antibioticsbooks

Tetracyclines and
Glycylcyclines
10
Agents: doxycycline, minocycline, tetracycline,
tigecycline (a glycylcycline)
Once considered broad-spectrum antibiotics, the
relentless advance of bacterial resistance and the
off-patent status of the drugs have reduced the use of
tetracyclines to niche indications. They are useful
(but not highly studied) alternatives for the treatment
of common respiratory tract infections and
drugs of choice for a variety of uncommon infections.
Doxycycline is preferred in most situations
over tetracycline and minocycline. This class may
see a revival with the introduction of the glycylcyclines
(starting with tigecycline), which evade most
tetracycline resistance mechanisms and have a
broad spectrum of activity.
Mechanism of Action
Tetracyclines and glycyclines both bind to the bacterial
ribosome at the 30S subunit, preventing the
docking of transfer RNA carrying new amino acids
for addition to the elongating protein chain.