The FDA has announced that it is requiring changes in the labeling of the macrolide antibiotic azithromycin (Zithromax, Zmax) to warn about the risk of QT prolongation and cardiac arrhythmias.1 The new warnings are based on a retrospective study in The New England Journal of Medicine (reviewed previously in The Medical Letter2), which found that among patients who received 347,795 prescriptions for azithromycin, there were 29 cardiovascular deaths, a significantly higher rate than the 42 that occurred among patients who received 1,348,672 prescriptions for amoxicillin (which does not prolong...

Recently published results of a large, carefully conducted retrospective study indicated that use of the antibiotic azithromycin (Zithromax, and others) may increase the risk of cardiovascular death, especially in patients with a high baseline risk of cardiovascular disease.1 One possible mechanism is prolongation of the QT interval, which is known to occur rarely with azithromycin and more frequently with the other macrolide antibiotics erythromycin (Erythrocin, and others) and clarithromycin (Biaxin, and others).Among the patients who received 347,795 prescriptions for azithromycin, there...

Dirithromycin (Dynabac - manufactured by Lilly, distributed by Bock), an oral macrolide antibiotic chemically similar to erythromycin, clarithromycin (Biaxin) and azithromycin (Zithromax), has been approved for marketing by the US Food and Drug Administration (FDA).

The severity and rapid spread of COVID-19 (caused by SARS-CoV-2) have raised questions about the use of some drugs in patients with the disease and whether currently available drugs could be effective in treating it. Definitive answers are lacking, but some recommendations can be made. For additional information on specific drugs, see our table Some Drugs Being Considered for Treatment of COVID-19.

The FDA has approved rifamycin (Aemcolo – Cosmo/ Aries), a minimally absorbed oral antibiotic, for treatment of adults with travelers' diarrhea (TD) caused by noninvasive strains of Escherichia coli. It is not recommended for treatment of diarrhea that is complicated by fever and/or bloody stools. Topical and injectable formulations of rifamycin have been used in Europe for other indications for many years.

The CDC recently reported that fluoroquinoloneresistant strains of Neisseria meningitidis have been detected for the first time in the US in an area around the border of North Dakota and Minnesota (CDC. MMWR, Feb 22, 2008). These isolates were all serogroup B, for which meningococcal vaccines (Med Lett Drugs Ther 2005; 47:29) do not offer protection. Since many laboratories do not test N. meningitidis for antimicrobial susceptibility, it is possible that such resistance is more widespread. A single oral dose of ciprofloxacin (Cipro, and others) 500 mg has been used for prophylaxis after close...

The CDC has reported that many states are experiencing a higher-than-usual incidence of pertussis this year. The highest incidence has been in infants, but the disease has also occurred in older children, adolescents, and adults. Thirteen pertussis-related deaths were reported through August 24; the majority of these were in infants <3 months old.

View the Expanded Table: Antibiotics for Travelers' Diarrhea

Clarithromycin (Biaxin - Abbott) and azithromycin (Zithromax - Pfizer), two macrolide antibiotics chemically related to erythromycin, have been approved by the US Food and Drug Administration for treatment of respiratory, skin, and skin structure infections. Azithromycin has also been approved for treatment of nongonococcal urethritis and cervicitis caused by Chlamydia trachomatis.

Cefdinir (Omnicef - Parke-Davis), a third-generation oral cephalosporin, has been approved by the FDA for treatment of acute sinusitis, otitis media, acute exacerbations of chronic bronchitis, pharyngitis, community-acquired pneumonia and skin infections. Other drugs available for these indications are reviewed in The Medical Letter Handbook of Antimicrobial Therapy, 1998.