Erythromycin

Erythromycin is a macrolide antibiotic prescribed by dermatologists for a variety of skin conditions including:

• Acne
• Rosacea
• Erythrasma
• Pityriasis lichenoides
• Infections such as impetigo or boils.

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.

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)
• E-mycin

The stearate salt is:

• ERA capsules, tablets

In addition, it is available as a topical preparation for acne (Eryacne gel, Stiemycin solution).

Side Effects

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).

Drug interactions

Erythromycin can interact 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.

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.
• Caffeine
• 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)