Vancomycin Trough Adjustment

[nampa]

There seems to be contention among pharmacists about the most propitious scheme of adjusting vanc troughs.
For instance, if a trough (goal 15-20) comes back above 20, at what level would one hold the dose, at what level would one adjust the dose, at what level would one extend the interval? How would a goal of 10-15 make these answers different?

My understanding was that dose changes, for instance with a goal of 15-20, should be done for levels 20-23, for levels higher than 23, the dose should be held and once the random level falls beneath 20, the dosing interval should be extended to the next level, e.g. q12-q24hr, unless it is already at q24hr, at which time a dose adjustment should be made.

How does this reconcile with the dose affecting peak and the interval affecting trough? I don't feel comfortable increasing intervals for small over trough levels of a few mcg/ml levels.

Thanks

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[owlegrad]

If your facility has a protocol, follow it. Going outside the protocol will only put a target on your back anytime your adjustment doesn't work out 100% (and possibly even when it does).

If no protocol...ask the director if you can write one? There is really no good reason you should have to reinvent the wheel every time you need to dose something as common/simple as vancomycin.

As for your examples, I think your numbers are pretty good. For something 20-23 it is reasonable to just adjust the dose and recheck. For >23 holding the dose before resuming seems prudent. When the goal is 10-15 I personally would change the dose for anything 16-23 then hold for anything >23. I also would want to see the history of the patient - is this the first trough? If it is the first trough I will hav a lower threshold for holding a dose since they might still be on the rise. The 10th trough? Have they been stable or erratic? Someone who was stable that has one high peak I am more likely not to hold a dose vs someone who has been a rollercoaster.

As for when to lower the dose vs extend the interval I would respectfully ask you to review the basics of kinetics. Or use a resource such as GlobalRPh. You lower the dose when it makes sense to do so and you extend the interval when that makes more sense. Extending the interval will always have the larger effect on the trough while lowering the dose will always have the larger effect on peak (principles of kinetics). So for someone really close to goal it probably makes more sense to adjust the dose. For someone who is way outside the goal a change of interval will almost certainly be needed.

Hope this helps!

 

[mentos]

Yeah every hospital or LTC should have a protocol. Shouldn't even have to think about what to do for adjustments.

 

[PharmDBro2017]

Yeah every hospital or LTC should have a protocol. Shouldn't even have to think about what to do for adjustments.

Sure, but every case should be individualized. Treat the patient, not the number. Age, SCr baseline, AKI, indication and other patient-specific factors, etc. and how froggy/conservative you feel like dosing, it changes from case to case with how I dose it. I also take into account the reliability of the lab, which differs at every facility. (Do they miss troughs? Do they draw them incorrectly after the bag is hung? Does it take 3 hours to get a trough back or 30 minutes?) There are a lot of things to be considered when dosing.

Do you guys actually just follow protocol each and every time?

 

[owlegrad]

Sure, but every case should be individualized. Treat the patient, not the number. Age, SCr baseline, AKI, indication and other patient-specific factors, etc. and how froggy/conservative you feel like dosing, it changes from case to case with how I dose it. I also take into account the reliability of the lab, which differs at every facility. (Do they miss troughs? Do they draw them incorrectly after the bag is hung? Does it take 3 hours to get a trough back or 30 minutes?) There are a lot of things to be considered when dosing.

Do you guys actually just follow protocol each and every time?

Easily one of my biggest pet peeves when trying to dose vancomycin. If you can't trust the value, what's the point of even monitoring in the first place? I hate trying to track down when a bag was hung vs when a trough was drawn.

As for following protocol, have you ever tried? I don't mean that snarky, it's just when you get used to using a protocol you realize what a time saver it really is. Also following a protocol doesn't mean ignoring age, SCr, etc. I just means using a standardized approach for dealing with them. It's very convenient. You just have to remember not to turn off your brain when using it.

 

[PharmDBro2017]

Easily one of my biggest pet peeves when trying to dose vancomycin. If you can't trust the value, what's the point of even monitoring in the first place? I hate trying to track down when a bag was hung vs when a trough was drawn.

As for following protocol, have you ever tried? I don't mean that snarky, it's just when you get used to using a protocol you realize what a time saver it really is. Also following a protocol doesn't mean ignoring age, SCr, etc. I just means using a standardized approach for dealing with them. It's very convenient. You just have to remember not to turn off your brain when using it.

I tried it when I first graduated but didn't like the one size fits all approach. I've had better outcomes doing things myself (thus far). I'm the person most people wish would follow protocol

 

[Rockinacoustic]

My step-wise approach to Vanco is such:

1. Review patient profile to collect reasons to d/c Vanco
2. Explain said reasons to physician and get a d/c order
3. ...
4. Do more important pharmacist things

Annnd if the above fails then I will use our protocol, or if i deviate from protocol I document why.

 

[owlegrad]

I tried it when I first graduated but didn't like the one size fits all approach. I've had better outcomes doing things myself (thus far). I'm the person most people wish would follow protocol

I used to feel that way to be honest. And in my heart of hearts I still think I know better than the protocol. But after a time my coworkers wore me down to just using it so I don't have to hear the nagging little comments about it and now I actually like just following it. lol Of course there are plenty of times it makes sense not to follow it exactly but it is good enough for most cases.

The funny part to me is our newest pharmacist doesn't use it and anytime his dosing doesn't work out I think to myself "should have followed the protocol". LMAO

But he and I actually share the same "problem" - we would both dose much more aggressively than our coworkers who act like 12 is "pretty much" 15 and that going over 20 immediately does irreparable harm.

 

[Monsterdaddy]

ASHP is planning on tossing out the whole screwed up scheme of dosing by trough in favor of AUC although they are screwing it up again by promoting Bayesian software.

 

[PharmDBro2017]

ASHP is planning on tossing out the whole screwed up scheme of dosing by trough in favor of AUC although they are screwing it up again by promoting Bayesian software.

What's the reasoning behind this?

 

[lane one]

I don't mean to oversimplify it, but adjusting doses is usually common sense. That being said, I still use a kinetics calculator because I like to justify my dosing with patient specific half-life data. Most dose adjustments fall into the following scenarios:

1. Trough is slightly high, creatinine is unchanged. Interpretation: Interval is probably OK, just need to back off the dose a little
2. Trough is hella high, creatinine is either unchanged or its bumped. Interpretation: Regardless of whether there's been a change in clearance, your interval is probably too short resulting in accumulation. Perform calculations to determine the best dose/interval going forward.
3. Trough is low. Interpretation: Dose is too low, frequency too long or both. Use kinetics calculator to pin down a new dosing strategy based on the data you now have.

If you're a fancy rounding RPh, substituted the creatinine data for UOP for even better results. Also, if your trough is >20, you should probably be holding that dose. There's really no reason not to hold it, re-work your dosing, re-start it at a time where your theoretical is <20 again.

 

[farmadiazepine]

Vancomycin Pharmacokinetics Calculator

www.anirdesh.com

This calculator is a game changer for vancomycin dosing. It is so point on. After one of my colleagues showed me this, I haven't ever had a problem with vancomycin dosing and troughs

 

[El Trombopag]

What's the reasoning behind this?

https://www.ashp.org/-/media/assets/policy-guidelines/docs/draft-guidelines/draft-guidelines-ASHP-IDSA-PIDS-SIDP-therapeutic-vancomycin.ashx?la=en&hash=8126CEE49F401CDEE5DB49712225F0A4518DB94B

There are a couple major institutions, teaching hospitals in our area that are already establishing trough goals of 10-20 mcg/mL for everything.

Somewhat, but not entirely based on the working ASHP draft I’m told

 

[nampa]

My place it almost is always interval changing. I was taught if <23, lower dose. How does scr rising or volatility in scr change this?
It seems that they always extend the interval or hold. The only time they lower dose is if the interval gets beyond q24hrs, and they adjust the dose just so the next trough isn't too far away.
Could we get some elaboration, in depth, of what the rph's on this forum do for van dosing. thank you.

 

[Sparda29]

I was taught to be aggressive with Vancomycin. Going above 20 trough isn't gonna harm anyone.

 

[ldiot]

You have to look at all factors. You aren't going to hold a dose if a patient has a trough of 22 with osteo, but if some lady has MRSA cellulitis in her fat creases with a trough of 26 then yeah hold the dose.

Also it is important to see if the trough was drawn correctly because a lot of nurses are *****s and draw the trough with morning labs or will hang the next bag then draw the trough 20 minutes after.

And you don't always increase interval before lowering dose. If someone is on vanco 2g q12h there no reason to go to q24h dosing the the trough is high when you could just reduce the dose...

 

[nampa]

I understand that part but can someone elaborate on the interval vs. dose change in context of age and scr variations

 

[nampa]

I don't mean to oversimplify it, but adjusting doses is usually common sense. That being said, I still use a kinetics calculator because I like to justify my dosing with patient specific half-life data. Most dose adjustments fall into the following scenarios:

1. Trough is slightly high, creatinine is unchanged. Interpretation: Interval is probably OK, just need to back off the dose a little
2. Trough is hella high, creatinine is either unchanged or its bumped. Interpretation: Regardless of whether there's been a change in clearance, your interval is probably too short resulting in accumulation. Perform calculations to determine the best dose/interval going forward.
3. Trough is low. Interpretation: Dose is too low, frequency too long or both. Use kinetics calculator to pin down a new dosing strategy based on the data you now have.

If you're a fancy rounding RPh, substituted the creatinine data for UOP for even better results. Also, if your trough is >20, you should probably be holding that dose. There's really no reason not to hold it, re-work your dosing, re-start it at a time where your theoretical is <20 again.

I agree with this, particularly point one; however, someone was frowned upon for not doing this. It was the first trough, so it would be expected to increase a little (before fifth dose is more steady state), but even second or third troughs the facility seems to push for interval changes...

 

[Rockinacoustic]

You are not going to get a straight answer because therapeutic management depends on so many factors outside of the PK silo we were taught in school. Is the patient's BUN/SCr and UOP stable? Are they on concomitant nephrotoxins? Is the Vancomycin MIC = 1? Are we treated E. faecium or faecalis? Is the patient clinically improving despite a less than goal trough level, etc.

I really encourage you to read the ASHP Vancomycin guidelines, which will very soon be updated.

Also whoever is frowning upon you should explain their practice style. I've developed my clinical acumen from so many preceptors/colleagues in addition to my institution protocol.

 

[nampa]

You are not going to get a straight answer because therapeutic management depends on so many factors outside of the PK silo we were taught in school. Is the patient's BUN/SCr and UOP stable? Are they on concomitant nephrotoxins? Is the Vancomycin MIC = 1? Are we treated E. faecium or faecalis? Is the patient clinically improving despite a less than goal trough level, etc.

I really encourage you to read the ASHP Vancomycin guidelines, which will very soon be updated.

Also whoever is frowning upon you should explain their practice style. I've developed my clinical acumen from so many preceptors/colleagues in addition to my institution protocol.

Thank you for the reply. MIC for Vanc is under 2, which is valid for all treatments, or is it institution specific? Can you elaborate on the BUN/Scr and UOP? If I see the Scr (why isn't crcl considered more important for this issue?) increase, I'll lower dose, perhaps before the VTR; however, I'm not sure what range as a proportion of the original, or even total scr, I should base that decision on.
Still, my place is very interval oriented. They expressly say the dose adjustment is almost never done. When do you guys like to adjust dose vs. interval, with and without the factors addressed above?

 

[owlegrad]

What is the rational for only changing interval? That makes no sense. If the trough is 21 and the dosing is q12 going to q24 will push the trough well below target. In that case your only option is a slight dose reduction, unless you want to do an obnoxious q18 schedule (please don't do this).

I personally will not change a dose based on a change in SCr. It's not evidence based (that I know of, I hope if I am wrong someone will correct me) and highly variable/unpredictable. I might order a tough to be done sooner than usual but even then it would have to be a pretty dramatic change to warrant that in my mind. In three years I have probably done that perhaps half a dozen times, max.

You are right that SCr is more important than BUN for dosing. Actually while we are on the topic can anyone explain to me why we monitor BUN for vancomycin therapy? AFAIK we don't use it for dosing so what's the point?

What is the context for this frowning? Are they trying to help you follow an institutional process or is it someone who just thinks they know better than you? We can give you the best answers in the world but if what you care about is this person's approval I don't see how anything we tell you will help your situation. Are you going to correct this person if they tell you something different than we do?

 

[Rockinacoustic]

@nampa Cockroft-Gault is an estimate in healthy subjects with stable renal function. A 65 year old with stable SCr and an CrCl of 60 is clearing drug faster than a 30 year old with a SCr bump from 0.7 to 2.0 and an CrCl of 60.

@owlegrad You absolutely alter the dosing for an abrupt change in SCr. If my patient's SCr rises substantially in 24 hours I am going to look at urine output, concomitant nephrotoxins, and potentially stop scheduling doses until i have a random level within goal if they are in AKI.

 

[owlegrad]

@owlegrad You absolutely alter the dosing for an abrupt change in SCr. If my patient's SCr rises substantially in 24 hours I am going to look at urine output, concomitant nephrotoxins, and potentially stop scheduling doses until i have a random level within goal if they are in AKI.

How much do you change it? When do you order the next trough? Why not just order a trough before the next dose and go from there?