Film-coated Tablets
Rx only
To reduce the development of drug-resistant bacteria and maintain the effectiveness of ERYTHROCIN STEARATE Film-coated tablets and other antibacterial drugs, ERYTHROCIN STEARATE Film-coated tablets should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.
DESCRIPTION
ERYTHROCIN STEARATE Film-coated tablets (erythromycin stearate tablets, USP) are an antibacterial product containing the stearate salt of erythromycin in a unique film coating.
Erythromycin is produced by a strain of Saccharopolyspora erythraea (formerly Streptomyces erythraeus) and belongs to the macrolide group of antibiotics. It is basic and readily forms salts with acids. Erythromycin is a white to off-white powder, slightly soluble in water, and soluble in alcohol, chloroform, and ether. Erythromycin stearate is known chemically as erythromycin octadecanoate. The molecular formula of erythromycin stearate is C37 H67 NO13 •C18H36O2 , and the molecular weight is 1018.43. The structural formula is:
Inactive Ingredients
250 mg tablet: Cellulosic polymers, corn starch, D&C Red No. 7, polacrilin potassium, polyethylene glycol, povidone, propylene glycol, sodium carboxymethylcellulose, sodium citrate, sorbic acid, sorbitan monooleate and titanium dioxide.
CLINICAL PHARMACOLOGY
Orally administered erythromycin base and its salts are readily absorbed in the microbiologically active form. Interindividual variations in the absorption of erythromycin are, however, observed, and some patients do not achieve optimal serum levels. Erythromycin is largely bound to plasma proteins. 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 crosses the placental barrier, but fetal plasma levels are low. The drug is excreted in human milk. Erythromycin is not removed by peritoneal dialysis or hemodialysis.
In the presence of normal hepatic function, erythromycin is concentrated in the liver and is excreted in the bile; the effect of hepatic dysfunction on biliary excretion of erythromycin is not known. After oral administration, less than 5% of the administered dose can be recovered in the active form in the urine.
Orally administered ERYTHROCIN STEARATE tablets are readily and reliably absorbed. Optimal serum levels of erythromycin are reached when the drug is taken in the fasting state or immediately before meals.
Microbiology
Erythromycin acts by inhibition of protein synthesis by binding 50 S ribosomal subunits of susceptible organisms. It does not affect nucleic acid synthesis. Antagonism has been demonstrated in vitro between erythromycin and clindamycin, lincomycin, and chloramphenicol.
Many strains of Haemophilus influenzae are resistant to erythromycin alone, but are susceptible to erythromycin and sulfonamides used concomitantly.
Staphylococci resistant to erythromycin may emerge during a course of erythromycin therapy. Erythromycin has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections as described in the INDICATIONS AND USAGE section.
Gram-positive organisms:
-
Corynebacterium diphtheriae
Corynebacterium minutissimum
Listeria monocytogenes
Staphylococcus aureus(resistant organisms may emerge during treatment)
Streptococcus pneumoniae
Streptococcus pyogenes
-
Gram-negative organisms:
-
Bordetella pertussis
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.
Erythromycin exhibits in vitro minimal inhibitory concentrations (MIC's) of 0.5 µg/mL or less against most (≥ 90%) strains of the following microorganisms; however, the safety and effectiveness of erythromycin in treating clinical infections due to these microorganisms have not been established in adequate and well-controlled clinical trials.
Gram-positive organisms:
-
Viridans group streptococci
-
Gram-negative organisms:
-
Moraxella catarrhalis
-
Susceptibility Tests
Dilution Techniques
Quantitative methods are used to determine antimicrobial minimum inhibitory concentrations (MIC's). These MIC's provide estimates of the susceptibility of bacteria to antimicrobial compounds. The MIC's should be determined using a standardized procedure. Standardized procedures are based on a dilution method1(broth or agar) or equivalent with standardized inoculum concentrations and standardized concentrations of erythromycin powder. The MIC values should be interpreted according to the following criteria:
|
MIC (µg/mL) |
Interpretation |
|
≤0.5 |
Susceptible (S) |
|
1-4 |
Intermediate (I) |
|
≥8 |
Resistant (R) |
A report of "Susceptible" indicates that the pathogen is likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable. A report of "Intermediate" indicates that the result should be considered equivocal, and, if the microorganism is not fully susceptible to alternative, clinically feasible drugs, the test should be repeated. This category implies possible clinical applicability in body sites where the drug is physiologically concentrated or in situations where high dosage of drug can be used. This category also provides a buffer zone which prevents small uncontrolled technical factors from causing major discrepancies in interpretation. A report of "Resistant" indicates that the pathogen is not likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable; other therapy should be selected.
Standardized susceptibility test procedures require the use of laboratory control microorganisms to control the technical aspects of the laboratory procedures. Standard erythromycin powder should provide the following MIC values:
|
Microorganism |
MIC (µg/mL) |
|
S. aureus ATCC 29213 |
0.12-0.5 |
|
E. faecalis ATCC 29212 |
1-4 |
Diffusion Techniques
Quantitative methods that require measurement of zone diameters also provide reproducible estimates of the susceptibility of bacteria to antimicrobial compounds. One such standardized procedure2 requires the use of standardized inoculum concentrations. This procedure uses paper disks impregnated with 15-µg erythromycin to test the susceptibility of microorganisms to erythromycin.
Reports from the laboratory providing results of the standard single-disk susceptibility test with a 15-µg erythromycin disk should be interpreted according to the following criteria:
|
Zone Diameter (mm) |
Interpretation |
|
≥23 |
Susceptible (S) |
|
14-22 |
Intermediate (I) |
|
≤13 |
Resistant (R) |
Interpretation should be as stated above for results using dilution techniques. Interpretation involves correlation of the diameter obtained in the disk test with the MIC for erythromycin.
As with standardized dilution techniques, diffusion methods require the use of laboratory control microorganisms that are used to control the technical aspects of the laboratory procedures. For the diffusion technique, the 15-µg erythromycin disk should provide the following zone diameters in these laboratory test quality control strains:
|
Microorganism |
Zone Diameter (mm) |
|
S. aureus ATCC 25923 |
22-30 |
INDICATIONS AND USAGE
To reduce the development of drug-resistant bacteria and maintain the effectiveness of ERYTHROCIN STEARATE Film-coated tablets and other antibacterial drugs, ERYTHROCIN STEARATE Film-coated tablets should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.
ERYTHROCIN STEARATE tablets are indicated in the treatment of infections caused by susceptible strains of the designated micro organisms in the diseases listed below:
Upper respiratory tract infections of mild to moderate degree caused by Streptococcus pyogenes; Streptococcus pneumoniae; Haemophilus influenzae (when used concomitantly with adequate doses of sulfonamides, since many strains of H. influenzaeare not susceptible 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®Lactobionate-I.V. (erythromycin lactobionate for injection, USP) followed by erythromycin base orally, as an alternative drug in 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 followup 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.
When tetracyclines are contraindicated or not tolerated, erythromycin is indicated for the treatment of nongonococcal urethritis caused by Ureaplasma urealyticum.
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).3 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).3
CONTRAINDICATIONS
Erythromycin is contraindicated in patients with known hypersensitivity to this antibiotic.
Erythromycin is contraindicated in patients taking terfenadine, astemizole, pimozide or cisapride. (See PRECAUTIONS - Drug Interactions.)
WARNINGS
There have been reports of hepatic dysfunction, including increased liver enzymes, and hepatocellular and/or cholestatic hepatitis, with or without jaundice, occurring in patients receiving oral erythromycin products.
There have 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 (CDAD) has been reported with use of nearly all antibacterial agents, including ERYTHROCIN® STEARATE Film-coated 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 eva luation should be instituted as clinically indicated.
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.)
PRECAUTIONS
General
Prescribing ERYTHROCIN STEAR
