antibioticsbooks

110 PART 2 Antibacterial Drugs
Spectrum
Good: atypicals, Haemophilus influenzae,
Moraxella catarrhalis, Helicobacter pylori,
Mycobacterium avium
Moderate: S. pneumoniae (telithromycin .
macrolides), S. pyogenes
Poor: staphylococci, enteric GNRs (azithromycin .
clarithromycin), anaerobes, enterococci
Adverse Effects
Gastrointestinal: Significant GI adverse effects
(nausea, vomiting, diarrhea) have been associated
with the macrolides. Erythromycin is the
worst offender—it is employed as a prokinetic
agent for patients with impaired GI motility.
Hepatic: Rare but serious adverse hepatic events
have been associated with the macrolides.
Telithromycin has been associated with
hepatic failure leading to death or the need for
transplantation.
Cardiac: Prolongation of the QT interval has been
seen with the macrolides, again most commonly
with erythromycin. Use with caution
in patients with preexisting heart conditions,
those on antiarrhythmic drugs, or those taking
interacting drugs (see below).
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Important Facts
• Drug interaction alert! These drugs (with
the exception of azithromycin) are potent
inhibitors of drug-metabolizing cytochrome
P450 enzymes. Be sure to screen your patient’s
regimen with a computerized drug interaction