What is erythromycin?
Erythromycin is a macrolide antibiotic. Other macrolide antibiotics include azithromycin, clarithromycin, roxithromycin.
What is erythromycin used for?
Erythromycin is prescribed by dermatologists for a variety of skin conditions including:
Erythromycin is particularly useful in individuals allergic to penicillin.
It is active against many gram-positive organisms (including Staphylococcus aureus, Streptococcus pyogenes, corynebacteria and clostridia) and some gram-negative organisms (Neisseria gonorrhoeae,). It is also effective for mycoplasma infections, syphilis and chlamydia.
Unfortunately, increasing resistance is being reported. In Hamilton, New Zealand, about 14% of Staphylococcus aureus are resistant to erythromycin.
How is erythromycin taken?
Oral erythromycin is best taken fasting or just before meals. It comes in a number of bases and formulations.
It is available in New Zealand as the base compound:
- EMU-V tablets
- Eryc capsules
The estolate salt is:
- Eromycin tablets, suspension
The ethyl succinate salt is:
- EES (can be taken after meals)
The stearate salt is:
- ERA capsules, tablets
In addition, it is available as a topical preparation for acne (Eryacne gel, Stiemycin solution).
Side effects of erythromycin
Erythromycin is generally well tolerated. It is thought that it can be used safely in pregnancy and during breast feeding.
The following side effects are uncommon.
- Gastrointestinal disturbance: nausea, vomiting, abdominal pain, diarrhoea, loss of appetite
- Liver reactions: more common in those with pre-existing liver disease and potentially serious. Signs are dark urine, light stools, yellow eyes and skin (jaundice).
- Allergic rashes: hives, fixed drug eruption, Stevens-Johnson – toxic epidermal necrolysis and rarely, anaphylaxis.
- Hearing loss: more likely on high doses in those with kidney disease.
- Life threatening arrhythmias (irregularities of the heartbeat ) have been reported in those with an electrical dysfunction that results in a prolonged Q-T interval on electrocardiograph (ECG). This can be due to congenital or acquired heart conditions or electrolyte disturbance (low potassium or magnesium levels).
Drug interactions with erythromycin
Erythromycin has important interactions with other medications. Tell your doctor the names of all medications you are taking, whether prescribed or purchased without prescription.
- Erythromycin should not be taken with terfenadine (Teldane®), astemisole (Hismanal®) or Cisapride (Prepulsid®) because it could result in dangerous irregularities of the heartbeat and sudden death. These drugs are no longer available in New Zealand. Other drugs that can prolong the Q-T interval include amiodarone, risperidone, haloperidol, citaloproma, ciprofloxacin.
Erythromycin can increase the concentration of the following medications resulting in potentially toxic levels:
- Warfarin (additional prothrombin time blood tests are necessary)
- Statins, particularly simvastatin and atorvastatin. Toxicity results in muscle pain and weakness, which may be serious. If long-term treatment with a statin and erythromycin is required, suitable alternatives are fluvastatin, pravastatin and rosuvastatin.
- Theophylline (Nuelin, Theo-24, Theo-Dur)
- Carbamazepine (Tegretol, Teril)
- Ciclosporin (Neoral)
- Ergotamine (increases peripheral ischaemia) (Cafergot, Ergodryl, Migril)
- Digoxin (Lanoxin)
- Triazolam (Halcion, Hypam, Trycam)
- Midazolam (Hypnovel injection)
- Alfentanil (Rapifen)
- Pimozide (Orap)
- Bromocryptine (Parlodel)
- Disopyramide (Rhythmodan)
- Phenytoin (Dilantin)
- Valproate (Epilim)
- Tacrolimus (Prograf)
- Quinidine (Kinidin)