Vanco Practice

HM is a 78 year old male receiving vancomycin for pneumonia. He has been getting 1000mg IV q12h for several days. His vancomycin trough at steady state is 13.4 mg/L. The team would like AP's vancomycin trough to be as close to 20 mg/L as possible. His renal function is stable. Which of the following would be the most appropriate new regimen to recommend for AP? 

A. 1500 mg IV q12h 

B. 1250 mg IV q12h 

C. 1750 mg IV q12h 

D. 750 mg IV q8h 

A

In which of the following situations would it be most appropriate to administer a vancomycin loading dose? 

A. In a patient with pneumonia and acute kidney injury 

B. In a patient with an uncomplicated UTI 

C. In a patient receiving prophylactic vancomycin for a surgery 

D. In a patient with cellulitis and CrCl of 70ml/min 

A

Loading doses of vancomycin (and other drugs) shorten time to achievement of steady state and reduce time to effect, so they are most appropriate for patients with severe infections and longer elimination half-lives as would occur in AKI. 

Which of the following organisms and sites would require the most aggressive dosing of vancomycin or consideration of an alterative antibiotic? 

A. Staph aureus, MIC of 2, pneumonia 

B. Coagulase negative Staph, MIC of 2, skin infection 

C. Staph aureus, MIC of 2, urinary tract infection 

D. Coagulase negative Staph, MIC of 2, bacteremia 

A

Organisms with higher MICS to vancomycin and more difficult-to-penetrate infections (pneumonia, osteomylitis, CNS infections) are generally more difficult to treat. Coagulase negative Staph is not as virulent as Staph aureus so does not require as aggressive of dosing. 

Which of the following best describes why it is important to consider the minimum inhibitory concentration (MIC) of an organism that is being treated with vancomyin? 

A. As MIC goes up, we need to adjust dosing to target higher vancomycin peaks 

B. As MIC goes up, it becomes harder to achieve an adequate amount of time above the MIC of the organism 

C. A higher MIC means there is a greater risk of adverse effects from vancomycin if the dose is held constant 

D. As MIC goes up, vancomycin becomes more effective 

B

Vancomycin is a time-dependent antibiotic and optimal bacterial killing is acheived when AUC/MIC exceeds 400, so as MIC goes up, it becomes necessary to give more frequent doses and it may become difficult to give enough vanco to achieve an AUC/MIC of 400.

MIC does not relate to side effects.

Vanco peaks do not correlate with effectiveness.

Vanco becomes less effective as MIC increases.

Please select the true statement regarding Vancomycin pharmacokinetics. 

A. Vancomycin distributes extensively into the meninges 

B. Vancomycin undergoes significant hepatic metabolism 

C. High peaks are a risk factor for vancomycin-induced nephrotoxicity 

D. Vancomycin has poor penetration into the lung 

D

Vancomycin does not penetrate into bone, CNS, or the lung well. It achieves approximatly 20% penetration into the lungs fluid. It is not hepatically metabolized to a significant extent, but is renally eliminated largely unchanged. Nephrotoxicity is less common than the past because the formulation today is more pure than formulations have been historically. 

Which of the following organisms and sites would be most difficult to treat with
vancomycin? Briefly explain the rationale for your answer.

A) Staph aureus MIC of 1, CNS infection
B) Staph aureus MIC of 0.5, blood stream infection
C) Staph aureus MIC of 0.5, pneumonia
D) Staph aureus MIC of 1, soft tissue infection

A

Infections caused by organisms with higher MICs and difficult-to-penetrate infections
(such as pneumonias, CNS infections, osteomyelitis, and endocarditis) are more difficult to treat because vancomycin concentrations need to remain higher longer and
vancomycin does not penetrate to the site of infection well.

List 3 potential adverse effects from vancomycin, risk factors for the adverse effects,
and management as appropriate.

a) Infusion-related reaction (red man syndrome)

• risk factors: high doses and fast infusion rate

• management: slow rate of infusion, consider diphenhydramine if
  reaction persists with slower infusion.

b) Nephrotoxicity

• risk factors: high troughs, prolonged therapy, concomitant
  nephrotoxins (e.g., aminoglycosides), other kidney insults (e.g., hypotension,
  shock)

• management: avoid supratherapeutic troughs and concomitant
  nephrotoxins

c) Ototoxicity

• risk factors: excessively high peaks, concomitant ototoxic agents
  (e.g., aminoglycosides)

• management: consider audiology monitoring when
  receiving concomitant ototoxic agents