couple possible reasons, if it is MRSA and susceptible to vancomycin, zyvox comes in tablets while vanco is IV only - don't have to set patient up on outpatient IV/home health.
complicated skin and soft tissue infections or diabetic foot - zyvox has better tissue penetration.
"allergy" to vanco?
strep pneumo increasing drug resistance.
at our hospital, it is restricted to Infectious Disease docs only.
Yes Zyvox (i.e. linezolid) should be restricted. Overuse of antibiotics is unfortunately a problem w/ all antibiotics which is why antimicrobial resistance is so much of a concern. However, w/ a drug like zyvox if resistance develops to it then you are really running short on alternatives. Therefore Zyvox should typically be reserved for the following:
-hospital acquired MRSA pts that are allergic and/or can't tolerate vanco (assuming of course micro culture/sensitivity show resistance to synercid/bactrim/clindamycin)...Note: community acquired MRSA is often susceptible to bactrim or clindamycin.
-or Vancomycin resistant enterococcus (VRE) urinary/bacteremia infections
-or any other gram positive infection resistant all other abx including vanco
Interaction b/w zyvox and fentanyl, well it is potential two fold...
The first easier of the two to explain is the historial interaction of monoamine oxidase inhibitors (i.e. MAOIs, outside of zyvox's antimicrobial activity it is a weak MAOI) to potentially cause respiratory depression which can be compounded when used w/ opiates. The problem w/ this interaction is that it is largely based on very old literature w/ various other case reports citing how the combo can be used safely. So basically it may be ok (except w/ demerol), but increased monitoring is warranted given potential for adverse outcomes.
Other interaction would be potential for serotonin syndrome (SS) as expressed by All4MyDaughter mentioned previously.
Several opioids may also have weak neurotransmitter activity thereby potentially increasing serotonin (5HT)/ norepinephrine (NE) at the synapse thus possibly increasing risk for SS. Most notable opiates (or opaite like drugs) which may cause this are: fentanyl, ultram, meperidine (really shouldn't be used that often anyways), darvocet, and methadone (hope I am not forgetting anything).
The same incr risk for causing SS when using zyvox w/ other agents would be w/ any of the following: antidepressants (SSRIs, TCAs, MAOIs, etc), migraine meds(triptans, have 5HT activity), antipsychotics
(often block 5HT-2A/C and/or may augment 5HT-1A), and various other 5HT acting meds.
Generally the interaction w/ zyvox and other MAOIs is an absolute contraindication and the others are often relative w/ avoidance the preferred choice.
In the "real world" if you have a pt that requires zyvox for an infection and they may already be on a potential interacting drug, it would be in the best interest to stop the other offending drug (assuming not necessary for life sustainment) and start the zyvox as if appropriately indicated, the infection is quite severe. Waiting 14 days after the antidepressant is d/c'd to start zyvox isn't always possible given severity of infection.
If combos of zyvox and other 5HT/NE types of drug have to be used for whatever reason then monitoring for sign/symptoms of SS (incr. temp, change in mental status, tachycardia, incr BP, hyperreflexia) is the best you can do.
SS isn't really that common. I think a review in Mayo Clinic or Clinical Infectious Diseases found a prevalence of <10% (might of been even lower <1-5%??), but if it occurs then the complications are potentially fatal. One of the main things to consider in drug therapy is how many drugs are on board that are actually affecting the neurotransmitter.
Try to keep it to just two if possible assuming zyvox alone isn't possible. For instance most of the case reports of SS cite pts who were on one antideppressants previously to starting zyvox for an infection and were fine until some ultram (or other opiate) or maybe some trazodone or TCA was added for underlying neuropathic pain or sleep (in the case w/ trazodone). So the more drugs on board that affect 5HT neurotransmission the more likely SS is to occur.
Please see the following for the FDA warning:
http://www.fda.gov/cder/warn/2005/Zyvox_wl.pdf (see p4)
http://www.fda.gov/cder/drug/advisory/SSRI_SS200607.htm
Sorry for being so length on this one.
