antibioticsbooks

126 PART 2 Antibacterial Drugs
Spectrum
Good: MSSA, MRSA, streptococci, Enterococcus
faecium (including vancomycin-resistant strains)
Poor: Enterococcus faecalis, anything Gramnegative
Adverse Effects
Quinupristin/dalfopristin can cause phlebitis and
ideally should be administered via a central line. It
is also associated with a high incidence of myalgias
and arthralgias that can limit tolerance to therapy.
Quinupristin/dalfopristin also inhibits cytochrome
P450 3A4, so clinicians need to be aware of potential
drug interactions.
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Important Facts
• Quinupristin/dalfopristin must be mixed and
administered with 5% dextrose in water (D5W)
solutions only. When mixed with normal saline,
the drug becomes insoluble and can crystallize,
even when a patient’s IV line is flushed with
saline. Be sure that your patient’s nurses know
to flush the line with D5W or another salinefree
diluent. The drug is not available orally.
• The arthralgias and myalgias associated with
quinupristin/dalfopristin are significant and
should not be underestimated. It may be possible
to decrease their severity by decreasing
the dose, but this could compromise efficacy.
• The indication for the treatment of
vancomycin-resistant Enterococcus faecium
infections was recently removed from the labeling
of quinuprisin/dalfopristin due to a lack of
follow-up data after the initial approval.