Erythromycin exerts its antimicrobial action by binding to the 50s ribosomal sub-unit of susceptible microorganisms and suppresses protein synthesis. Erythromycin may be either bacteriostatic or bactericidal depending upon its serum concentration and the susceptibility of the micro-organism.
The in-vitro antibacterial spectrum of pathogens usually sensitive to Erythromycin is as follows (In-vitro sensitivity does not necessarily imply in vivo efficacy)
- Gram-positive aerobes: Listeria monocytogenes, Crynebacterium diphtheria, Staphylococci spp, Streptococci spp
- Gram-negative aerobes: Neisseria gonorrhoeae, Legionella pneumophila, Moraxella catarrhalis, Bordetella pertussis, Campylobacter spp.
- Mycoplasma pneumonia, Ureaplasma urealyticum, Treponema pallidum, Chlamydia spp, Clostridia spp, L-forms, the agents causing trachoma and lymphogranuloma venereum
- Oral infections
- Respiratory tract infections (including legionnaire’s disease)
- Whooping cough
- Campylobacter enteritis
- Non-gonococcal urethritis
- Skin infections
- Chronic prostatitis
- Prophylaxis of diphtheria
- Group A streptococcal infection
- Acne vulgaris and rosacea
Adult and children over 8 years: 250-500 mg every 6 hours or 0.5-1 g every 12 hours up to 4g daily in divided doses in severe infections Early syphilis: 500mg, 4 times daily for 14 days Uncomplicated genital chlamydia, non-gonococcal urethritis: 500 mg twice daily for 14 days Lyme disease: 500 mg 4 times daily for 14-21 days Renal impairment: max 1.5 g daily
Known hypersensitivity to erythromycin or any other macrolides. Use is contraindicated in acute porphyria
Common: Nausea, vomiting, diarrhea and abdominal discomfort.
Less common: hepatotoxicity (including cholestatic jaundice) and rash
Rare or very rare: Pancreatitis, antibiotic associated colitis, QT interval prolongation, arrhythmias, hearing loss (reversible). Tinnitus, Stevens-Johns syndrome, myasthenia like syndrome and toxic epidermal necrolysis
Erythromycin increases plasma concentration of alfentanil, disopyramide, dronedarone. Concurrent administration with erythromycin should be avoided due to increased risk of toxicity and side-effects. Erythromycin enhances plasma concentration of carbamazepine, loratadine, rupatadine, darifenacin, clozapine, quetiapine, buspirone, zopiclone, digoxin, cilostazole, everolimus, eplerenone, eletriptan, pravastatin, galantamine, sildenafil, sirolimus, tacrolimus, tadalafil, theophylline, verdenafil, concomitant use should be avoided.
Precautions and warnings
Erythromycin is excreted principally by the liver, so caution should be exercised in administering the antibiotic to patients with impaired hepatic function or concomitantly receiving potentially hepatotoxic agents
Pseudomembraneous colitis has been reported with nearly all antibacterial agents, including macrolides, and may range in severity from mild to life-threatening.
Treatment with antibacterial agents alters the normal flora of the colon, which may lead to overgrowth of C.difficile or other non-susceptible micro-organisms. There have been reports that erythromycin may aggravate the weakness of patients with myasthenia gravis Rhabdomyolysis with or without renal impairment has been reported in seriously ill patients receiving erythromycin concomitantly with statins
Pregnancy and lactation
Erythromycin is reported to cross placental barrier in humans as well as it is excreted in breast milk. Although Erythromycin is reported no to be harmful in pregnant and nursing mothers, caution should be exercised when erythromycin is administered to a nursing and pregnant mothers