Source: Υπουργείο Υγείας (CY) Revision Year: 2020 Publisher: Remedica Ltd, Aharnon Str., Limassol Industrial Estate, 3056 Limassol, Cyprus
Pharmacotherapeutic Group: Antibacterials for systemic use; Macrolides, Lincosamides and Streptogramins
ATC Code: J01FA01
Erythromycin exerts its antimicrobial action by binding to the 50S ribosomal sub-unit of susceptible microorganisms and suppresses protein synthesis. Biochemical tests demonstrate erythromycin inhibits protein synthesis of the pathogen without directly affecting nucleic acid synthesis. Antagonism has been demonstrated between clindamycin and erythromycin, lincomycin and chloramphenicol.
Erythromycin is usually active against most strains of the following organisms both in vitro and in clinical infections:
Gram positive bacteria – Listeria monocytogenes, Corynebacterium diphtheriae (as an adjunct to antitoxin), Staphylococci spp, Streptococci spp (including Enterococci).
Gram negative bacteria – Haemophilus influenzae, Neisseria meningitides, Neisseria gonorrhooeae, Legionella pneumophila, Moraxella (Branhamella) catarrhalis, Bordetella pertussis, Campylobacter spp.
Mycoplasma – Mycoplasma pneumoniae, Ureaplasma urealyticum.
Other organisms – Treponema pallidum, Chlamydia spp, Clostridia spp, L-forms, the agents causing trachoma and lymphogranuloma venerum.
Note: the majority of strains of Haemophilus influenzae are susceptible to the concentrations reached after ordinary doses.
Orally administered erythromycin stearate is readily and reliably absorbed.
Optimal serum levels of erythromycin are reached when the drug is taken in the fasting state or immediately before meals. Peak blood levels normally occur within one hour of dosing of erythromycin ethylsuccinate granules. The elimination half-life is approximately two hours. Doses may be administered two, three or four times a day.
Erythromycin ethylsuccinate is less susceptible than erythromycin to the adverse effect of gastric acid. It is absorbed from the small intestine. It is widely distributed throughout body tissues. Only low concentrations are normally achieved in the spinal fluid, but passage of the drug across the blood-brain barrier increases in meningitis.
In patients with normal hepatic function, erythromycin is concentrated in the liver and excreted via the bile.The effect of hepatic dysfunction on excretion of erythromycin by liver into the bile is not known. Little metabolism occurs and only about 5% is excreted in the urine.
Long-term (2 years) oral studies conducted in rats up to about 400 mg/kg/day and in mice up to about 500 mg/kg/day with erythromycin stearate did not provide evidence of tumorigenicity. Mutagenicity studies conducted did not show any genotoxic potential, and there was no apparent effect on male or female fertility in rats treated with erythromycin (base) by oral gavage at 700 mg/kg/day. There is no evidence of teratogenicity or any other adverse effect on reproduction in female rats dosed by oral gavage at 350 mg/kg/day (7 times the human dose) of erythromycin base prior to and during mating, during gestation and through weaning.
There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used in pregnancy only if it is clearly needed.
Erythromycin has been reported to cross the placental barrier in humans, but foetal plasma levels are generally low.
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