Erythromycin

ADMINISTRATION ROUTES:

PO, NG, IV

ALTERNATIVE NAMES:

E-mycin

ICU INDICATIONS:

1. Empirical treatment of atypical pneumonia
2. Treatment of infections caused by other susceptible organisms
3. Prokinetic

PRESENTATION AND ADMINISTRATION:

PO:

E-Mycin 400 mg tablets (pink)

E-Mycin 200 Suspension 200 mg/5 mL (pink), E-Mycin 400 Suspension 400 mg/5 mL (pink) ERA 250 mg tablets (white)

ERA 500 mg tablets (white)

IV:

1 gm vial of powder

Add 20 mL of Water for injection ONLY to 1 gm vial

Shake until all of powder has dissolved; this may take up to 4 minutes. Vial contains 50 mg/mL.

Add required dose to compatible IV fluid to give a concentration between 1 mg/mL and 5 mg/mL. When being administered through a central line in ICU, 5 mg/mL is preferred.

Administer over 60 minutes. For patients with high risk of cardiac arrhythmia infusion should be administered over 2 hours. Risk factors for cardiac arrhythmias due to erythromycin are as follows:

• history of cardiac disease
• long QT syndrome
• quinidine, procainamide or disopyramide
• impaired hepatic metabolism
• hypokalaemia or hypomagnesaemia

Once reconstituted, solution is compatible with the following IV fluids:

Normal saline, Hartmanns

Reconstituted solution containing 50 mg/mL is stable for 24 hours at room temperature. When further diluted with saline or Hartmanns, solutions should be used within 8 hours

DOSAGE:

IV:

To treat susceptible infection:

1 gm QID

As prokinetic:

125 - 250 mg QID

PO / NG:

500 mg QID

Note: erythromycin has prokinetic effects irrespective of whether it is administered intravenously or enterally

DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:

Dose in renal impairment

Dose in renal replacement therapy

DOSAGE IN PAEDIATRICS:

IV / PO / NG:

To treat susceptible infection:

15-25 mg/kg QID

As prokinetic:

2 mg/kg TDS

CLINICAL PHARMACOLOGY:

Erythromycin belongs to the macrolide group of antibiotics. Erythromycin acts by inhibition of protein synthesis in susceptible organisms by reversibly binding to 50 S ribosomal subunits, thereby inhibiting translocation of aminoacyl transfer-RNA and inhibiting polypeptide synthesis.

Erythromycin is usually active against the following organisms in vitro and in clinical infections:

• Streptococcus pyogenes (group A Beta-haemolytic streptococci)
• Alpha-haemolytic streptococci (viridans group)
• Staphylococcus aureus (resistant organisms may emerge during treatment)
• Streptococcus pneumoniae
• Mycoplasma pneumoniae
• Treponema pallidum
• Corynebacterium diphtheriae
• Corynebacterium minutissimum
• Entamoeba histolytica
• Listeria monocytogenes
• Neisseria gonorrhoeae
• Bordetella pertussis
• Legionella pneumophila (Legionnaires' disease)
• Ureaplasma urealyticum
• Chlamydia trachomatis

The prokinetic action is through agonism at motilin receptors in the stomach antrum and upper duodenum. This induces activity of the migratory motor complex, propagating stomach contents into the small intestine.

CONTRAINDICATIONS:

1. Hypersensitivity to erythromycin

WARNINGS:

Hepatic dysfunction:

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.

Pseudomembranous colitis:

Pseudomembranous colitis has been reported with nearly all antibacterial agents, including erythromycin, and may range in severity from mild to life threatening. Therefore, it is important to consider this diagnosis in patients who present with diarrhoea subsequent to the administration of antibacterial agents.

PRECAUTIONS:

General:

There have been reports that erythromycin may aggravate the weakness of patients with myasthenia gravis

Laboratory Tests:

No tests in addition to routine ICU tests are indicated

Drug/Laboratory Test Interactions:

Erythromycin interferes with the fluorometric determination of urinary catecholamines

IMPORTANT DRUG INTERACTIONS IN ICU:

Erythromycin use in patients who are receiving high doses of theophylline may be associated with an increase in serum theophylline levels and potential theophylline toxicity. In case of theophylline toxicity and/or elevated serum theophylline levels, the dose of theophylline should be reduced while the patient is receiving concomitant erythromycin therapy.

Concomitant administration of erythromycin and digoxin has been reported to result in elevated digoxin serum levels.

There have been reports of increased anticoagulant effects when erythromycin and oral anticoagulants were used concomitantly. Increased anticoagulation effects due to interactions of erythromycin with various oral anticoagulents may be more pronounced in the elderly.

Erythromycin has been reported to decrease the clearance of triazolam and midazolam and thus may increase the pharmacologic effect of these benzodiazepines.

The use of erythromycin in patients concurrently taking drugs metabolised by the cytochrome P450 system may be associated with elevations in serum levels of these other drugs. There have been reports of interactions of erythromycin with carbamazepine, cyclosporin, tacrolimus, hexobarbital, phenytoin, alfentanil, cisapride, disopyramide, lovastatin, bromocriptine, valproate, terfenadine, and astemizole. Serum concentrations of drugs metabolised by the cytochrome P450 system should be monitored closely in patients concurrently receiving erythromycin.

ADVERSE REACTIONS:

Body as a Whole:

Anaphylaxis

Gastrointestinal System:

Nausea, vomiting, abdominal pain, diarrhoea and anorexia. Symptoms of hepatitis, hepatic dysfunction and/or abnormal liver function test results may occur

Cardiovascular System:

Rarely, erythromycin has been associated with the production of ventricular arrhythmias, including ventricular tachycardia and torsades de pointes, in individuals with prolonged QT intervals

Local:

Thrombophlebitis