New macrolides

Interest has increased recently in newer macrolides and azalides such as clarithromycin and azithromycin. These newer macrolides have much longer plasma half-lives than erythromycin, are concentrated intracellularly, and may be better tolerated than erythromycin. Clinical studies of azithromycin administered once daily and clarithromycin twice daily indicate they are effective therapy of streptococcal pharyngitis, sinusitis, and acute exacerbations of chronic bronchitis and community-acquired pneumonia. They have in vitro activity against Chlamydia pneumoniae, Chlamydia psittaci, and Mycoplasma pneumoniae, but little experience in treatment of pneumonia caused by these organisms with clarithromycin has been reported to date. Azithromycin is effective therapy as a single dose for Chlamydia trachomatis genital infections, but a single dose may not be effective against Neisseria gonorrhoeae. Preliminary information indicates that clarithromycin and azithromycin may be useful against opportunistic infections caused by Mycobacterium avium-intracellulare and other Mycobacteria, as well as Toxoplasma gondii and Cryptosporidium organisms.