Erythromycin belongs to the macrolide group of antibiotics. It acts by inhibition of protein synthesis by binding 50 S ribosomal subunits of susceptible organisms.

Erythromycin is usually active against the following organisms in vitro and in clinical infections: Streptococcus pyogenes (group A Beta-hemolytic streptococci), Staphylococcus aureus (Resistant organisms may emerge during treatment.), Streptococcus pneumoniae, Mycoplasma pneumoniae, Treponema pallidum, Corynebacterium diphtheriae, Corynebacterium minutissimum, Entamoeba histolytica, Listeria monocytogenes, Neisseria gonorrhoeae, Bordetella pertussis, Legionella pneumophila, Ureaplasma urealyticum, Chlamydia trachomatis. Erythromycin is widely distributed throughout body tissues and fluids. Erythromycin is excreted in high concentrations in bile.

Erythromycin is contraindicated in patients with known hypersensitivity to this antibiotic.

Erythromycin is indicated for the treatment of the following infections: Lower Respiratory Tract Infection due to Mycoplasma pneumoniae, Pertussis (whooping cough), Skin and soft tissue infections, septicemia.

Erythromycin is indicated in treatment of syphilis. It is the drug of choice for the Legionnaire's disease also for acute pelvic inflammatory disease. For topical application, erythromycin is only available as an ointment. A common application of this ointment is treatment of staphylococcal eyelid infections.

Deaths and cardiac arrhythmias have been reported with concomitant administration of terfenadine and erythromycin. There have been reports of increased anticoagulant effects when erythromycin and oral anticoagulants were used concomitantly. Do not take erythromycin with theophylline, digoxin, ergotamine or dihydroergotamine. It increases their plasmatic concentration. Erytromycin antagonize lincomicin, clindamycin and cloramfenicol effects.

Erythromycin is well absorbed and may be given without regard to meals.

• Adults: The usual dose is 250 mg 4 times daily, in severe infections 4g/day.
• Children: 20-40mg/kg/day 4 divided doses, for more severe infections doses may be doubled. Erythromycin skin ointment is applying on affected skin 2-3 times daily. Trachoma and inclusion conjunctivitis in older children or adults can also be effectively treated with oral erythromycin with a 3-week course of 2 g daily in 4 divided doses.

In case of overdose the patients can have allergic reactions. The treatment: Adrenaline, Gastric evacuation; Symptomatic therapy.

Erythromycin is excreted in human milk. Caution should be exercised when erythromycin is administered to a nursing woman. Erythromycin is excreted by the liver. Caution should be exercised when erythromycin is administered to patients with impaired hepatic function (as it is principally excreted by the live). Prolonged or repeated use of erythromycin may result superinfections.

The most frequent side effects of oral erythromycin preparations are gastrointestinal. They include nausea, vomiting, abdominal pain, diarrhea, anorexia and allergic reactions.