Vancomycin Dosing

 

hi this is Elissa critical care pharmacy

resident and my clinical pearl today

we'll cover vancomycin monitoring and

the transition from traful new

monitoring to monitoring of the AUC or

area under the curve briefly vancomycin

Vancomycin

is a glycol pop type antibiotic and it's

been FDA approved now for more than five

decades banco Meissen is used mainly for

broad-spectrum gram-positive coverage

especially of more resistant

microorganisms such as

methicillin-resistant Staph aureus the

main side effect I want to pull out is

nephrotoxicity and this generally occurs

when vancomycin is used at higher doses

so when we target a trough of 15 to 20

when vancomycin is used for a long

period of time or when a patient is also

receiving other nephrotoxic medications

such as pepper cilenti's of Actium we're

all familiar with vancomycin trough only

monitoring as this is really what we've

done in recent years targeted trough

anywhere from 10 to 20 but typically 15

to 20 when we're using Vanko for more

severe infections we wait until

steady-state to check the trough so

before the third to fifth dose and then

based on that we adjust our dose

accordingly and this really represents

where practice will be changing as we

will have new guidelines released

shortly that will recommend switching

from trough monitoring to monitoring of

the area under the curve to minimum

inhibitory concentration ratio so taking

Pharmacodynamic Parameters

a bigger look at what this exactly means

we know that antibiotics in general each

have a pharmacodynamic parameter that

predicts their effectiveness so for some

antibiotics like our amino glycosides

and our quinolones we want to target a

high peak on the other hand for a beta

lactam so we want to keep the

concentration above the m.i.c for as

long as we can and that provides the

justification for why we get zosyn as an

extended infusion thank you my son on

the other hand doesn't really quite fit

either of these it's going to be a you

see above em I see dependent meaning

that really we're looking at overall

exposure to vancomycin we're shooting

for an

you see above em I see of 400 to 600 and

this is over a 24-hour period briefly

want to touch on a couple of assumptions

that we make with the EUC the MSE

monitoring and the first is that this is

really specifically being used for staph

aureus so it doesn't really apply to

other types of bacteria the second is

that we're assuming that the minimum

inhibitory concentration of the staph

species is 1 to vancomycin in most cases

that's going to be true but just kind of

keep in the back of your mind that there

can be cases where the m.i.c creeps up

so if we see a higher MSE of 2

indicating more vancomycin resistance as

you can imagine it's going to be a lot

harder to achieve an adequate AUC above

m.i.c ratio so key point to know in

those cases is that typically we'll end

up switching patients to an alternative

like linezolid or daptomycin once we see

that susceptibility and an M IC of 2 to

Vanko now how are we actually going to

AUC Monitoring

carry out the EC monitoring there are a

couple of different ways the one that I

want to focus on for the purpose of this

clinical pearl is peak and trough

concentrations because this is primarily

what we'll be using we can check a peak

one to two hours following the end of

our Vanko infusion and then we'll

continue trough monitoring and this will

allow us to extrapolate the area under

the curve again we want 400 to 600 and

we don't want to push the AUC too high

because that increases our risk of

causing acute kidney injury just like

trough monitoring this will be done at

steady-state we can either do it within

a dosing interval or for practicality

more often than not we're doing this

around one dose since we don't have to

wait as long between levels so in

summary practice will be changing from

traffic only monitoring to monitoring at

both the peak in the trough with

vancomycin and this will allow for

estimation of the area under the curve

which we know is a better predictor of

ankle Meissen effectiveness and toxicity

as well and then kind of the kicker here

we're finding that those lower trough

values of ten to fifteen actually tend

to produce an AUC within our goal range

so when we targeted those higher troughs

at fifteen to twenty in recent years we

were probably exposing patients to more

Vanko than they needed and predisposing

them to more acute kidney injury as a

result and that summarizes my first

clinical pearl please reach out to me if

you have any questions and thanks for

listening

Trough lowest level before the next dose

Dosing patient by level when they have bad renal function

Introduction

hello and welcome to another video at

the pharmacist Academy whoa how to

monitor patients on vancomycin

now vancomycin is a very important

antibiotic simply because it has

potential to cause renal failure

now this renal failure is usually

preventable by monitoring the patient's

trough levels so in this video we are

going to discuss how to dose these

patients initially how to modify the

doses and how to monitor these patients

while they're taking the medication

Background of Vancomycin

now to begin I wanted to provide a

little background of vancomycin

vancomycin is a glycoside antibiotic and

it mostly covers gram-positive organisms

right includes an Mrs a B number one

concern and the number one use really

for vancomycin and Clostridium difficile

infections c diff in that case we use

the oral form of vancomycin now the

medical users are listed here for your

information and vancomycin is usually

used also when a patient has a

penicillin allergy so they can get let's

say any type of penicillin

cephalosporins or whatever the case is

and you need to cover gram positive then

vancomycin is usually your go-to

medication now once these patients are

Initial Dosing

started on vancomycin they are usually

start on the initial dosing right and

very few patients received a load and

dose of this medication now that those

are frequency is based on actual body

weight okay regardless if the patient is

obese or not and renal function also

plays a row now for patients who are

critically ill right like patients with

endocarditis patients with meningitis

they usually receive an IV loading dose

before they start the maintenance dose

and this is simply to increase the

amount of vancomycin and the blood right

away

and then the patient will receive you

know in amman maintenance doses of the

medication and this is usually done in

the IDI or the emergency room they give

the patient a one-time dose of this

medication and then they send the

patient up to the unit now as I

mentioned already you use actual body

weight for obese patients also now those

modifications after the initial dosing

are based on the trough levels which I

will talk about a little bit more as we

go

institutions may also create something

something known as a docent table for

Dosing Table

the initial dose and of vancomycin and

as you can see here they have the actual

body weights here right and depending on

the cran and Clarence you get a dose

plus of frequency so every institution

may have their own way of doing this but

they usually follow the same idea of you

Dosing Schedule

know the same dosing right like 15 to 20

milligrams per kilogram and it could be

given every eight hours every 12 hours

or every 24 hours

Trough

now once the patient is started on this

initiative those what you want to do is

monitor the patient right because we

want to prevent any renal toxicity from

the medication so we look at something

known as a trough now a trough level is

simply the lowest level of blood

concentration of the medication right

before the next dose so as soon as you

give a dose here right the amount of

vancomycin and the blood increases right

away but over time it starts to drop

okay now once it gets here this is the

lowest point of guy right the lowest

amount of vancomycin you had in the

blood before you gave the second dose

and brought it back up now when it's up

here it's a peak as you can see here now

the trough is usually taken 30 minutes

to one hour before the fourth dose of

the vancomycin is given and this is

simply done because we want to make sure

the medication is in steady state and I

usually take

about three doses for us to achieve that

now once you're in study state you could

take the vancomycin 30 minutes of one

hour before the next dose right well

there's the four of those the fifth dose

the six those you could get the loved

one it's appropriate but we usually want

to do it right before the fourth dose

now the dose to be given after the

trough right so if you take the tribe

you draw the blood level right but right

after you draw the blood level you can

actually give a dose okay but in certain

cases they may hold the dose because

they are really concerned at the trough

level might be a little higher it might

be a little higher so the more

medication the more vancomycin the

patient get and the patient is unable to

clear it the higher the trough levels

will be and that will increase the

patient's chance of developing renal

toxicity now the chart maybe taken

earlier if patient has unstable renal

function so you don't even need to wait

so it's steady state right the patient

has renal like bare renal function you

could check the trough earlier you don't

need to give the patient three doses

first in order to check right you could

do this and this is what we call dose

and a patient by level I'm gonna go

through some patient cases as we go on

so you understand is more now those

modifications once again this is usually

done right you only do those

modifications based on the trough level

and a trough level for skin and

soft-tissue or other infections are

usually 10 to 15 and for you know sepsis

bacteremia st my light is and the car

diet is that's all 15 to 20 now based on

the trough level the dose should be

increased if patients trough is lower

than the target level right the dough

should be decreased if patients Chavez

higher than the target level if patients

renal function is worsening all right so

that those could be skipped in this case

also remember that

you don't need to give the dose if you

think that the renal function may worsen

or it's not that stable now when you're

monitoring patients on vancomycin or

before you verify a vancomycin order or

you're waking up a patient on vancomycin

before you go around and you want to

consider each of the following the

trough already discussed but we're gonna

go through each one of this so the way

Weight

those are frequency increases the the

weight right it proportionally increases

with the weight they go up at the same

time right they both go up so example

assuming the age and renal function is

the same in this case right patient a

may receive patient a is 50 kilos and

will receive one gram every 12 hours of

vancomycin but patient B is 100 kilos I

may receive 1.5 grams every 12 hours

right so because of the weight

difference the patient weighed more

received more of the vancomycin and

sometimes the frequency you know that

patient can also receive it more often

so take that into consideration age also

plays a role when it comes to those in

these patients so frequency and/or dose

make the crease with increased age and

this is because we tend to associate all

the patients with sub-optimal renal

function right they don't have the best

kidneys they may not be clearing this

medication now assuming the weight is

the same patient a is 70 years old and

will receive one gram once daily and

patient B is thirty years old and will

receive one gram every 12 hours okay now

Serum Creatine

we also want to monitor these patients

right and when we're monitoring these

patients we look at the serum creatinine

so before you verify let's say a

vancomycin order you want to look at the

some crowning right as the most

important thing you want to look for now

you want to make sure you evaluate the

some cran and trend don't just look at

the current level so let's say today was

January 4th

and I see this level of 0.8 I'm not just

gonna focus on 0.8 I'm not gonna just

assume this is the baseline you have to

look at the trend to notice the baseline

right so the patient's baseline was

actually 0.3 when they first came in and

as you can see is slowly increasing

right now once you notice that it's

increasing you could use your clinical

judgment

okay the renal function might be

worsening so maybe when this patient is

starting this vancomycin right they

shouldn't be too aggressive right they

should be a little cautious because the

renal function might worsen now if a

renal function is worsen and consider

lowering the dose and or just and/or

adjusting the frequency if you have

concerns of a Quirino toxicity consider

obtaining a vancomycin trough okay and

just to make sure the trough is in

raised before you give the next dose so

that's when you're gonna hold the dose

until you get the results of the trough

and also you could assess patients

you're an output

okay that's possible if the patient is

not making a lot of urine you're

probably not clearing the medication

either so regardless of what you get for

let's say the some Cayenne and or cran

and Clarence if the patient is not

making urine

you should probably dose adjust also

decrease the dose decrease the frequency

if you have to please note that the

serum creatinine trend rule also applies

for cran and Clarence also like before

you verify the medication or you're

monitoring these patients look for the

indication as this will help you

determine the duration of the vancomycin

also you could see the cultures that was

taken um that will also help you when

you're monitoring or working of these

patients for rounds alright just check

to see if you're using the vancomycin

for the right purposes right for the

right bug and that's all you really have

to do now I have some patient cases here

Patient Case 1

and these cases will allow you to like

develop the thought process when you're

evaluating a patient on vancomycin okay

well before you verify a vancomycin

order this is a male patient we have the

weight and the age here for you this is

the right GFR let's just say cran and

Clarence and Assam cannon and this

vancomycin was started on April 1st

right and this is the dose here 1.25

grams every 12 hours to be infused over

one hour the indication is sepsis and

the patient has received one to three

doses now based on the patient's weight

and age I agreed at one point to five

grams q 12 is appropriate right it's not

always think of one gram q 12 as kind of

like the baseline for like that the

average patient in terms of age and

weight one gram q 12 okay and just work

from there so this patient is you know

younger a little heavier so yeah they

could definitely get one point two five

grams every 12 hours

okay now the dose of frequency is

appropriate like I said the trough is

due before the fourth dose right in this

case on April 2nd and they're gonna aim

for 15 or 20 because the patient is

septic and you want to monitor the same

crannis since it's increased slightly

right 0.9 it's a 1.1 it may not be

significant now right but just keep your

eye on it if it goes up it's a chance it

might go up a little bit more right so

just just monitor for that so for

Patient Case 2

patient case 2 as we see right away you

know the renal function is very poor

this is a female he has the weight the

age and this patient was starting

vancomycin right it started on for one a

prefers vancomycin one gram every 24

hours for pneumonia now it's a good try

before the April 4 dose and they got 9.4

the initial dose could have also been

oh dear oh but not too old they yeah

yeah kind of heavy right you're kind of

on the high end in terms of the weight

and the renal function right when they

started on for one was 3.7 so just taken

taken into consideration just the renal

function and the age alone right the

serum cannon you could have probably

done 750 also but as you can see the

patient's renal function started to

improve a little bit so the trough was

low now based on the trough what do you

want to do you could do you can increase

the dose

alright the patient's renal function is

actually Inc like improving you can

increase the dose to 1.25 grams all 1.5

grams every 24 hours alright but you

want to be more conservative as a

pharmacist and I would probably go with

the 1.25 grams

once daily in this case right and just

monitor the renal function the renal

function goes back up the next day you

probably want to decrease that back to

one gram all right just to be

conservative is if it keeps dropping

leave it at 1.5 grams but if a job so

significantly let's say it's less than

less than one right then you just you

have more room right so you know

increase the dose if you need to patient

Patient Case 3

case 3 is a female here's the way age of

levels are here looks okay in terms of

the trend the patient started on a

prefers vancomycin one gram every 24

hours to be infused over one hour this

was a skin infection it's in the trough

before the April fourth dose and the

level was 18.9 so the initial dose is

acceptable in this case right based on

the patient's weight and age you know

patient is you know old you're not that

heavy right and the arena function is

not that great alright so you can just

give them one gram just once daily the

frequency is also okay based on the

renal function trough is high for the

indication

a skin infection if it's not really

touching the bone we usually aim for 10

to 15 the trough is high for that

indication so those could be decreased

around there for patient case four we

Patient Case 4

have a male who's 67 kilos 81 years old

receiving vancomycin 750 once daily to

be infused over one hour for skin

infection and here we have the serum

creatinine Tran and it seems like it's

increasing so it seems like this patient

is experiencing an acute kidney injury

and it may be appropriate to those this

patient buy levels in other words we

want to obtain a random vancomycin level

before each dose so the patient got the

four four dose right for the four five

those you wanna check the trough right

you want to get the level before you

give that dose but what we're gonna do

since the patient's renal function is

not doing good let's say it increased

also the next day we want to hold that

those on so we get the level back once

we get the level if the level is in

range all right then we might skip the

dose all right we don't need to give it

if it's elevated elevated we might we

definitely are gonna skip the dose if

it's low we are gonna give the dose okay

if it's in range you really have a

option to either hold it or actually

give it really depends you know if you

really feel like the renal function is

gonna improve or just check the level

alright just check the level of the

level is in range and you know the

patient is making urine or whatever the

case is all right you got to leave you

got to use your clinical judgment in

that case there's no right or wrong

answer in that case if like I said the

renal function continues to worsen the

next day I obtain another level before

uses before each dose just make sure the

patient only receives at those where the

trough is less than 20 patient case

Patient Case 5

number five this is a male who's eighty

two point one kilos 30

one-years-old we have the renal function

here seems okay they started this

patient on 1.25 grams every 12 hours for

skin infection they took the trough

right was taken before the fall for dose

and the level was five point for this

patient is young right kind of heavy the

trough is low so that those can be

increased to 1 point 5 gram every 12

hours I monitored the renal function

closely all right the patient's we know

function went up a little bit but went

back down but still just keep your eye

on it because the patient is on such a

high dose of the vancomycin now based on

the age the weight and the renal

function patient could have actually

even receive 1.5 grams every 12 hours as

the initial dose now this is a female

weighed 45 kilos 63 years old and here's

the renal function vancomycin one gram

every 12 hours we'll start on this

patient for skin infection once again

seems like what these patients have skin

infections right the dose is technically

okay for this patient based on the age

weight and renal function but the

patient's weight is on the lower end

right I would say in terms of weights

and the age is kind of on the high end

not 200 therefore you could have

technically and you could have been

conservative and started a patient on

you know just check the trough and go

based off that oh this is actually case

Patient Case 7

number seven so in this case we have a

male who is 98 kilos 49 years old and

here's the renal function also okay it

looks like it went down but then it went

back up right went up by 0.4 but then it

remained consistent for the next day and

this patient is getting vancomycin 1.25

grams every 12 hours to be infused over

one hour assuming you saw this order

before was verified

patient is heavy and not too older those

is okay but in this case the renal

function you just need some haunted

adrenal function right the dose is

definitely appropriate just make sure

the renal function that goes back down

this patient is really heavy and the

actually young you know so they could

they could probably take 1.25 grams with

no problem mainly because of the weight

and the patient is young on me yeah I

mean I know the renal function is at one

point three but it's 56 so there's a

chance of my improve right you give the

patient one dose let's say let's say the

patient only received one dose right

then when it got to fall for the renal

function got worse so the same cran was

like 1.6 right you could but you could

do in that case it seems like it's

getting worse right 0.9 1.3 1.6 is going

up you could check the level if you want

right or you could decrease this dose to

really an art there's no textbook way to

do this you know you gotta really use

your clinical judgment when you're

dosing these patients so just try to

think of the average patient as one gram

every 12 hours and then go on from there

to see if you should increase the dose

or decrease the dose and usually

sometimes you don't even know right with

the initial dose sometimes you may be

completely wrong

okay so just keep that in mind and try

to use your clinical judgment when it

comes to dosing vancomycin it should be

it should come naturally right because

it just makes sense

younger patient gets more have your

patients get more right all the patients

get less renal function code check level

right so you do everything based on the

trough really so don't be scared to ask

for a trough and always keep your eye on

the serum creatinine so that's the end

of this video I hope you guys enjoyed it

I hope I was able to you know explain

this in the best way to make

feel comfortable when it comes to

vancomycin and how we go about it in

clinical practice because in clinical

practice is definitely different from

what you learn in the textbook so notice

how I didn't calculate any doses for

these patients right I didn't use that

sense of 15 milligrams per kilogram I

just used my clinical judgment based on

the patient's age the patient's weight

to determine what those might be

appropriate so that's how you should

want to approach everything that you

learn in the textbook you want to bring

in so you know clinical practice and

just approach it in that direction so

this video is helpful make sure it's a

like comment subscribe and share it so

it's somebody that could definitely

benefit from it and I would definitely

appreciate that so and so then I hope

you take care and I'll see you soon