Drug Groups

approved

Description

Erythromycin is a macrolide antibiotic produced by Streptomyces erythreus. It inhibits bacterial protein synthesis by binding to bacterial 50S ribosomal subunits; binding inhibits peptidyl transferase activity and interferes with translocation of amino acids during translation and assembly of proteins. Erythromycin may be bacteriostatic or bactericidal depending on the organism and drug concentration.

Indication

For use in the treatment of infections caused by susceptible strains of microorganisms in the following diseases: respiratory tract infections (upper and lower) of mild to moderate degree, pertussis (whooping cough), as adjunct to antitoxin in infections due to Corynebacterium diphtheriae, in the treatment of infections due to Corynebacterium minutissimum, intestinal amebiasis caused by Entamoeba histolytica, acute pelvic inflammatory disease caused by Neisseria gonorrhoeae, skin and soft tissue infections of mild to moderate severity caused by Streptococcus pyogenes and Staphylococcus aureus, primary syphilis caused by Treponema pallidum, infections caused by Chlamydia trachomatis, nongonococcal urethritis caused by Ureaplasma urealyticum, and Legionnaires' disease caused by Legionella pneumophila.

Pharmacology

Erythromycin is produced by a strain of Streptomyces erythraeus and belongs to the macrolide group of antibiotics. After absorption, erythromycin diffuses readily into most body fluids. In the absence of meningeal inflammation, low concentrations are normally achieved in the spinal fluid, but the passage of the drug across the blood-brain barrier increases in meningitis. Erythromycin is excreted in breast milk. The drug crosses the placental barrier with fetal serum drug levels reaching 5 - 20% of maternal serum concentrations. Erythromycin is not removed by peritoneal dialysis or hemodialysis.

Toxicity

Symptoms of overdose include diarrhea, nausea, stomach cramps, and vomiting.

Affected Organisms

Biotransformation

Hepatic. Extensively metabolized - after oral administration, less than 5% of the administered dose can be recovered in the active form in the urine. Erythromycin is partially metabolized by CYP3A4 resulting in numerous drug interactions.

Absorption

Orally administered erythromycin base and its salts are readily absorbed in the microbiologically active form. Topical application of the ophthalmic ointment to the eye may result in absorption into the cornea and aqueous humor.

Half Life

0.8 - 3 hours

Protein Binding

Erythromycin is largely bound to plasma proteins, ranging from 75 - 95% binding depending on the form.

References

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