OXAZOLIDINONES

Question 1

What drug is termed an OXAZOLIDINONE?

Answer 1

Linezolid (Zyvox)
approved in the United States in 2000, is the first drug in a new class of antibiotics,
a unique class of synthetic antibiotics.

Question 2

MOA of Linezolid (Zyvox)

Answer 2

inhibitors of bacterial ribosomal protein synthesis, but unlike other antibiotics, they stop the first step in synthesis in which bacteria assemble ribosomes from their dissociated subunits.
(Linezolid does this by binding to the 50S ribosomal subunit, thus preventing the formation of a 70S initiation complex required for protein synthesis. No other known antibiotic uses this process.)

Question 3

What is Linezolid (Zyvox) active against?

Answer 3

most effective against aerobic gram-positive bacteria.
group A and B Streptococcus, S. aureus (both MSSA and MRSA.
retains activity against the most resistant forms of Enterococcus including VRE

Question 4

What is the resistance activity against Linezolid (Zyvox)

Answer 4

resistance is not widespread and considered uncommon

Question 5

What is the absorption of Linezolid (Zyvox)

Answer 5

Linezolid is rapidly and completely absorbed after oral administration

Question 6

What is the distribution of Linezolid (Zyvox)

Answer 6

only 31% protein bound and the binding is dependent on concentration. High drug concentrations are found in the skin and other well-perfused tissues. Peripheral tissue concentrations far exceed plasma concentrations

Question 7

How do Linezolid (zyvox) concentrations compare between maternal plasma and placenta?

Answer 7

Breast milk concentrations are similar to those in the maternal plasma

Question 8

What is the metabolism of Linezolid (Zyvox)

Answer 8

two inactive metabolites of linezolid created by oxidation of the morpholine ring. Because this is a nonenzymatic oxidation, this drug does not induce the CYP system

Question 9

What is the excretion of Linezolid (Zyvox)? Is renal or hepatic dosing needed?

Answer 9

Nonrenal excretion accounts for 65% of the total clearance; of the remainder, 30% is excreted unchanged in urine. No dosage adjustments are required for impaired hepatic or renal function

Question 10

When is Linezolid (Zyvox) contraindicated?

Answer 10

Concomitant use or use within 2 weeks of a monoamine oxidase inhibitor (MAOI) with linezolid is contraindicated.
Serotonin syndrome or hypertension

Question 11

What are the recommendations for children using Linezolid (Zyvox)?

Answer 11

Linezolid is approved for use in children from birth. Preterm infants and neonates require reduced dosing because of slower clearance.

Question 12

What is a unique precaution clinicians need to be aware of before prescribing Linezolid (Zyvox) ?

Answer 12

Bone marrow activity suppression AKA Myelosuppression (anemia, leukopenia, pancytopenia, and thrombocytopenia) has been reported in patients receiving linezolid

Question 13

What kind of food must be avoided when receiving Linezolid (Zyvox)?

Answer 13

Because significantly elevated blood pressure may occur if taken with tyramine-rich foods, the amount of tyramine consumed at any one meal should be limited (less than 100 mg/meal).

Question 14

The most common adverse effect of Linezolid (Zyvox)?

Answer 14

most common adverse reactions reported were diarrhea, headache, and nausea.
C diff.

Question 15

What drug interactions does Linezolid (Zyvox) have?

Answer 15

Because linezolid is a reversible, nonselective inhibitor of monoamine oxidase, it also has potential interactions with serotonergics such as selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants, ondansetron, meperidine, buspirone, methadone, and tramadol
Watch for s/s of serotonin syndrome

Question 16

Clinical use of Linezolid (Zyvox)?

Answer 16

Shown to have greater clinical cure rates for MRSA pneumonia compared with vancomycin.
one of only several agents that are first line for treating VRE infections

Question 17

Drug Selection Rationale for Linezolid (Zyvox)?

Answer 17

Linezolid’s use should be reserved for moderate to severe infections in which alternative antibiotics are less desirable secondary to efficacy, resistance, safety, route, or $$cost.