Most of macrolides are antibiotics inhibiting protein synthesis by blocking microbial ribosome. Ketolides are especially effective as they bind to two ribosomal sites. The drugs tacrolimus, pimecrolimus, and sirolimus, which are used as immunosuppressants or immunomodulators, are also macrolides. They have similar activity to ciclosporin.
- Azithromycin - unique; does not inhibit CYP3A4; approved by FDA
- Clarithromycin - approved by FDA
- Erythromycin - approved by FDA
- Fidaxomicin - approved by FDA
- Telithromycin - approved by FDA
- Cethromycin - ketolide undergoing research for the treatment of pneumonia
- Carbomycin A - minor ketolide antibiotic approved for veterinary use
- Midecamycin/midecamycin acetate
- Solithromycin - fluoroketolide, not yet approved
- Spiramycin - approved in the EU, and in other countries
- Troleandomycin - used in Italy and Turkey
- Tylosin/tylocine - used in animals
- Polyene antimycotics, including amphotericin B, nystatin
MAcrolides can differ in their macrocyclic ring (modified to create clarithromycin (Biaxin©) and azithromycin (Zithromax©) with improved pharmacokinetic properties) and sugars. For telithromycin (Ketek®), the sugar at the 3-position was removed and replaced with a keto group - hence the class name of ketolides - and an additional modification allowed for binding to a secondary site on the bacterial ribosome, resulting in enhanced activity against resistant strains.