ceptible to the erythromycin concentrations ordinarily achieved). (see appropriate sulfonamide labeling for prescribing information.) lower respiratory tract infections of mild to moderate severity caused by streptococcus pyogenes or streptococcus pneumoniae . listeriosis caused by listeria monocytogenes . respiratory tract infections due to mycoplasma pneumoniae . skin and skin structure infections of mild to moderate severity caused by streptococcus pyogenes or staphylococcus aureus (resistant staphylococci may emerge during treatment). pertussis (whooping cough) caused by bordetella pertussis . erythromycin is effective in eliminating the organism from the nasopharynx of infected individuals, rendering them noninfectious. some clinical studies suggest that erythromycin may be helpful in the prophylaxis of pertussis in exposed susceptible individuals. diphtheria: infections due to corynebacterium diphtheriae , as an adjunct to antitoxin, to prevent establishment of carriers and to eradicate the organism in carriers. erythrasma: in the treatment of infections due to corynebacterium minutissimum . intestinal amebiasis caused by entamoeba histolytica (oral erythromycins only). extraenteric amebiasis requires treatment with other agents. acute pelvic inflammatory disease caused by neisseria gonorrhoeae : erythrocin tm lactobionate i.v. (erythromycin lactobionate for injection, usp) followed by erythromycin base orally, as an alternative drug treatment of acute pelvic inflammatory disease caused by n. gonorrhoeae in female patients with a history of sensitivity to penicillin. patients should have a serologic test for syphilis before receiving erythromycin as treatment of gonorrhea and a follow-up serologic test for syphilis after 3 months. erythromycins are indicated for treatment of the following infections caused by chlamydia trachomatis : conjunctivitis of the newborn, pneumonia of infancy, and urogenital infections during pregnancy. when tetracyclines are contraindicated or not tolerated, erythromycin is indicated for the treatment of uncomplicated urethral, endocervical, or rectal infections in adults due to chlamydia trachomatis . 3 when tetracyclines are contraindicated or not tolerated, erythromycin is indicated for the treatment of nongonococcal urethritis caused by ureaplasma urealyticum . 3 primary syphilis caused by treponema pallidum . erythromycin (oral forms only) is an alternative choice of treatment for primary syphilis in patients allergic to the penicillins. in treatment of primary syphilis, spinal fluid should be examined before treatment and as part of the follow-up after therapy. legionnaires’ disease caused by legionella pneumophila . although no controlled clinical efficacy studies have been conducted, in vitro and limited preliminary clinical data suggest that erythromycin may be effective in treating legionnaires’ disease. prophylaxis prevention of initial attacks of rheumatic fever penicillin is considered by the american heart association to be the drug of choice in the prevention of initial attacks of rheumatic fever (treatment of streptococcus pyogenes infections of the upper respiratory tract e.g., tonsillitis, or pharyngitis). 1 erythromycin is indicated for the treatment of penicillin-allergic patients. the therapeutic dose should be administered for ten days. prevention of recurrent attacks of rheumatic fever penicillin or sulfonamides are considered by the american heart association to be the drugs of choice in the prevention of recurrent attacks of rheumatic fever. in patients who are allergic to penicillin and sulfonamides, oral erythromycin is recommended by the american heart association in the long-term prophylaxis of streptococcal pharyngitis (for the prevention of recurrent attacks of rheumatic fever). 1

been reports suggesting that erythromycin does not reach the fetus in adequate concentration to prevent congenital syphilis. infants born to women treated during pregnancy with oral erythromycin for early syphilis should be treated with an appropriate penicillin regimen. clostridium-difficile associated diarrhea clostridium difficile associated diarrhea (cdad) has been reported with the use of nearly all antibacterial agents, including erythromycin tablets, and may range in severity from mild diarrhea to fatal colitis. treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of c. difficile . c. difficile produces toxins a and b which contribute to the development of cdad. hypertoxin producing strains of c. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. cdad must be considered in all patients who present with diarrhea following antibiotic use. careful medical history is necessary since cdad has been reported to occur over two months after the administration of antibacterial agents. if cdad is suspected or confirmed, ongoing antibiotic use not directed against c. difficile may need to be discontinued. appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of c. difficile , and surgical evaluation should be instituted as clinically indicated. drug interactions serious adverse reactions have been reported in patients taking erythromycin concomitantly with cyp3a4 substrates. these include colchicine toxicity with colchicine; rhabdomyolysis with simvastatin, lovastatin, and atorvastatin; and hypotension with calcium channel blockers metabolized by cyp3a4 (e.g., verapamil, amlodipine, diltiazem) (see precautions – drug interactions ). there have been post-marketing reports of colchicine toxicity with concomitant use of erythromycin and colchicine. this interaction is potentially life-threatening, and may occur while using both drugs at their recommended doses (see precautions – drug interactions ). rhabdomyolysis with or without renal impairment has been reported in seriously ill patients receiving erythromycin concomitantly with lovastatin. therefore, patients receiving concomitant lovastatin and erythromycin should be carefully monitored for creatine kinase (ck) and serum transaminase levels. (see package insert for lovastatin.)

erapeutic dosage of erythromycin should be administered for at least ten days. the american heart association suggests a dosage of 250 mg of erythromycin orally, twice a day in long-term prophylaxis of streptococcal upper respiratory tract infections for the prevention of recurring attacks of rheumatic fever in patients allergic to penicillin and sulfonamides. 1 conjunctivitis of the newborn caused by chlamydia trachomatis oral erythromycin suspension 50 mg/kg/day in 4 divided doses for at least 2 weeks. 3 pneumonia of infancy caused by chlamydia trachomatis although the optimal duration of therapy has not been established, the recommended therapy is oral erythromycin suspension 50 mg/kg/day in 4 divided doses for at least 3 weeks. urogenital infections during pregnancy due to chlamydia trachomatis although the optimal dose and duration of therapy have not been established, the suggested treatment is 500 mg of erythromycin by mouth four times a day on an empty stomach for at least 7 days. for women who cannot tolerate this regimen, a decreased dose of one erythromycin 500 mg tablet orally every 12 hours or 250 mg by mouth four times a day should be used for at least 14 days. 3 for adults with uncomplicated urethral, endocervical, or rectal infections caused by chlamyia trachomatis, when tetracycline is contraindicated or not tolerated 500 mg of erythromycin by mouth four times a day for at least 7 days. 3 for patients with nongonococcal urethritis caused by ureaplasma urealyticum when tetracycline is contraindicated or not tolerated 500 mg of erythromycin by mouth four times a day for at least seven days. 3 primary syphilis 30 to 40 g given in divided doses over a period of 10 to 15 days. acute pelvic inflammatory disease caused by n. gonorrhoeae 500 mg erythrocin tm lactobionate-i.v. (erythromycin lactobionate for injection, usp) every 6 hours for 3 days, followed by 500 mg of erythromycin base orally every 12 hours for 7 days. intestinal amebiasis adults 500 mg every 12 hours or 250 mg every 6 hours for 10 to 14 days. children 30 to 50 mg/kg/day in divided doses for 10 to 14 days. pertussis although optimal dosage and duration have not been established, doses of erythromycin utilized in reported clinical studies were 40 to 50 mg/kg/day, given in divided doses for 5 to 14 days. legionnaires’ disease although optimal dosage has not been established, doses utilized in reported clinical data were 1 to 4 g daily in divided doses.

ring loss occurring chiefly in patients with renal insufficiency and in patients receiving high doses of erythromycin.

% of the administered dose can be recovered in the active form in the urine. optimal blood levels are obtained when erythromycin tablets are given in the fasting state (at least ½ hour and preferably 2 hours before meals). microbiology mechanism of action erythromycin acts by inhibition of protein synthesis by binding 50s ribosomal subunits of susceptible organisms. it does not affect nucleic acid synthesis. resistance the major route of resistance is modification of the 23s rrna in the 50s ribosomal subunit to insensitivity while efflux can also be significant. interactions with other antimicrobials antagonism exists in vitro between erythromycin and clindamycin, lincomycin, and chloramphenicol. antimicrobial activity erythromycin has been shown to be active against most isolates of the following bacteria both in vitro and in clinical infections as described in the indications and usage section. gram-positive bacteria: corynebacterium diphtheriae corynebacterium minutissimum listeria monocytogenes staphylococcus aureus (resistant organisms may emerge during treatment) streptococcus pneumoniae streptococcus pyogenes gram-negative bacteria: bordetella pertussis haemophilus influenzae legionella pneumophila neisseria gonorrhoeae other microorganisms: chlamydia trachomatis entamoeba histolytica mycoplasma pneumoniae treponema pallidum ureaplasma urealyticum the following in vitro data are available, but their clinical significance is unknown. at least 90% of the following bacteria exhibit in vitro minimum inhibitory concentrations (mic) less than or equal to the susceptible breakpoint for erythromycin. however, the efficacy of erythromycin in treating clinical infections due to these bacteria has not been established in adequate and well controlled clinical trials. gram-positive bacteria: viridans group streptococci gram-negative bacteria: moraxella catarrhalis susceptibility testing for specific information regarding susceptibility test interpretive criteria and associated test methods and quality control standards recognized by fda for this drug, please see: https://www.fda.gov/stic.