don't work in the field regularly and may not be aware of the changes.

You can't transpose your hypothetical reaction as a hypothetical physician without having been in that situation somehow. Just try it once and see what happens. Notice I mentioned you bringing it up to your preceptor, too, not just to the MD.

And earlier you mention professors, too. Many professors don't work in the field regularly and may not be aware of the changes.

no. Let's agree to disagree. The best course of action obviously differ depends on the individual and what each person deems to be more important.

In my current situation, I deem getting along with everyone at work and securing rec letters to be most important to me. To stick my neck out for this just has too little potential gain and too much potential cost, making it a needles risk to take. Sorry, when it comes to my future I play it safe, because nobody is going to look out for my ass except myself.

This is not intended to say what others choose to do is irrational. Just to each his own. :thumbup:

no. Let's agree to disagree. The best course of action obviously differ depends on the individual and what each person deems to be more important.

In my current situation, I deem getting along with everyone at work and securing rec letters to be most important to me. To stick my neck out for this just has too little potential gain and too much potential cost, making it a needles risk to take. Sorry, when it comes to my future I play it safe, because nobody is going to look out for my ass except myself.

This is not intended to say what others choose to do is irrational. Just to each his own. :thumbup:Don't worry. It's an Asian thing. :meanie: A few thousands of years of civilization and viola! --> automatic totem poles.

Honestly, I think it's a cultural thing.

Being a 3rd gen American and a 1st gen professional student, I don't try to follow other people, because if I did, it would make following difficult since there aren't very many people like me in the first place. What I've found to work is the following: rationalism, adhering to a standard of ethics, and unbiased generosity.

So, if I felt that said MD or resident or preceptor needed to update their sig codes, then I would tell them sincerely and politely, because that would be rational (staying current makes sense), ethical (in terms of patient care), and addressed appropriately (without being snide or uppity).



It's the middle of the night... and I have a test tomorrow that I keep studying for back and forth. :p

burns.
enterobacter.
sepsis.

I couldn't remember the exact list and apparently don't have my kinetics notes on this computer, but per global rph:

" *Renal failure, CHF, Burn patients, cystic fibrosis, severe
hypotension, rapidly changing renal function. (Burn victims
and patients with cystic fibrosis usually have increased
rates of elimination. Patients with CHF or severe hypotension
will have decreased rates of elimination due to decreased
renal perfusion)"

It's not the complete list, I'll have to find that. But high dose once-daily AGs isn't always an option, even if it's the easiest way to do them.

From my notes: Edema, ascities, post partum, surgery all increase Vd. Sepsis decreases Vd
Increased elimination occurs in burn patients and cystic fibrosis patients. And populations with renal issues obviously have decrease in CL.

one of the nice things about the hospital that i work at is that all physician orders are put into the computer by the physician. They don't even have the opportunity to use those abbreviations.

Don't worry. It's an Asian thing. :meanie: A few thousands of years of civilization and viola! --> automatic totem poles.

Honestly, I think it's a cultural thing.

I'd agree that there is a cultural component to it. I was born in China, my family like so many other asian families, came to this country with basically nothing, and we prospered by studying hard, work hard AND staying out of trouble with the natives. The down side of our ways is that we are not a politically active ethnicity, but so far that hasn't stopped us from becoming a prosperous one. :)

As the old chinese saying goes: mountains and rivers are easy to alter, people's nature is hard to change. I largely agree with this -- people don't change (most of the time). Of course, then I also agree with the american old saying "it's a free country", and they can do things the way they want. :D

First Id like to say Hi to everyone as this is my 1st post. Second...boy o boy am I glad I didn't go to a proffesional program right out of undergrad. I was such a kid. Most of you here seem severely lacking in the social skills department. Having been out of my undergrad for the past 4 years and being part of the "real" world (working full time, lay offs, etc...), seems to now have been a good decision. Many of you in this thread, through no fault of your own of course, come off as naive and immature.

My advice is to *realize* everyone around you is human and to put away these ideas about how you SHOULD talk to people of various position. Treat everyone and i mean everyone the same. Respect them equally because you all share a common humanity not because of title or position, unless they give you reason not to. By not being honest with people you are disrespecting them. Don't forget that.

This is a great forum very glad I found it. Hope you all have a great rest of the the day. :D

First Id like to say Hi to everyone as this is my 1st post. Second...boy o boy am I glad I didn't go to a proffesional program right out of undergrad. I was such a kid. Most of you here seem severely lacking in the social skills department. Having been out of my undergrad for the past 4 years and being part of the "real" world (working full time, lay offs, etc...), seems to now have been a good decision. Many of you in this thread, through no fault of your own of course, come off as naive and immature.

My advice is to *realize* everyone around you is human and to put away these ideas about how you SHOULD talk to people of various position. Treat everyone and i mean everyone the same. Respect them equally because you all share a common humanity not because of title or position, unless they give you reason not to. By not being honest with people you are disrespecting them. Don't forget that.

This is a great forum very glad I found it. Hope you all have a great rest of the the day. :D

not be a dick, but you are being a hypocrite. You post how to treat everyone equally but at the same time you talk down at us as if we were children that do not know anything. I thought we are all equal?

I thought we are all equal?

All animals are equal, but some animals are more equal than others. George Orwell, Animal Farm.

2 things,

1. the original eq'n by xiphoid was not only correct, I can't think of a more logical/simple way to approach the question?

volume*conc + volume*conc + volume*conc = total volume * total conc

I didn't even read through the rest of this thread and can't believe a pharmacist would dispute this :eek:.

2. Omega sub D over 2 = Omega sub Z + Epsilon

http://www.noob.us/humor/conan-and-jim-carrey-talk-quantum-physics/

not be a dick, but you are being a hypocrite. You post how to treat everyone equally but at the same time you talk down at us as if we were children that do not know anything. I thought we are all equal?

No, I said treat everyone the "same". And maybe you confused "respect equally" with "being" equal? Scope of my post was social interactions, not "anything"! It was meant to be helpful. :hello:

All animals are equal, but some animals are more equal than others. George Orwell, Animal Farm.

Awesome book. I loved it. Easy read. I recommend it. Russian Revolution.

No, I said treat everyone the "same". And maybe you confused "respect equally" with "being" equal? Scope of my post was social interactions, not "anything"! It was meant to be helpful. :hello:
You have not answered how you can say what you said without being in the least bit hypocritical? How do you respect people equally when you talk down at them? Is that not counterintuitive? We are supposed to be equal.

How can you respect someone equally if you don't view them as being at least your equal? the use of the word "anything" in that context means "anything about communication".

I apologize for my rudeness, I enjoy philosophy. I enjoy these convos, even though your intentions are good, if your message is contradictory, what message do you really deliver?

Anyways, no hard feelings, welcome to the board. Welcome to pharmacy. The profession for Big Egos that didn't make it to medical school.:D:p

Welcome to pharmacy. The profession for Big Egos that didn't make it to medical school.:D:p

:welcome:

Awesome book. I loved it. Easy read. I recommend it. Russian Revolution.


You have not answered how you can say what you said without being in the least bit hypocritical? How do you respect people equally when you talk down at them? Is that not counterintuitive? We are supposed to be equal.

How can you respect someone equally if you don't view them as being at least your equal? the use of the word "anything" in that context means "anything about communication".

I apologize for my rudeness, I enjoy philosophy. I enjoy these convos, even though your intentions are good, if your message is contradictory, what message do you really deliver?

Anyways, no hard feelings, welcome to the board. Welcome to pharmacy. The profession for Big Egos that didn't make it to medical school.:D:p


if you honestly consider what I said "talking down to you", be prepared to be "talked down to" much much more once you start your career. Otherwise you should look at it as honest advice which you may or may not enjoy hearing.

My advice is to *realize* everyone around you is human and to put away these ideas about how you SHOULD talk to people of various position. Treat everyone and i mean everyone the same. Respect them equally because you all share a common humanity not because of title or position, unless they give you reason not to. By not being honest with people you are disrespecting them. Don't forget that.

Some physicians can be downright vindictive. I wouldn't act in deference to their professional prestige if the issue concerns patient safety, but if the advice is not well received then you should reconsider your approach. I've offered well-intentioned advice and have been utterly burned. Intentions count little in the healthcare hierarchy. Choose your battles wisely, coordinate your attacks precisely, seek timely reinforcements, and prepare for total war.
:boom:

Some physicians can be downright vindictive. I wouldn't act in deference to their professional prestige if the issue concerns patient safety, but if the advice is not well received then you should reconsider your approach. I've offered well-intentioned advice and have been utterly burned. Intentions count little in the healthcare hierarchy. Choose your battles wisely, coordinate your attacks precisely, seek timely reinforcements, and prepare for total war.
:boom:

As an intern, I just play chicken and avoid battles all together. Some battles are just not worth fighting, even if you win the battle, you lose the war. :D When you are stronger than the enemy, attack them; when you are equal in strength, you can offer battle; when you are weaker, you can avoid -- sun tzu.