Vancomycin Therapeutic Drug Monitoring Quiz & Flashcards

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Questions and Answers

What are the two main uses of vancomycin?

Treat severe gram-positive infections due to organisms resistant to other antibiotics, such as methicillin-resistant staphylococci and ampicillin-resistant enterococci. 2) Treat infections caused by other sensitive gram-positive organisms in patients allergic to penicillins.

What is the mechanism of action of vancomycin?

Vancomycin is bactericidal and exhibits time-dependent or concentration-independent bacterial killing, meaning it kills bacteria most effectively when drug concentrations are 3-5 times the minimum inhibitory concentration (MIC) for the bacteria.

How is vancomycin administered and how are peak concentrations measured?

Vancomycin is administered as a short-term (1-1.5 hour) intravenous infusion. A peak vancomycin concentration is obtained after 1.5 hours, after allowing a 0.5-1 hour waiting period for distribution to finish before measuring the peak.

Why is a waiting period allowed before measuring peak vancomycin concentrations?

A 0.5-1 hour waiting period is allowed before measuring peak vancomycin concentrations because vancomycin exhibits a distribution phase, where the drug in the blood and tissues are not yet in equilibrium. Signup and view all the answers

What is the significance of vancomycin's time-dependent bacterial killing?

Vancomycin's time-dependent or concentration-independent bacterial killing means it is most effective at killing bacteria when its concentrations are 3-5 times the minimum inhibitory concentration (MIC) for the bacteria. Signup and view all the answers

What are the two main gram-positive organisms that vancomycin is used to treat?

Vancomycin is used to treat methicillin-resistant staphylococci and ampicillin-resistant enterococci. Signup and view all the answers

Why is vancomycin used to treat gram-positive infections in patients allergic to penicillins?

Vancomycin is used to treat gram-positive infections in patients allergic to penicillins because it is an alternative antibiotic option for these patients. Signup and view all the answers

What is the significance of vancomycin's bactericidal activity?

Vancomycin's bactericidal activity means it kills bacteria, rather than just inhibiting their growth. Signup and view all the answers

What is the recommended infusion time for vancomycin to avoid side effects like urticarial reactions, flushing, and hypotension?

2 hours or longer Signup and view all the answers

What is the primary route of elimination for vancomycin?

Vancomycin is almost completely eliminated unchanged in the urine primarily by glomerular filtration (≥90%). Signup and view all the answers

What is the therapeutic range for steady-state peak vancomycin concentrations?

20-40 μg/mL Signup and view all the answers

Why should clinicians consider measuring peak concentrations when large doses of vancomycin are given?

Clinicians should consider measuring peak concentrations when large doses are given (>1500 mg/dose) or for infections that require high peak concentrations (such as central nervous system infections) in order not to have a steady-state peak concentration that would be above the accepted toxic range (>80 μg/mL) in which could developed ototoxicity while receiving vancomycin. Signup and view all the answers

What vancomycin concentrations may be necessary for central nervous system infections?

40-60 μg/mL or direct administration into the cerebral spinal fluid Signup and view all the answers

What is the recommended trough and peak concentration range for vancomycin when high concentrations are needed for therapeutic reasons?

When high vancomycin concentrations are needed for therapeutic reasons, the recommended trough concentration is >15 μg/mL, and the recommended peak concentration is >40 μg/mL. Signup and view all the answers

What can happen if appropriate changes in vancomycin dosing are not made for ototoxicity?

Ototoxicity can become permanent Signup and view all the answers

Why is intramuscular administration of vancomycin usually avoided?

Intramuscular administration is usually avoided because this route has been reported to cause tissue necrosis at the site of injection. Signup and view all the answers

Which vancomycin concentrations are usually related to therapeutic outcome?

Trough concentrations (pre-dose or minimum concentrations) Signup and view all the answers

Why are trough concentrations important for vancomycin?

Because vancomycin follows time-dependent bacterial killing Signup and view all the answers

What are some of the allergic symptoms that vancomycin can cause?

Vancomycin can cause allergic symptoms such as chills, fever, skin rashes, and anaphylactoid reactions. Signup and view all the answers

What is the relationship between high trough concentrations of vancomycin and nephrotoxicity?

Since nephrotoxicity is related to high trough concentrations, measurement of this value should ensure therapeutic, non-nephrotoxic drug concentrations. Signup and view all the answers

What vancomycin concentrations relative to the organism's MIC are optimal for bactericidal effects?

3 to 5 times the organism's MIC Signup and view all the answers

What is the oral bioavailability of vancomycin?

Oral bioavailability is poor. Signup and view all the answers

What side effect is associated with vancomycin serum concentrations exceeding 80 μg/mL?

Ototoxicity Signup and view all the answers

Why is it important to assess renal function and auditory/vestibular function on a daily basis when high vancomycin concentrations are needed for therapeutic reasons?

When high vancomycin concentrations are needed for therapeutic reasons (trough >15 μg/mL, peak >40 μg/mL), assessment of renal function and auditory/vestibular function should be conducted on a daily basis. Signup and view all the answers

What are the typical minimum pre-dose or trough steady-state concentrations of vancomycin considered adequate to resolve infections with susceptible Staphylococcus aureus and Staphylococcus epidermidis organisms?

10-15 μg/mL Signup and view all the answers

Why has the therapeutic trough concentration range for vancomycin been expanded to 15-20 μg/mL in some institutions?

Due to the presence of MRSA with higher MIC values Signup and view all the answers

How does the penetration of vancomycin into lung tissue compare to its serum concentration?

Vancomycin penetrates into lung tissue poorly, with an average serum:tissue ratio of 6:1 Signup and view all the answers

What is the recommended steady-state trough concentration range for vancomycin in the treatment of hospital-acquired pneumonia, according to recent treatment guidelines?

15-20 μg/mL Signup and view all the answers

What potential adverse effect is associated with vancomycin trough steady-state concentrations above 15 μg/mL?

Increased incidence of nephrotoxicity Signup and view all the answers

Before attributing renal dysfunction to vancomycin-induced nephrotoxicity, what other potential causes should be ruled out in critically ill patients receiving vancomycin?

Hypotension or other nephrotoxic drug therapy (such as aminoglycosides, amphotericin B, or immunosuppressants) Signup and view all the answers

Compared to aminoglycoside antibiotics, how does the nephrotoxicity potential of vancomycin generally compare?

Vancomycin is usually considered to have less nephrotoxicity potential than aminoglycoside antibiotics Signup and view all the answers

Is vancomycin-related nephrotoxicity typically reversible or irreversible, and what factors influence the potential for residual damage?

Vancomycin-related nephrotoxicity is usually reversible with a low incidence of residual damage if the antibiotic is withdrawn or doses appropriately adjusted soon after renal function tests change Signup and view all the answers

What is the primary clinical indication that antibiotic therapy is effective?

A favorable response is indicated by decreasing white blood cell counts toward normal range, the fever curve approaching normal, and resolution of infection site tests/procedures. Signup and view all the answers

When should vancomycin steady-state serum concentrations be measured relative to the dosing schedule?

Vancomycin steady-state serum concentrations should be measured in 3-5 estimated half-lives, typically after the third dose which is 1-3 days after dosing commenced. Signup and view all the answers

What is the rationale for only measuring the trough vancomycin concentration?

Since vancomycin exhibits time-dependent bacterial killing, its efficacy is most closely related to the minimum serum concentration over the dosing interval. Signup and view all the answers

What clinical resources should be consulted when prescribing antibiotics?

Current microbiologic cultures, sensitivities, and antibiograms noting pathogen resistance patterns and minimum inhibitory concentrations should be consulted. Signup and view all the answers

What is the expected magnitude of transient serum creatinine increases due to vancomycin nephrotoxicity with adequate monitoring?

With adequate patient monitoring, transient serum creatinine increases of 0.5-2.0 mg/dL may occur as the only result of vancomycin nephrotoxicity. Signup and view all the answers

Describe the process of monitoring a patient's clinical response to antibiotic therapy over time.

The trend of the patient's white blood cell count, body temperature (fever curve), and infection site test results are monitored longitudinally to assess response to treatment. Signup and view all the answers

Why is it important to regularly consult antibiograms when prescribing antibiotics?

Antibiograms should be consulted regularly to note changes in resistance patterns and minimum inhibitory concentrations for pathogens over time. Signup and view all the answers

What pharmacokinetic principle governs the rationale for measuring trough rather than peak vancomycin levels?

Vancomycin exhibits time-dependent bacterial killing, where the minimum serum concentration over the dosing interval is most predictive of efficacy. Signup and view all the answers

Study Notes

Vancomycin Administration and Side Effects

Infusion rate-related side effects can occur when infusion times are shorter (~30 minutes or less), including urticarial or erythematous reactions, intense flushing, tachycardia, and hypotension.
These side effects can be largely avoided with longer infusion times.

Ototoxicity and Serum Concentrations

Ototoxicity has been reported when vancomycin serum concentrations exceed 80 μg/mL.
The therapeutic range for steady-state peak concentrations is usually considered to be 20–40 μg/mL.
Steady-state peak concentrations of 40–60 μg/mL or direct administration into the cerebral spinal fluid may be necessary for certain infections.
Ototoxicity can be permanent if appropriate changes in vancomycin dosing are not made.

Therapeutic and Toxic Concentrations

Vancomycin is administered as a short-term (1-1.5 hour) intravenous infusion, with a distribution phase that requires a 1/2–1 hour waiting period before measuring peak concentrations.
Peak vancomycin concentrations are obtained after 1.5 hours.
Minimum pre-dose or trough steady-state concentrations of 10–15 μg/mL are usually adequate to resolve infections with susceptible organisms.
Higher trough concentrations (15–20 μg/mL) may be necessary in institutions with antibiograms that include MRSA with higher MIC values.

Nephrotoxicity and Clinical Monitoring

Trough vancomycin steady-state concentrations above 15 μg/mL are related to an increased incidence of nephrotoxicity.
Vancomycin-related nephrotoxicity is usually reversible with a low incidence of residual damage if the antibiotic is withdrawn or doses are appropriately adjusted soon after renal function tests change.
Clinical monitoring parameters include antibiotic therapy prescription based on current microbiologic cultures and sensitivities, antibiograms, and patient response to treatment.
Vancomycin steady-state serum concentrations should be measured in 3–5 estimated half-lives, and favorable response to antibiotic treatment is usually indicated by decreasing white blood cell counts, normalized body temperature, and resolution of infection site tests or procedures.

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Description

This quiz covers the fifth lecture of the Department of Clinical Pharmacy course, focusing on Vancomycin. Vancomycin is a glycopeptide antibiotic used to treat severe gram-positive infections, especially those resistant to other antibiotics like methicillin and ampicillin.

Therapeutic Drug Monitoring Lecture 5: Vancomycin

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