Questions about PCN allergy

[platon20]

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Assuming its a true allergy, what classes of abx are off limits?

My list:

1) ANY generation of cephalosporins
2) ANY carbapenems

What about the following?

Vanc?
Fluoroquinolones?
Zosyn?
TMP/SMX?

 

[Priapism321]

Assuming its a true allergy, what classes of abx are off limits?

My list:

1) ANY generation of cephalosporins
2) ANY carbapenems

What about the following?

Vanc?
Fluoroquinolones?
Zosyn?
TMP/SMX?

Since piperacillin/tazobactam contains a penicillin, you may want to stay away from that one. I would still consider giving a carbapenem if it were clinically warranted. And, if there were no way around using a penicillin/cephalosporin, desensitization protocols offer a viable scenario where nothing may be completely off limits.

 

[WVUPharm2007]

Assuming its a true allergy, what classes of abx are off limits?

My list:

1) ANY generation of cephalosporins
2) ANY carbapenems

What about the following?

Vanc?
Fluoroquinolones?
Zosyn?
TMP/SMX?

The cephalosporins have a cross sensitivity rate of under 5% (if not lower). It depends on how conservative you want to be.

So...

Ceph - Many "double check" with the physician to CYA. If an alternative is available, they usually go with it to be safe.
penems - meh, not really. They are beta lactams like penicillin, but I don't believe the cross sensitivity chances are too big of a deal
Zosyn - another beta lactam...same deal as above with the cephalosporins
Vanc - no
quinolones - no
tmp/smx - no

 

[Priapism321]

Ceph - Many "double check" with the physician to CYA. If an alternative is available, they usually go with it to be safe.
penems - meh, not really. They are beta lactams like penicillin, but I don't believe the cross sensitivity chances are too big of a deal
Zosyn - another beta lactam...same deal as above with the cephalosporins
Vanc - no
quinolones - no
tmp/smx - no

I worry about this call, it is not just a beta-lactam, it is in the drug class known as the "penicillins."

 

[njac]

Also, the higher you go in cephalosporin generation the less pcn cross sensitivity. So Cefazolin would be more likely to cause a reaction than Ceftriaxone or Cefepime.

For the first dose I often advise the nurse to keep an eye on the patient and if they're that worried they can premedicate with benadryl.

 

[ItsOverZyvox]

The cephalosporins have a cross sensitivity rate of under 5% (if not lower). It depends on how conservative you want to be.

So...

Ceph - Many "double check" with the physician to CYA. If an alternative is available, they usually go with it to be safe.
penems - meh, not really. They are beta lactams like penicillin, but I don't believe the cross sensitivity chances are too big of a deal
Zosyn - another beta lactam...same deal as above with the cephalosporins
Vanc - no
quinolones - no
tmp/smx - no

Be careful there dood.

 

[ItsOverZyvox]

so abx topic...we get 4 posters. NJ, Mikey, Priap, and me..

 

[WVUPharm2007]

I worry about this call, it is not just a beta-lactam, it is in the drug class known as the "penicillins."

The difference is the complexity of the side chain. Piperacillin's side chain is much more complex than that of amp, amoxil, and pen g. One could certainly argue that it is less likely with zosyn. Compare the structures of the first gen cephs to amoxil to piperacillin to penacillin. Which do you think is the least similar structurally? The big thing appears to be more about the side chains than the lactam chemical structure. The more complex the side chain, the lesser of a chance for cross sensitivity.

But, really, it's all a guess. Maybe the allergic reaction DOES stem from the lactam structure....it depends on the patient.

For legal reasons call the doc...period. I always do. All the way up to 4th gen cephs...

 

[WVUPharm2007]

Here's a nice little article I found...

 

[KARM12]

Would still consider ceph, carbepenems..would stay away from zosyn.

Thanks. Now back to no life...i.e. residency

 

[ItsOverZyvox]

What is the difference is the complexity of the side chain? Piperacillin's side chain is much more complex than that of amp, amoxil, and pen g. One could certainly argue that it is less likely with zosyn. Compare the structures of the first gen cephs to amoxil to piperacillin to penacillin. Which do you think is the least similar structurally? The big thing appears to be more about the side chains than the lactam chemical structure. The more complex the side chain, the lesser of a chance for cross sensitivity.

But, really, it's all a guess. Maybe the allergic reaction DOES stem from the lactam structure....it depends on the patient.

For legal reasons call the doc...period. I always do. All the way up to 4th gen cephs...

I'm not looking at the structures now...but we have always considered piperacillin, carbenicillin, and ticarcillin as extended spectrum penicllins..and not cephalosporins.

So with 5 to 15% cross sensitivity allowed for safety of cephalosporins from PCN allergy, we never challenge th PCN allergy with Pip, car, and tic.

 

[ItsOverZyvox]

BTW, I bet we're doing the homework for the OP.

 

[WVUPharm2007]

Pharmacology doesn't equal structure....and stereochemical structure is what determines cross sensitivity....but I digress...call and put the legal liability on the prescriber. It's the best part about being a pharmacist. Dump it all off on the physicians. Then if the patient is the 0.01% that has an anaphylactic reaction, it ain't on you.

 

[WVUPharm2007]

BTW, I bet we're doing the homework for the OP.

Oh, definately.

Nobody talks about Bactrim with the generic abbreviations without knowning what class it is in...fo shizzle.

 

[Priapism321]

Pharmacology doesn't equal structure....and stereochemical structure is what determines cross sensitivity....but I digress...call and put the legal liability on the prescriber. It's the best part about being a pharmacist. Dump it all off on the physicians. Then if the patient is the 0.01% that has an anaphylactic reaction, it ain't on you.

Unfortunately, that isn't necessarily how the story goes in my world. In my world, it is a physician paging/calling me, saying "What the hell do I do, I have the pen in hand (or, in my current institution, all clinical pharmacists have relatively unrestricted order writing authority, so we often will be writing the order for whatever strategy is ultimately devised), patient has a severe allergy to penicillin (patient states it put them in the ICU), tell me what we are going to do for them? Temp. is 40, BP is 94/57, creatinine doubled over night, cultures are turning up positive." So, who am I supposed to call? And, I take personal and professional responsibility when I get involved in making these types of "suggestions" to prescribers. However, I understand that responsibility does not equal legal liability.

 

[ItsOverZyvox]

Unfortunately, that isn't necessarily how the story goes in my world. In my world, it is a physician paging/calling me, saying "What the hell do I do, I have the pen in hand (or, in my current institution, all clinical pharmacists have relatively unrestricted order writing authority, so we often will be writing the order for whatever strategy is ultimately devised), patient has a severe allergy to penicillin (patient states it put them in the ICU), tell me what we are going to do for them? Temp. is 40, BP is 94/57, creatinine doubled over night, cultures are turning up positive." So, who am I supposed to call? And, I take personal and professional responsibility when I get involved in making these types of "suggestions" to prescribers. However, I understand that responsibility does not equal legal liability.

Break out the Sepsis protocol and get APACHE score calculated!

 

[ItsOverZyvox]

Meanwhile in WV...

Mike's DOP: Oh Mike... can you type out a Sepsis protocol? Did you learn that in school?

Mike: uhhh...ok, Yes Ma'am...

 

[WVUPharm2007]

Meanwhile in WV...

Mike's DOP: Oh Mike... can you type out a Sepsis protocol? Did you learn that in school?

Mike: uhhh...ok, Yes Ma'am...

Play dumb.

A: Sepsis? I thought we got city water and sewage here! We have a sepsis system? Wow. This really IS country!!

 

[WVUPharm2007]

Unfortunately, that isn't necessarily how the story goes in my world. In my world, it is a physician paging/calling me, saying "What the hell do I do, I have the pen in hand (or, in my current institution, all clinical pharmacists have relatively unrestricted order writing authority, so we often will be writing the order for whatever strategy is ultimately devised), patient has a severe allergy to penicillin (patient states it put them in the ICU), tell me what we are going to do for them? Temp. is 40, BP is 94/57, creatinine doubled over night, cultures are turning up positive." So, who am I supposed to call? And, I take personal and professional responsibility when I get involved in making these types of "suggestions" to prescribers. However, I understand that responsibility does not equal legal liability.

Well, sure, if they ask something and therapy is needed, that's different. But if it's some stupid post-op abx therapy were they want iv ancef off of some protocol form...it's legal responsibility dumping time. And it thus gets dumped off to he guy that gets paid more (before accounting for insurance for said liability.)

 

[Priapism321]

Well, sure, if they ask something and therapy is needed, that's different. But if it's some stupid post-op abx therapy were they want iv ancef off of some protocol form...it's legal responsibility dumping time. And it thus gets dumped off to he guy that gets paid more (before accounting for insurance for said liability.)

Haha, works for me. Anyhow, going to Vegas this weekend, where is there money to be made on the college football schedule? Washington State +42.5?

 

[njac]

Pharmacology doesn't equal structure....and stereochemical structure is what determines cross sensitivity....but I digress...call and put the legal liability on the prescriber. It's the best part about being a pharmacist. Dump it all off on the physicians. Then if the patient is the 0.01% that has an anaphylactic reaction, it ain't on you.

you are correct.

If I remember right the side chains determine the reactivity - stuff on the 7 spot has a higher incidence of allergic reaction. That remains true even within the cephalosporin class.

Although Azactam and Ceftazidime have a side chain in common so are often cross-reactive.

(back to writing an Abx for Dummies lecture for the physicians at this place)

 

[WVUPharm2007]

They are giving Syracuse 24 points on USF. They lost to Pitt by a TD and WVU by 11. Pitt beat USF just a few weeks back, too. They can scrap.

The idea of betting money on any BE team is frightening though. Each and every one of them are inconsistent as hell.

 

[SpirivaSunrise]

you are correct.

If I remember right the side chains determine the reactivity - stuff on the 7 spot has a higher incidence of allergic reaction. That remains true even within the cephalosporin class.

Although Azactam and Ceftazidime have a side chain in common so are often cross-reactive.

Yep (it's probably not just the beta-lactam structure)...Cefurox, Cefpodox, Cefdinir and Ceftriax are generally a safe bet that I used to recommend because of the different side chain.

To the OP...have you checked out any desensitization protocols that Pri also mentioned (either oral or IV)? It's a good topic to bring to the discussion you're having...in whatever setting it's in.