antibioticsbooks

chapter 10 Tetracyclines 107
administered with calcium, iron, antacids, or
multivitamins. Have patients separate these
agents by at least two hours or take a week
off from the supplements, if possible. Food
decreases the absorption of tetracycline substantially,
but of minocycline and doxycycline
minimally.
• Doxycycline does not need to be adjusted in
renal or hepatic dysfunction; tetracycline is
eliminated renally and should not be used in
cases of renal insufficiency (it can worsen renal
dysfunction).
• Tigecycline has a very large volume of distribution,
indicating that it distributes highly into
many tissues. However, it is eliminated hepatically,
achieves low urinary concentrations, and
probably should not be used for UTIs. Its extensive
distribution also leads to low bloodstream
concentrations, and it is not an ideal choice for
treating primary bloodstream infections.
• An analysis performed by the FDA across all
indications for tigecycline showed it to have a
mortality disadvantage compared to the other
antibiotics studied. This was driven largely by
a study of hospital-acquired pneumonia. While
this is obviously concerning, tigecycline still
may be useful because it has activity against
many highly drug-resistant organisms in
which there are few (or no) alternatives.
What They’re Good For
Uncomplicated respiratory tract infections: acute
exacerbations of chronic bronchitis, sinusitis,
community- acquired pneumonia. They are the drugs
of choice for many tick-borne diseases. Use as
alternative drugs for skin or soft-tissue infections,