Action

Binds with 50S subunit of susceptible bacterial ribosomes, suppressing protein synthesis in bacterial cells and causing cell death

Availability

erythromycin base

Capsules (delayed-release): 250 mg

Ointment (ophthalmic): 0.5%

Tablets: 250 mg, 500 mg

Tablets (delayed-release, enteric-coated): 250 mg, 333 mg, 500 mg

Tablets (particles in tablets): 333 mg, 500 mg

erythromycin ethylsuccinate

Oral suspension: 200 mg/5 ml, 400 mg/5 ml

Powder for suspension: 100 mg/2.5 ml, 200 mg/5 ml, 400 mg/5 ml Tablets: 400 mg

erythromycin lactobionate

Powder for injection: 500 mg, 1 g

erythromycin stearate

Tablets (film-coated): 250 mg, 500 mg

erythromycin (topical)

Gel: 2%

Ointment: 2%

Solution: 2%

Swabs: 2%

Indications and dosages

➣ Pelvic inflammatory disease

Adults: 500 mg (base) I.V. q 6 hours for 3 days, then 250 mg (base, estolate, or stearate) or 400 mg (ethylsuccinate) q 6 hours for 7 days

➣ Syphilis

Adults: 500 mg (base, estolate, or stearate) P.O. q.i.d. for 14 days

➣ Most upper and lower respiratory tract infections; otitis media; skin infections; Legionnaires' disease

Adults: 250 mg P.O. q 6 hours, or 333 mg P.O. q 8 hours, or 500 mg P.O. q 12 hours (base, estolate, or stearate); or 400 mg P.O. q 6 hours or 800 mg P.O. q 12 hours (ethylsuccinate); or 250 to 500 mg I.V. (up to 1 g) q 6 hours (gluceptate or lactobionate)

Children: 30 to 50 mg/kg/day (base, estolate, ethylsuccinate, or lactobionate) I.V. or P.O., in divided doses q 6 hours when giving I.V. and q 6 to 8 hours when giving P.O. Maximum dosage is 2 g/day for base or estolate, 3.2 g/day for ethylsuccinate, and 4 g/day for lactobionate.

➣ Intestinal amebiasis

Adults: 250 mg (base, estolate, or stearate) or 400 mg (ethylsuccinate) P.O. q 6 hours for 10 to 14 days

Children: 30 to 50 mg/kg/day (base, estolate, ethylsuccinate, or stearate) P.O. in divided doses over 10 to 14 days

➣ Prophylaxis of ophthalmia neonatorum caused by Neisseria gonorrhoeae or Chlamydia trachomatis

Neonates: 0.5- to 1-cm ribbon of ointment into each lower conjunctival sac once

➣ Treatment of conjunctivitis of the newborn caused by susceptible organisms

Neonates: 50 mg/kg/day (ethylsuccinate) P.O. in four divided doses for at least 14 days

➣ Pertussis

Children: 40 to 50 mg/kg/day (estolate preferred) P.O. in four divided doses for 14 days

➣ Pneumonia of infancy

Infants: 50 mg/kg/day (estolate or ethylsuccinate) P.O. in four divided doses for at least 3 weeks

➣ Acne

Adults and children older than age 12: 2% ointment, gel, or solution applied topically b.i.d.

Dosage adjustment

• Hepatic impairment

Off-label uses

• Chancroid

Contraindications

• Hypersensitivity to drug or tartrazine

• Concurrent use of astemizole, cisapride, pimozide, or terfenadine

• Hepatic impairment (with estolate)

• Pregnancy (with estolate)

Precautions

Use cautiously in:

• myasthenia gravis

• hepatic disease.

Administration

See Be aware that ventricular arrhythmias and sudden death may occur if drug is given concurrently with potent CYP3A inhibitors (such as clarithromycin, diltiazem, nitroimidazole antifungal agents, protease inhibitors, verapamil, and troleandomycin).

• Give erythromycin ethylsuccinate and delayed-release products without regard to meals, but avoid giving with grapefruit juice.

• Give erythromycin base or stearate 1 hour before or 2 hours after meals for optimal absorption.

• Follow label directions to reconstitute drug for I.V. use. For intermittent infusion, infuse each 250 mg in at least 100 ml of normal saline solution over 20 to 60 minutes. Continuous infusion may be given over 6 to 24 hours as directed.

Adverse reactions

CV: torsades de pointes, arrhythmias

EENT: ototoxicity

GI: nausea, vomiting, diarrhea, abdominal pain or cramps

Hepatic: hepatic dysfunction, hepatitis

Skin: rash

Other: increased appetite, aggravation of weakness in myasthenia gravis, allergic reactions, superinfection, phlebitis at I.V. site

Interactions

Drug-drug. Alfentanil, alprazolam, bromocriptine, buspirone, carbamazepine, clozapine, cyclosporine, diazepam, disopyramide, ergot alkaloids, felodipine, methylprednisolone, midazolam, tacrolimus, theophylline, triazolam, vinblastine, warfarin: increased blood levels and risk of toxicity from these drugs

Clindamycin, lincomycin: antagonism of erythromycin's effects

CYP3A inhibitors: increased erythromycin blood level, with risk of ventricular arrhythmias and sudden death

Digoxin: increased digoxin blood level

HMG-CoA reductase inhibitors: increased risk of myopathy and rhabdomyolysis

Hormonal contraceptives: decreased contraceptive efficacy

Astemizole, cisapride, pimozide, sparfloxacin, terfenadine: increased risk of serious arrhythmias

Rifabutin, rifampin: decreased erythromycin effects, increased risk of adverse GI reactions

Theophylline: increased theophylline blood level, decreased erythromycin blood level

Drug-diagnostic tests. Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, bilirubin: increased levels

Urine catecholamines: false elevations

Drug-food. Grapefruit juice: increased erythromycin blood level

Patient monitoring

• Check temperature, and watch for signs and symptoms of superinfection.

• Monitor liver function tests. Watch for signs and symptoms of hepatotoxicity.

• Assess patient's hearing for signs of ototoxicity.

Patient teaching

• Instruct patient to take with 8 oz of water 1 hour before or 2 hours after meals, and to avoid grapefruit juice.

• If drug causes GI upset, encourage patient to take it with food.

• Tell patient not to swallow chewable tablets whole and not to chew or crush enteric-coated tablets.

See Advise patient to immediately report irregular heart beats, unusual tiredness, yellowing of skin or eyes, or signs and symptoms of new infection.

• Tell patient he'll undergo periodic blood tests to monitor liver function.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and foods mentioned above.