[Macrolides. New therapeutic prospects].

The aim of the development of semisynthetic derivatives was to overcome the problem of chemical stability of erythromycin A in acid medium, with less variability in gastro-intestinal absorption and leading to renewed interest in macrolides. The new macrolides have the same antibacterial spectrum as erythromycin A including Gram-positive and Gram-negative cocci, intracellular bacteria, mycoplasma, Campylobacter sp., Helicobacter pylori, mycobacteria spp., Gram-negative bacilli including Haemophilus influenzae, Bordetella pertussis, Pasteurella multocida, Gram-positive bacilli including Corynebacterium diphtheriae and anaerobic species. In vitro activity against Haemophilus influenzae is still a controversial subject. Macrolides are among the best tolerated antibacterial agents. Theoretically, macrolides could be given to a large range of patients even those suffering from underlying diseases. The new macrolides, roxithromycin, azithromycin, clarithromycin, dirithromycin, rokitamycin and miokamycin, are indicated for the treatment of upper respiratory tract infections and lower respiratory tract infections due to intracellular bacteria or Mycoplasma pneumoniae. Macrolides could be used as first line therapy for non-gonococcal urethritis, especially those due to Chlamydia trachomatis or Ureaplasma urealyticum. In pelvic inflammatory infections in which Chlamydia trachomatis is involved macrolides could also be used. Other non-conventional indications under discussion are H. pylori and Lyme's disease. Macrolides in combination with other antibacterials could be an alternative for Mycobacterium avium-intracellulare infections. The antiparasite effect of erythromycin has been known since the 1950s. Extensive experimental work is currently underway to determine the potential use of these drugs in this setting. Research during the 80s in the macrolide field, led to enhanced pharmacokinetic properties. Current research is focused on expanding the antibacterial spectrum and to overcome cross-resistance among 14-membered-ring macrolides.