Ketolides
Encyclopedia
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
s belonging to the macrolide
Macrolide
The macrolides are a group of drugs whose activity stems from the presence of a macrolide ring, a large macrocyclic lactone ring to which one or more deoxy sugars, usually cladinose and desosamine, may be attached. The lactone rings are usually 14-, 15-, or 16-membered...
group. Ketolides are derived from erythromycin
Erythromycin
Erythromycin is a macrolide antibiotic that has an antimicrobial spectrum similar to or slightly wider than that of penicillin, and is often used for people who have an allergy to penicillins. For respiratory tract infections, it has better coverage of atypical organisms, including mycoplasma and...
by substituting the cladinose
Cladinose
Cladinose is a hexose deoxy sugar that in several antibiotics is attached to the macrolide ring.In ketolides, a relatively new class of antibiotics, the cladinose is replaced with a keto group.-External links:* *...
sugar with a keto-group
Ketone
In organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...
and attaching a cyclic carbamate group in the lactone
Lactone
In chemistry, a lactone is a cyclic ester which can be seen as the condensation product of an alcohol group -OH and a carboxylic acid group -COOH in the same molecule...
ring. These modifications give ketolides much broader spectrum than other macrolides. Moreover, ketolides are effective against macrolide-resistant bacteria, due to their ability to bind at two sites at the bacterial ribosome
Ribosome
A ribosome is a component of cells that assembles the twenty specific amino acid molecules to form the particular protein molecule determined by the nucleotide sequence of an RNA molecule....
as well as having a structural modification that makes them poor substrates for efflux-pump mediated resistance. Ketolides block protein synthesis by binding to ribosomal subunits and may also inhibit the formation of newly forming ribosomes.
The only ketolide on the market at this moment is telithromycin
Telithromycin
Telithromycin is the first ketolide antibiotic to enter clinical use. It is used to treat mild to moderate respiratory infections. Telithromycin is sold under the brand name of Ketek....
, which is sold under the brand name of Ketek.
Other ketolides in development include cethromycin
Cethromycin
Cethromycin is a ketolide antibiotic undergoing research for the treatment of community acquired pneumonia and for the prevention of post-exposure inhalational anthrax, and was given an "orphan drug" status for this indication. Originally discovered and developed by Abbott, it was acquired by...
and solithromycin
Solithromycin
Solithromycin is a novel ketolide antibiotic undergoing clinical development for the treatment of community acquired pneumonia and other infections...
.