Erythromycin

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Erythromycin :
Trade names: Eramycin, Erythrocin

Drug class: Macrolide antibiotic

Pregnancy: (Category

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).