French pharmaceutical company Hoechst Marion Roussel (later Sanofi-Aventis) began phase II/III clinical trials of telithromycin (HMR-3647) in 1998. Telithromycin was approved by the European Commission in July 2001 and subsequently went on sale in October 2001. In the US, telithromycin received U.S. Food and Drug Administration (FDA) approval on April 1, 2004 Telithromycin is the first ketolide antibiotic to enter clinical use and is sold under the brand name of Ketek. After significant controversy regarding safety and research fraud, the US Food and Drug Administration sharply curtailed the approved uses of the drug in 2007. Telithromycin is a semi-synthetic erythromycin derivative. It is created by substituting a ketogroup for the cladinose sugar and adding a carbamate ring in the lactone ring. An alkyl-aryl moiety is attached to this carbamate ring. Furthermore, the carbon at position 6 has been methylated, as is the case in clarithromycin, to achieve better acid-stability. For the treatment of Pneumococcal infection, acute sinusitis, acute bacterial tonsillitis, acute bronchitis and bronchiolitis, lower respiratory tract infection and lobar (pneumococcal) pneumonia. KETEK tablets contain telithromycin, a semisynthetic antibacterial in the ketolide class for oral administration. Telithromycin blocks protein synthesis by binding to domains II and V of 23S rRNA of the 50S ribosomal subunit. By binding at domain II, telithromycin retains activity against gram-positive cocci (e.g., Streptococcus pneumoniae) in the presence of resistance mediated by methylases (erm genes) that alter the domain V binding site of telithromycin. Telithromycin may also inhibit the assembly of nascent ribosomal units.

Dirithromycin (Dynabac) is a macrolide glycopeptide antibiotic used to treat different types of bacterial infections, such as bronchitis, pneumonia, tonsillitis, skin infections. Dirithromycin is a semi-synthetic derivative of erythromycin - the hemi-aminal resulting from the condensation of (9S)-erythromycyclamine with 2-(2-methoxyethoxy) acetaldehyde. Being unstable under both acidic and alkaline conditions, dirithromycin functions as a more lipid-soluble prodrug for (9S)-erythromycyclamine. Erythromycylamine exerts its activity by binding to the 50S ribosomal subunits of susceptible mircoorganisms resulting in inhibition of protein synthesis. Dirithromycin has been shown to be active against most strains of the following microorganisms both in vitro and in clinical infections: Staphylococcus aureus (methicillin-susceptible strains only), Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, Legionella pneumophila, Moraxella catarrhalis, and Mycoplasma pneumoniae. Dirithromycin showed better activity in vitro against Campylobacter jejuni and Borrelia burgdorferi than erythromycin or clarithromycin but in general demonstrated less activity than erythromycin, clarithromycin, or azithromycin against a majority of microorganisms. The pharmacokinetic profile of dirithromycin has advantages over other microlides of once-daily dosing and high and prolonged tissue concentrations but adverse effect profiles similar to those of the other macrolides, with reported problems most often related to the gastrointestinal tract.

Roxithromycin is a semi-synthetic macrolide antibiotic, which was developed by Roussel Uclaf and is available in Australia. Roxithromycin prevents bacteria from growing, by interfering with their protein synthesis. Roxithromycin binds to the subunit 50S of the bacterial ribosome, and thus inhibits the translocation of peptides. It can treat respiratory tract, urinary and soft tissue infections.

Clarithromycin is an antibacterial drug which is used either in combination with lansoprazole and amoxicillin (Prevpac), in combination with omeprazole and amoxicillin (Omeclamox) or alone (Biaxin) for the treatment of broad range of infections. The drug exerts its action by binding to 23s rRNA (with nucleotides in domains II and V). The binding leads to the protein synthesis inhibition and the cell death.

Clarithromycin is an antibacterial drug which is used either in combination with lansoprazole and amoxicillin (Prevpac), in combination with omeprazole and amoxicillin (Omeclamox) or alone (Biaxin) for the treatment of broad range of infections. The drug exerts its action by binding to 23s rRNA (with nucleotides in domains II and V). The binding leads to the protein synthesis inhibition and the cell death.