Erythromycin

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:

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

Erythromycin is particularly useful in individuals allergic to penicillin and in children that are too young for a tetracycline.

It is active against many gram-positive organisms (including Staphylococcus aureus, Streptococcus pyogenes, corynebacteria and clostridia) and some gram-negative organisms (Neisseria gonorrhoeae, the cause of gonorrhoea). It is also effective for mycoplasma infections, syphilis and chlamydia.

Increasing bacterial resistance to erythromycin is reported.  The prolonged use of erythromycin has been questioned in dermatology because it can lead to bacterial resistance to the pathogen, Staphylococcus aureus (see MRSA), as well as resistance to acne bacteria (Cutibacterium acnes).

How does erythromycin work in skin diseases?

• Erythromycin has bacteriostatic effects and prevents the proliferation of bacteria.
• It inhibits pro-inflammatory cytokines such as IL-8 and decreases neutrophil oxidative bursts.

How is erythromycin taken?

Oral erythromycin is best-taken fasting or just before meals. It comes in a number of bases and formulations.

• Base compound
• Estolate salt
• Ethyl succinate salt
• Stearate salt

It is also available as a topical preparation for acne. To reduce antibiotic resistance, a non-antibiotic compound such as benzoyl peroxide or a topical retinoid should be applied when using topical erythromycin.

What are the side effects of erythromycin?

Erythromycin is generally well tolerated. When essential, erythromycin can be used in pregnancy and during breastfeeding.

The following side effects may arise.

• 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 a prescription.

• Erythromycin should not be taken with terfenadine, astemizole or cisapride 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, citalopram and 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.
• Caffeine
• Theophylline 
• Carbamazepine 
• Ciclosporin 
• Ergotamine (increases peripheral ischaemia)  
• Digoxin 
• Triazolam  
• Midazolam  
• Alfentanil 
• Pimozide 
• Bromocryptine 
• Disopyramide 
• Phenytoin  
• Valproate  
• Tacrolimus 
• Quinidine