ERYTHROMYCIN†

General

Pronunciation:
eh-rith-roe-mye-sin

erythromycin base

Trade Name(s)

• E-Mycin
• Eryc 
• Ery-Tab
• PCE

erythromycin ethylsuccinate

Trade Name(s)

• E.E.S
• EryPed

erythromycin lactobionate

Trade Name(s)

• Erythrocin

erythromycin stearate

Trade Name(s)

• Erythrocin Stearate
• Erythro-S 

erythromycin (topical)

Trade Name(s)

• Erygel

Ther. Class.
anti-infectives

Pharm. Class.
macrolides

Indications

• IV PO 

  Infections caused by susceptible organisms including:

  • Upper and lower respiratory tract infections,
  • Otitis media (with sulfonamides),
  • Skin and skin structure infections,
  • Pertussis,
  • Diphtheria,
  • Erythrasma,
  • Intestinal amebiasis,
  • Pelvic inflammatory disease,
  • Nongonococcal urethritis,
  • Syphilis,
  • Legionnaires' disease,
  • Rheumatic fever.

• Useful when penicillin is the most appropriate drug but cannot be used because of hypersensitivity, including:

  • Streptococcal infections,
  • Treatment of syphilis or gonorrhea.
• Topical Treatment of acne.

Action

Suppresses protein synthesis at the level of the 50S bacterial ribosome.

Therapeutic Effect(s):

Bacteriostatic action against susceptible bacteria.

• Active against many gram-positive cocci, including:

  • Streptococci,
  • Staphylococci.

• Gram-positive bacilli, including:

  • Clostridioides,
  • Corynebacterium.

• Several gram-negative pathogens, notably:

  • Neisseria,
  • Legionella pneumophila.
• Mycoplasma and Chlamydia are also usually susceptible.

Pharmacokinetics

Absorption: Variable absorption from the duodenum after oral administration (dependent on salt form). Absorption of enteric-coated products is delayed. Minimal absorption may follow topical or ophthalmic use.

Distribution: Widely distributed. Minimal CNS penetration. Crosses placenta; enters breast milk.

Protein Binding: 70–80%.

Metabolism and Excretion: Partially metabolized by the liver, excreted mainly unchanged in the bile; small amounts excreted unchanged in the urine.

Half-life: Neonates: 2.1 hr; Adults: 1.4–2 hr.

TIME/ACTION PROFILE (blood levels)

Contraindication/Precautions

Contraindicated in:

• Hypersensitivity;
• Concurrent use of dihydroergotamine, ergotamine, lovastatin, pimozide, or simvastatin;
• Long QT syndrome
• Hypokalemia
• Hypomagnesemia
• Heart rate <50 bpm;
• Known alcohol intolerance (most topicals);
• Tartrazine sensitivity (some products contain tartrazine–FDC yellow dye #5);
• Products containing benzyl alcohol should be avoided in neonates.

Use Cautiously in:

• Liver/renal disease;
• OB:  May be used in pregnancy to treat chlamydial infections or syphilis;
• Myasthenia gravis (may worsen symptoms);
• Geri:  ↑ risk of ototoxicity if parenteral dose >4 g/day, ↑ risk of QTc interval prolongation.

Adverse Reactions/Side Effects

CNS: seizures (rare)

CV: TORSADES DE POINTES, VENTRICULAR ARRHYTHMIAS, QT interval prolongation

Derm: rash

EENT: ototoxicity

GI: CLOSTRIDIOIDES DIFFICILE-ASSOCIATED DIARRHEA (CDAD), nausea, vomiting, abdominal pain, cramping, diarrhea, hepatitis, infantile hypertrophic pyloric stenosis, pancreatitis (rare)

GU: interstitial nephritis

Local: phlebitis at IV site

Misc: HYPERSENSITIVITY REACTIONS (INCLUDING ANAPHYLAXIS)

* CAPITALS indicate life-threatening.
Underline indicate most frequent.

Interactions

Drug-Drug

• Concurrent use with  pimozide  may ↑ levels and the risk for serious arrhythmias (concurrent use contraindicated); similar effects may occur with  diltiazem,  verapamil,  ketoconazole,  itraconazole,  nefazodone, and  protease inhibitors ; avoid concurrent use.
• May ↑ levels of  ergotamine  and  dihydroergotamine  and risk for acute ergot toxicity; concurrent use contraindicated.
• Concurrent use with  lovastatin  or  simvastatin  may ↑ risk of rhabdomyolysis.
• Concurrent use with  amiodarone,  dofetilide, or  sotalol  may ↑ risk of torsades de pointe; avoid concurrent use
• May ↑  verapamil  levels and the risk for hypotension, bradycardia, and lactic acidosis.
• ↑ blood levels and effects of  sildenafil,  tadalafil, and  vardenafil ; use lower doses.
• Concurrent  rifabutin  or  rifampin  may ↓ effect of erythromycin and ↑ risk of adverse GI reactions.
• ↑ levels and risk of toxicity from  alfentanil,  alprazolam,  bromocriptine,  carbamazepine,  cyclosporine,  cilostazol,  diazepam,  disopyramide,  ergot alkaloids,  felodipine,  methylprednisolone,  midazolam,  quinidine,  rifabutin,  tacrolimus,  triazolam, or  vinblastine.
• May ↑ levels of  lovastatin  and  simvastatin  and ↑ the risk of myopathy/rhabdomyolysis.
• May ↑ serum  digoxin  levels.
•  Theophylline  may ↓ blood levels.
• May ↑  colchicine  levels and the risk for toxicity; use lower starting and maximum dose of colchicine.
• May ↑  theophylline  levels and the risk for toxicity; ↓ theophylline dose.
• May ↑  warfarin  levels and the risk for bleeding.

Route/Dosage

250 mg of erythromycin base or stearate = 400 mg of erythromycin ethylsuccinate

Most Infections

PO (Adults): Base, stearate– 250 mg every 6 hr,  or  333 mg every 8 hr,  or  500 mg every 12 hr.  Ethylsuccinate– 400 mg every 6 hr  or  800 mg every 12 hr.

PO (Children >1 mo): Base and ethylsuccinate– 30–50 mg/kg/day divided every 6–8 hr (max = 2 g/day as base or 3.2 g/day as ethylsuccinate).  Stearate– 30–50 mg/kg/day divided every 6 hr (max = 2 g/day).

PO (Neonates  ): Ethylsuccinate– 20–50 mg/kg/day divided every 6–12 hr.

IV (Adults): 250–500 mg (up to 1 g) every 6 hr.

IV (Children >1 mo): 15–50 mg/kg/day divided every 6 hr (max = 4 g/day).

Acne

Topical (Adults and Children  >12 yr): 2% gel, solution, or pledgets twice daily.

Availability (generic available)

Erythromycin Base

Delayed-release capsules: 250 mg , 333 mg 

Delayed–release tablets: 250 mg, 333 mg, 500 mg

Erythromycin Ethylsuccinate

Oral suspension (fruit, cherry, orange, or banana flavor): 200 mg/5 mL, 400 mg/5 mL

Tablets: 400 mg

Erythromycin Lactobionate

Powder for injection (requires reconstitution and dilution): 500 mg/vial, 1 g 

Erythromycin Stearate

Film-coated tablets: 250 mg

Erythromycin Topical Preparations

Gel: 2%

Pledgets: 2%

Solution: 2%

In Combination with: benzoyl peroxide (Benzamycin). See combination drugs.

Assessment

• Assess for infection (vital signs; appearance of wound, sputum, urine, and stool; WBC) at beginning of and during therapy.
• Obtain specimens for culture and sensitivity before initiating therapy. First dose may be given before receiving results.
• Monitor bowel function. Diarrhea, abdominal cramping, fever, and bloody stools should be reported to health care professional promptly as a sign of Clostridioides difficile-associated diarrhea (CDAD). May begin up to several wk following cessation of therapy.

Lab Test Considerations:

Monitor liver function tests periodically on patients receiving high-dose, long-term therapy.

• May cause ↑ serum bilirubin, AST, ALT, and alkaline phosphatase concentrations.
• May cause false ↑ of urinary catecholamines.

Potential Diagnoses

• Risk for infection (Indications)  (Side Effects) 
• Noncompliance (Patient/Family/Teaching) 

Implementation

• PO 

  Administer around the clock.  Erythromycin film-coated tablets (base and stearate)  are absorbed better on an empty stomach, at least 1 hr before or 2 hr after meals; may be taken with food if GI irritation occurs.  Enteric-coated erythromycin (base)  may be taken without regard to meals.  Erythromycin ethylsuccinate  is best absorbed when taken with meals. Take each dose with a full glass of water.

  • Use calibrated measuring device for liquid preparations. Shake well before using.
  • Do not crush or chew delayed-release capsules or tablets; swallow whole.  Erythromycin base delayed-release capsules may be opened and sprinkled on applesauce, jelly, or ice cream immediately before ingestion. Entire contents of the capsule should be taken.

• Topical Cleanse area before application. Wear gloves during application.

Patient/Family Teaching

• Instruct patient to take medication around the clock and to finish the drug completely as directed, even if feeling better. Take missed doses as soon as remembered, with remaining doses evenly spaced throughout day. Advise patient that sharing of this medication may be dangerous.
• May cause nausea, vomiting, diarrhea, or stomach cramps; notify health care professional if these effects persist or if severe abdominal pain, yellow discoloration of the skin or eyes, darkened urine, pale stools, or unusual tiredness develops. May cause infantile hypertrophic pyloric stenosis in infants; notify health care professional if vomiting and irritability occur.
• Caution patient to notify health care professional if fever and diarrhea occur, especially if stool contains blood, pus, or mucus. Advise patient not to treat diarrhea without consulting health care professional. May occur up to several wk after discontinuation of medication.
• Advise patient to report signs of superinfection (black, furry overgrowth on the tongue; vaginal itching or discharge; loose or foul-smelling stools).
• Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected, or if breast feeding.
• Instruct patient to notify health care professional if symptoms do not improve.

Evaluation/Desired Outcomes

• Resolution of the signs and symptoms of infection. Length of time for complete resolution depends on the organism and site of infection.
• Improvement of acne lesions.