Erythromycin stearate is an antibiotic belonging to the macrolide group and acts by inhibition of protein synthesis of the micro organisms. It produces peak plasma levels in one to four hours, depending on the rapidity of gastric emptying. The level declines after four to six hours. The antibiotic is concentrated in the liver and excreted in active form in the bile. About 2-5% of the drug is excreted in the urine, also in the active form. It diffuses readily in most body fluids, mainly in pleural and peritoneal fluids. Passage of the antibiotic across the bloodbrain barrier is increased in meningeal inflammation. It crosses the placental barrier but foetal plasma levels are low (5-20% of maternal plasma levels).
For the prophylaxis and treatment of infections caused by erythromycin-sensitive organisms. Erythromycin is highly effective in the treatment of a great variety of clinical infections such as:
- Upper respiratory tract infections: tonsillitis, peritonsillar abscess, pharyngitis, laryngitis, sinusitis, secondary infections in influenza and common colds.
- Lower respiratory tract infections: tracheitis, acute and chronic bronchitis, pneumonia (lobar pneumonia, bronchopneumonia, primary atypical pneumonia).
- Ear infection: otitis media and otitis externa, mostoiditis.
- Oral infections: gingivitis, Vincent’s angina
- Eye infections: blepharitis
- Skin and soft tissue infections: boils and carbuncles, paronychia, abscesses, pustular acne, impetigo, cellulitis, erysipelas.
- Gastrointestinal infections: cholecystitis, staphylococcal enterocolitis
- Prophylaxis: pre- and post- operative trauma, burns, rheumatic fever
- Other infections: osteomyelitis, urethritis, gonorrhoea, syphilis, lymphogranuloma venereum, diphtheria, prostatitis, scarlet fever.
Patients with impaired liver function or patients who have developed jaundice or other symptoms of liver toxicity during previous treatment with an erythromycin. Known hypersensitivity to erythromycin.
Blood and lymphatic system disorders: eosinophilia.
Cardiac disorders: QT interval prolongation, torsades de pointes, palpitations, and cardiac rhythm disorders including ventricular tachyarrhythmias
Gastrointestinal disorders: the most frequent side effects of oral erythromycin preparations are gastrointestinal and are dose related. The following have been reported: upper abdominal discomfort,, nausea, vomiting, diarrhoea, pancreatitis, anorexia, infantile hypertrophic pyloric stenosis. Pseudomembraneous colitis has been rarely reported in association with erythromycin therapy.
General disorders and administration site conditions: chest pain, fever, malaise
Hepatobiliary disorders: cholestatic hepatitis, jaundice, hepatic dysfunction, hepatomegaly, hepatic failure, hepatocellular hepatitis.
Immune system disorders: allergic reactions ranging from urticaria and mild skin eruptions to anaphylaxis have occurred.
Investigations: Increased liver enzyme values.
Nervous system disorders: There have been isolated reports of transient central nervous system side effects including confusion, seizures and vertigo; however, a cause and effect relationship has not been established.
Psychiatric disorders: hallucinations
Renal and urinary disorders: interstitial nephritis
Skin and subcutaneous tissue disorders: skin eruptions, pruritus, urticaria, exanthema, angioedema, Stevens-Johnson syndrome, toxic epidermal necrolysis, erythema multiforme.
Vascular disorders: hypotension
Erythromycin should not be given concomitantly with chloramphenicol or thiamphenicol. Erythromycin may potentiate the action of carbamazepine, cyclosporin, corticosteroids, digoxin, theophylline and warfarin, probably by inhibition of their hepatic metabolism.
Erythromycin may interfere with some diagnostic tests including measurement of urinary catecholamines, 17-hydroxycosteroids and 17-ketosteroids and with the microbiological measurement of blood folate. To avoid the ototoxicity of erythromycin in patients with renal failure, it is suggested that the daily dosage should not exceed 15g in patients with serum creatinine above 180 micromol per litre, hearing acuity should be tested before and during treatment, especially in the elderly; and erythromycin should not be given with other potentially ototoxic medicines.
There have been reports of excessive prolongation of prothrombin times in patients receiving erythromycin concurrently with chronic coumarin type anti-coagulant therapy. Such patients, particularly the elderly, may be at risk for developing bleeding due to this interaction. In patients receiving erythromycin during chronic treatment with a coumarin-type anticoagulant, prothrombin times should be monitored closely and the coumarin-type anticoagulant dosage adjusted accordingly.
Development of bacterial strains resistant to erythromycin is more common during prolonged treatment of infections more difficult to eradicate.
Dosage and duration of treatment
In streptococcal infections, erythromycin stearete should be administered at therapeutic dosage for at least 10 days. For continuous prophylaxis of streptococcal infections or rheumatic fever recurrences in persons with a history of rheumatic heart disease, the dose is 250mg twice a day. When used prior to surgery to prevent endocarditis a recommended schedule for adults is 1g before the procedure and 500mg every 6 hours for 8 doses after the procedure.
Treatment of primary syphilis: 2-4 grams per day given in divided doses over a period of 10 to 15 days
Treatment of gonorrhoea: 500mg four times daily for 5 days.
Posology and mode of administration
In order to obtain optimal blood levels, Erythromycin should be given on an empty stomach.
Erythromycin is given orally.
Pregnancy and lactation
There are no adequate and well-controlled studies in pregnant women. However, observational studies in humans have reported cardiovascular malformations after exposure to medicinal products containing erythromycin during early pregnancy. Erythromycin has been reported to cross the placenta barrier in humans, but foetal plasma levels are generally low. Erythromycin is excreted in breast milk, therefore, caution should be exercised when erythromycin is administered to a nursing mother.
Peak blood levels normally occur within one hour of dosing of erythromycin ethylsuccinate granules. The elimination half-life is approximately two hours. It is widely distributed throughout body tissues. Little metabolism occurs and only about 5% is excreted in the urine. It is excreted principally by the liver.
Increase in serum concentrations of the following drugs metabolised by the cytochrome P450 system may occur when administered concurrently with erythromycin: acenocoumarol, alfentanil, astemizole, bromocriptine, carbamazepine, cilostazol, cyclosporin, digoxin, dihydroergotamine, disopyramide, ergotamine, hexobarbitone, methylprednisolone, midazolam, omeprazole, phenytoin, quinidine, rifabutin, sildenafil, tacrolimus, terfenadine, theophylline, triazolam, valproate, vinblastine, and antifungals e.g., Fluconazole, ketoconazole and itraconazole.
Drugs that induce CYP3A4 (such as rifampicin, phenytoin, carbamazepine, phenobarbital) may induce the metabolism of erythromycin. This may lead to sub-therapeutic levels of erythromycin and a decreased effect.
Contraceptives: some antibiotics may in rare cases decrease the effect of contraceptive pills by interfering with the bacterial hydrolysis of steroid conjugates in the intestine and thereby re-absorption of unconjugated steroid.
Erythromycin significantly alters the metabolism of terfenadine, astemizole and primozide when taken concomitantly.
Protease inhibitors: in concomitant administration of erythromycin and protease inhibitors, an inhibition of the decomposition of erythromycin has been observed.
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.
Cimetidine may inhibit the metabolism of erythromycin which may lead to an increased plasma concentration. Erythromycin has been reported to decrease the clearance of zopiclone and thus may increase the pharmacodynamic effects of this drug.
symptoms of over dosage include nausea, vomiting and diarrhoea. The treatment consists of symptomatic and supportive care
For adults: 250mg to 500mg every 6 hours depending on the severity of the infection.
For children: The basic recommendation ranges from 30 to 50 mg/kg/day or more. Depending on the severity of the infections; these amounts are administered in four divided dose.
Erythromycin is primarily a bacteriostatic antibiotic with a broad spectrum of action, which was recommended in the treatment of wide variety of infections caused by susceptible organisms.
It has been used in cases such as: bronchitis, gastroenteritis, Campylobacter, severe diphtheria, Legionnaire’s disease Legionella and other infections, neonatal conjunctivitis, pertussis, pneumonia, sinusitis and in combination with neomycin.
Erythromycin can be administered in lieu of penicillin in patients allergic to penicillin with a variety of conditions including coal, prophylaxis of endocarditis, leptospirosis, otitis media (usually with a sulphonylurea such as sulfisoxazole), pharyngitis and prevention of rheumatic fever and skin infections, staphylococcus and streptococcus.
Effect on ability to drive and use machines: not known