What is erythromycin, and how does it work (mechanism of action)?
Erythromycin is an antibiotic in the class of antibiotics known as macrolide antibiotics which also includes azithromycin (Zithromax, Zmax) and clarithromycin (Biaxin).
Erythromycin, like all macrolide antibiotics, prevents bacterial cells from growing and multiplying by interfering with their ability to make proteins while not affecting human cells. Bacteria such as Haemophilus influenzae are resistant to erythromycin alone and must be treated with a combination of erythromycin and adequate doses of sulfonamides.
The FDA approved E.E.S in April 1965.
What are the uses for erythromycin?
Erythromycin is used to treat:
- Streptococcal infections of the throat ("strep throat") and skin
- Lung infections, for example, pneumonia caused by streptococcal pneumoniae, mycoplasma pneumoniae, and legionella pneumophila (legionnaires disease)
- Pelvic inflammatory disease
- Erythrasma
- Whooping cough
- Listeriosis
- Intestinal amebiasis
It is used for the treatment of staphylococcal infections of the skin and as an alternative antibiotic for the treatment of syphilis, gonorrhea, and chlamydia.
Erythromycin is used in patients who are allergic to penicillin for the prevention of recurrent rheumatic fever and infections of the hearts' valves (endocarditis) in patients with valvular abnormalities of the heart before they undergo dental treatments.
The non-FDA approved uses for erythromycin include acne, Lyme disease, and tetanus.
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Just about any painful sore throat is caused by strep.
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What are the side effects of erythromycin?
The most frequent side effects of erythromycin are
- nausea,
- vomiting,
- loss of appetite,
- diarrhea, and
- abdominal pain.
These gastrointestinal side effects are usually dose-related, i.e., more pronounced with higher doses.
Allergic reactions such as
- hives,
- rash, or
- anaphylaxis (a severe allergic reaction which can lead to shock and death) have been reported rarely.
What is the dosage for erythromycin? Should I take it with food?
- The usual dosage for adults is 250 mg every 6 hours, 333 mg every 8 hours or 500 mg every 12 hours. Doses may be increased up to 4 g/day according to the severity of the infection.
- In children, the usual dosage is 30 to 50 mg/kg/day with age, weight, and severity of the infection being taken into consideration to determine the appropriate dosage.
- Erythromycin may be taken with or without food; however optimal blood levels of erythromycin are obtained when taken on an empty stomach (at least 30 minutes and preferably 2 hours before or after meals).
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Which drugs or supplements interact with erythromycin?
Erythromycin when used with antiarrhythmic drugs such as, amiodarone (Cordarone), bretylium (Bretylol), disopyramide (Norpace), dofetilide (Tikosyn), procainamide (Pronestyl), quinidine (Quinaglute, Quinidex, Quinora) and sotalol (Betapace) exaggerates the effect of the antiarrhythmic drugs which may give rise to abnormal heart rhythms such as torsades de pointes.
Theophyllines such as theophylline (Theo-Dur), oxtriphylline (Choledyl SA), and aminophylline (Phyllocontin) reduce erythromycin blood levels by increasing elimination of erythromycin by the kidneys, which may reduce the effectiveness of erythromycin. Conversely, erythromycin inhibits the metabolism (breakdown) of theophyllines by the liver and causes an increase in blood levels of theophylline. High theophylline levels may give rise to side effects such as seizures and disturbances in heart rhythm. Therefore, the dose of theophyllines should be reduced or theophylline levels in the blood should be measured in patients taking erythromycin.
Combining erythromycin with ergotamine or ydroergotamine has been associated with acute ergot toxicity. This combination should be avoided.
Erythromycin prevents digoxin (Lanoxin) from being eliminated by the kidneys; this in turn causes increased levels of digoxin in the blood. Increased levels of digoxin can cause disturbances in heart rhythm. Therefore, it is important to monitor and adjust digoxin doses when treating with erythromycin.
Erythromycin prevents the elimination of warfarin (Coumadin) from the body which can raise the levels of warfarin in the blood. Warfarin is an anticoagulant or blood thinner, and an increase in its level in blood can increase the risk of bleeding. It is important to monitor the effects of warfarin and adjust warfarin doses when treating with erythromycin.
Erythromycin inhibits the breakdown of HMG-CoA reductase inhibitors (statins) such as atorvastatin (Lipitor), lovastatin (Mevacor) and simvastatin (Zocor) by the liver leading to increased levels of statins in the blood. High levels of statins could result in severe myopathy (muscle damage) with rhabdomyolysis (r (rapid breakdown of skeletal muscle) that may damage the kidneys or even lead to death. Erythromycin also can elevate blood levels of some anti-seizure drugs such as carbamazepine (Tegretol) by preventing the breakdown of the anti-seizure drug by the liver. Therefore, doses of the anti-seizure drugs may need to be reduced during treatment with erythromycin. Erythromycin also increases blood levels of sildenafil (Viagra). The dose of sildenafil should be reduced when treating with erythromycin.
Grapefruit juice may prevent the breakdown of erythromycin, resulting in elevated levels of erythromycin in the blood. Therefore, it is important to avoid eating grapefruit or drinking grapefruit juice during treatment with erythromycin.
Is erythromycin safe to take if I’m pregnant or breastfeeding?
- Erythromycin crosses the placenta, but its level in the blood of the fetus is low. There are no adequate studies in pregnant women, hence pregnant women should only use erythromycin if it is felt that the benefits of treatment outweigh the potential but unknown risks.
- Erythromycin is excreted in breast milk; however, erythromycin is considered by the American Academy of Pediatrics to be compatible with breastfeeding. Caution should be exercised, however, when erythromycin is prescribed to women who are breastfeeding.
What else should I know about erythromycin?
What preparations of erythromycin are available?
Erythromycin is available as:
- Tablets: 250, 333, 400 and 500 mg.
- Suspension: 200 and, 400 mg/teaspoon.
- Tablet (Chewable): 200 mg. Powder: 100 mg/half-teaspoon and 200 mg/teaspoon.
- Granules: 200 and 400 mg/teaspoon.
- Powder for Injection: 500 mg and 1g.
How should I keep erythromycin stored?
Erythromycin should be stored at temperatures below 86 F (30 C). It is important to protect tablets from moisture and excessive heat.