Erythromycin
is produced by a strain of Streptomyces Erythraeus and belongs to the macrolide
group of antibiotics. It is basic and readily forms salts with acids. The base,
the stearate salt and the esters are poorly soluble in water. Erythromycin ethylsuccinate
is an ester of erythromycin suitable for oral administration.
Erythromycin may be considered as the prototype of antibiotics as it has the effect of preventing protein synthesis at bacterial ribosomes, resulting in the death of the organism.
Erythromycin appears to inhibit protein synthesis in susceptible organisms by reversibly binding to ribosomal subunits, thereby inhibiting translocation of aminoacyl transfer-RNA and inhibiting polypeptide synthesis.
Erythromycin may be used for the treatment of the pneumonias such as legionella pneumonia and Pneumococcal pneumonia and provides a good alternative to the tetracyclines for chlamydial infections and mycoplasms. However, haemopilus influenzae are usually resistant. It may also be used for the treatment of streptococcal pharyngitis, skin infections (eryspela, impetigo) and erythrasma.
Erythromycin has a similar effect as tetracyclines against acne; it can be used both systemically (by mouth) and topically (applied direct to affected area). It is also known to be effective against chlamydial infections in the genito-urinary tract and eyes (conjuctivitus).
Erythromycin often (in 5 to 30% of the cases) causes gastrointestinal pain, (nausea, vomiting, gastric pain, and abdominal cramps). High single doses are not suitable; children experience adverse reactions more frequently. There seem to be hepatotoxic reactions with all erythromycin preparations, but they are reversible after the discontinuation of the drug. The transaminases increase in about 10%; jaundice appears in only 1 of 1000 treated subjects. Ototoxic effects are also infrequent and reversible (hearing loss, ringing in the ear). Other rare side effects include skin reactions, nephritis, fever and eosinophilia, pancreatitis, colitis, and myasthenia.
Its
use is considered safe in pregnant women, however it is known to increase the
risk of hepatitis during pregnancy. It has been found in relatively large quantities
in breast milk. Despite it being known to cause hypersensitivity and alteration
of the intestinal flora, it can be given to nursing mothers but with a reduced
dose. The dose should also be reduced for patients with advanced renal failure
as there may be an increased risk of ototoxic effects. In this case doses should
be reduced by up to fifty percent. Erythromycin should not be given to patients
with a liver disorder due to its potential hepatotoxicity.
(click on 3D image right to view interactive 3D structure)
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