Erythromycin
Trade names: Eramycin, Erythrocin
Drug class: Macrolide antibiotic Pregnancy: (Category B)
Therapeutic
actions
§ Inhibits protein synthesis of microorganisms by binding to
ribosome.
§ It is effective only against rapidly multiplying organisms.
§ Absorbed readily from the upper GIT (small intestine).
§ Are manufactured in enteric –coated or film-coated forms to
prevent destruction by gastric acid, diffuse poorly to C.S.F. & primarily
excreted in bile.
Indications
Systemic
Administration
• Acute infections caused by sensitive strains of Streptococcus pneumoniae, Mycoplasma
pneumoniae, Listeria monocytogenes, Legionella pneumophila
• URIs,
LRIs, skin and soft-tissue infections caused by group A β-hemolytic
streptococci when oral treatment is preferred to injectable benzathine
penicillin
• PID caused by N.
gonorrhoeae in patients allergic to penicillin
• In conjunction with sulfonamides in URIs caused by Haemophilus influenzae
• As an adjunct to antitoxin in infections caused by Corynebacterium diphtheriae and
Corynebacterium minutissimum
• Prophylaxis against α-hemolytic streptococcal endocarditis
before dental or other procedures in patients allergic to penicillin who have
valvular heart disease
Oral
Erythromycin
•
Treatment of intestinal
amebiasis caused by Entamoeba histolytica;
infections in the newborn and in pregnancy that are caused by Chlamydia trachomatis and in adult
chlamydial infections when tetracycline cannot be used; primary syphilis (Treponema pallidum) in
penicillin-allergic patients; eliminating Bordetella
pertussis organisms from the nasopharynx of infected individuals and as
prophylaxis in exposed and susceptible individuals.
• Unlabeled uses: erythromycin base is used with neomycin before
colorectal surgery to reduce wound infection; treatment of severe diarrhea
associated with Campylobacter enteritis
or enterocolitis; treatment of genital, inguinal, or anorectal lymphogranuloma
venereum infection; treatment of Haemophilus
ducreyi (chancroid)
Ophthalmic
Ointment
• Treatment of superficial ocular infections caused by susceptible
strains of microorganisms; prophylaxis of ophthalmia neonatorum caused by N. gonorrhoeae or C. trachomatis
Topical
Dermatologic Solutions for Acne
• Treatment of acne vulgaris
Topical
Dermatologic Ointment
• Prophylaxis against infection in minor skin abrasions
• Treatment of skin infections caused by sensitive microorganisms
Contraindications/cautions
Systemic
Administration
• Contraindication: allergy to erythromycin.
• Use cautiously with hepatic dysfunction, lactation (secreted and
may be concentrated in breast milk; may modify bowel flora of nursing infant
and interfere with fever workups).
Ophthalmic
Ointment
• Contraindications: allergy to erythromycin; viral, fungal,
mycobacterial infections of the eye.
Dosage
Available Forms:
Base: Tablets--250, 333, 500 mg; DR capsules--250 mg; ophthalmic ointment--5
mg/g. Estolate: Tablets--500 mg; capsules--250 mg; suspension--125, 250 mg/5
mL. Stearate: Tablets--200, 400 mg; suspension--200, 400 mg/5 mL, 100 mg/2---5
mL; powder for suspension-200 mg/5 mL; granules for suspension--400 mg/5 mL;
topical solution--1.5%, 2%; topical gel, ointment--2%.
Systemic
administration:
Oral preparations of the different
erythromycin salts differ in pharmacokinetics: 400 mg erythromycin
ethylsuccinate produces the same free erythromycin serum levels as 250 mg of
erythromycin base, sterate, or estolate.
Adult:
15---20 mg/kg per day in continuous IV
infusion or up to 4 g/d in divided doses q6h; 250 mg (400 mg of ethylsuccinate)
q6h PO or 500 mg q12h PO or 333 mg q8h PO, up to 4 g/d, depending on the
severity of the infection.
Streptococcal
infections:
20---50 mg/kg per day PO in divided doses
(for group A β-hemolytic streptococcal infections, continue therapy for at
least 10 d).
Legionnaire's
disease:
1---4 g/d PO or IV in divided doses (ethylsuccinate 1.6 g/d;
optimal doses not established).
Dysenteric
amebiasis:
250
mg (400 mg of ethylsuccinate) PO qid or 333 mg q8h for 10---14 d.
Acute
pelvic inflammatory disease (N. gonorrhoeae):
500 mg of lactobionate or gluceptate IV q6h
for 3 d and then 250 mg stearate or base PO q6h or 333 mg q8h for 7 d.
Pertussis:
40---50 mg/kg per day PO in divided doses for 5---14 d
(optimal dosage not established).
Prophylaxis
against bacterial endocarditis before dental or upper respiratory procedures:
1 g (1.6 g of ethylsuccinate) 6 h later.
Chlamydial
infections:
Urogenital infections during pregnancy: 500
mg PO qid or 666 mg q8h for at least 7 d, 1/2 this dose q8h for at least 14 d
if intolerant to first regimen. Urethritis in males: 800 mg of ethylsuccinate
PO tid for 7 d.
Primary
syphilis:
30---40 g (48---64 g of
ethylsuccinate) in divided doses over 10---15 d.
CDC
recommendations for STDs:
500 mg PO qid for 7---30 d, depending on the infection.
Pediatric:
30---50 mg/kg per day PO in divided doses.
Specific dosage determined by severity of infection, age and weight.
Dysenteric
amebiasis:
30---50 mg/kg per day in divided doses for 10---14 d.
Prophylaxis
against bacterial endocarditis:
20 mg/kg before procedure and then 10 mg/kg 6 h later.
Chlamydial
infections:
50 mg/kg per day PO in divided doses, for at
least 2 (conjunctivitis of newborn) or 3 (pneumonia of infancy) wk.
Ophthalmic ointment:
1/2-in ribbon instilled into conjunctival sac
of affected eye two to six times per day, depending on severity of infection.
Topical
dermatologic solution for acne:
Apply to affected areas morning and evening.
Topical
dermatologic ointment:
Apply to affected area 1---5 ×/d.
Adverse effects
Systemic
Administration
• CNS: Reversible hearing loss,
confusion, uncontrollable emotions, abnormal thinking
• GI: Abdominal cramping,
anorexia, diarrhea, vomiting, pseudomembranous colitis, hepatotoxicity
• Hypersensitivity: Allergic
reactions ranging from rash to anaphylaxis Other:
Super infections
Ophthalmic
Ointment
• Dermatologic: Edema, utricaria, dermatitis, angioneurotic edema
• Local: Irritation, burning, itching at site of application
Topical
Dermatologic Preparations
• Local: Super infections,
particularly with long-term use
Clinically important interactions
Systemic
Administration
• Drug-drug
§ Increased serum levels of digoxin
§ Increased effects of oral anticoagulants, theophyllines,
carbamazepine
§ Increased therapeutic and toxic effects of corticosteroids
§ Increased
levels of cyclosporine and risk of renal toxicity
Topical
Dermatologic Solution for Acne
• Drug-drug
§ Increased irritant effects with peeling, desquamating, or
abrasive agents
Systemic
Administration
• Drug-lab test
§ Interferes with fluorometric determination of urinary
catecholamines
§ Decreased urinary estriol levels due to inhibition of hydrolysis
of steroids in the gut
Nursing
Consideration:
Systemic
Administration
• Culture site of infection before therapy.
•
Administer oral
erythromycin base or stearate on an empty stomach, 1 h before or 2---3 h after
meals, with a full glass of water (oral erythromycin estolate, ethylsuccinate,
and certain enteric-coated tablets [see manufacturer's instructions] may be
given without regard to meals).
•
Administer around the clock
to maximize effect; adjust schedule to minimize sleep disruption.
• Monitor liver function in patients on prolonged therapy.
• Give some preparations (see above) with meals, or substitute one
of these preparations, if GI upset occurs with oral therapy.
Topical
Dermatologic Solution for Acne
• Wash affected area, rinse well, and dry before application.
Ophthalmic
and Topical Dermatologic Preparation
•
Use
topical products only when needed. Sensitization produced by the topical use of
an antibiotic may preclude its later systemic use in serious infections.
Topical antibiotic preparations not normally used systemically are best.
• Culture site before beginning therapy.
• Cover the affected area with a sterile bandage if needed
(topical).
