Erythromycin is available in enteric-coated tablets, slow-release capsules, oral suspensions, ophthalmic solutions, ointments, gels, and injections.


Brand names include Robimycin, E-Mycin, E.E.S. Granules, E.E.S.-200, E.E.S.-400, E.E.S.-400 Filmtab, Erymax, Ery-Tab, Eryc, Erypar, EryPed, Eryped 200, Eryped 400, Erythrocin Stearate Filmtab, Erythrocot, E-Base, Erythroped, Ilosone, MY-E, Pediamycin, Zineryt, Abboticin, Abboticin-ES, Erycin, PCE Dispertab, Stiemycine and Acnasol.

Erythromycin may possess bacteriocidal activity, particularly at higher concentrations[1]. The mechanism is not fully elucidated however. By binding to the 50S subunit of the bacterial 70S rRNA complex, protein synthesis and subsequently structure/function processes critical for life or replication are inhibited[2]. Erythromycin interferes with aminoacyl translocation, preventing the transfer of the tRNA bound at the A site of the rRNA complex to the P site of the rRNA complex. Without this translocation, the A site remains occupied and thus the addition of an incoming tRNA and its attached amino acid to the nascent polypeptide chain is inhibited. This interferes with the production of functionally useful proteins and is therefore the basis of antimicrobial action.

Erythromycin is easily inactivated by gastric acid; therefore, all orally-administered formulations are given as either enteric-coated or more-stable laxatives or esters, such as erythromycin ethylsuccinate. Erythromycin is very rapidly absorbed, and diffuses into most tissues and phagocytes. Due to the high concentration in phagocytes, erythromycin is actively transported to the site of infection, where, during active phagocytosis, large concentrations of erythromycin are released.

Roxithromycin is a semi-synthetic macrolide antibiotic. It is used to treat respiratory tract, urinary and soft tissue infections. Roxithromycin is derived from erythromycin, containing the same 14-membered lactone ring. However, an N-oxime side chain is attached to the lactone ring. It is also currently undergoing clinical trials for the treatment of male-pattern hair loss.

Roxithromycin is available under several brandnames, for example Surlid, Rulide, Biaxsig, Roxar and Roximycin. Roxithromycin is not available in the United States. Roxithromycin has also been tested to possess antimalarial activity.

Chloramphenicol is a bacteriostatic antimicrobial originally derived from the bacterium Streptomyces venezuelae, isolated by David Gottlieb, and introduced into clinical practice in 1949.


It was the first antibiotic to be manufactured synthetically on a large scale. Chloramphenicol is effective against a wide variety of microorganisms; it is still very widely used in low income countries because it is exceedingly cheap, but has fallen out of favour in the West due to a very rare but very serious side effect: aplastic anemia.