Erythromycin

Drug Overview

Erythromycin is a broad-spectrum antibiotic belonging to the macrolide class, primarily used to treat bacterial infections. It exerts its bacteriostatic or bactericidal effects by inhibiting bacterial protein synthesis and is suitable for patients allergic to penicillin or infections caused by specific pathogens. This medication can treat a variety of infections including respiratory, skin, and sexually transmitted diseases, but should be used under a physician's judgment based on the specific condition.

Erythromycin has broad antimicrobial activity, targeting Gram-positive bacteria, some Gram-negative bacteria, and atypical pathogens such as Mycoplasma and Chlamydia. Its unique structure allows it to penetrate certain tissues, making it suitable for infection scenarios where other antibiotics are unsuitable. In Taiwan and Hong Kong, this medication is commonly available in capsule, tablet, or suspension forms.

Brand Names and Scientific Name

The scientific name of erythromycin is erythromycin. Major brand names include:

• ERYC®
• E.E.S.®
• PCE®

Different brands may contain different excipients, so patients should choose the appropriate formulation based on their physician’s prescription.

Drug Classification

Erythromycin belongs to the macrolide antibiotic class. These drugs are characterized by their cyclic structure that can penetrate cell membranes and have selective activity against certain pathogens. Unlike penicillins, their mechanism involves inhibiting the 50S ribosomal subunit, blocking protein synthesis. This class of drugs is often used as an alternative for patients allergic to penicillin.

Indications

Main indications include:

• Upper respiratory tract infections (e.g., tonsillitis, sinusitis)
• Lower respiratory tract infections (e.g., bronchitis, pneumonia)
• Skin and soft tissue infections (e.g., cellulitis, wound infections)

Additionally, it is used to treat non-gonococcal urethritis, syphilis, and other sexually transmitted infections, as well as for prophylaxis or treatment of certain postoperative infections.

Common Side Effects

Mild Side Effects:

• Gastrointestinal discomfort (diarrhea, nausea, abdominal pain)
• Dry mouth, dizziness
• Tongue discoloration (especially when using suspension)

These reactions usually resolve after discontinuation; if symptoms persist, consult a physician.

Serious Side Effects:

• Allergic reactions (hives, difficulty breathing)
• Hepatic dysfunction (jaundice, dark urine)
• Cardiac arrhythmias (irregular heartbeat, chest tightness)

If these symptoms occur, stop medication immediately and seek medical attention.

Warnings and Precautions

Contraindications:

• Allergy to macrolides
• Severe liver or gastrointestinal disease
• Concurrent use of certain cardiac drugs (e.g., digoxin)

Use during pregnancy and lactation requires caution:

• Pregnancy category C, use only if necessary
• May be secreted into breast milk; lactating women should evaluate risks before use

Liver Metabolism Precautions: Patients with severe hepatic impairment should have dosage adjustments and regular liver function monitoring.

Drug Interactions

Concurrent use with the following drugs may affect efficacy or increase side effects:

• Anticoagulants (warfarin): may enhance anticoagulant effects
• Ergot alkaloids (used for migraines): increased risk of toxicity
• Oral contraceptives: may reduce contraceptive effectiveness

Taking with antacids or calcium/iron supplements can reduce absorption; it is recommended to take at least 2 hours apart. When used with certain antiarrhythmic drugs (e.g., digoxin), blood levels should be monitored.

Dosage and Administration

The common adult dose is 250-500 mg orally every 6 hours; higher doses may be needed for severe infections. Pediatric doses are calculated based on weight, typically 10-15 mg per kilogram every 8 hours. Extended-release capsules should be swallowed whole and not chewed to maintain the sustained-release effect.

Follow the physician’s instructions to complete the course, even if symptoms improve; do not stop medication prematurely. Enteric-coated preparations should be taken whole to protect the gastrointestinal tract. Taking with food may reduce gastrointestinal discomfort, but adjustments should follow the medication instructions.

Missed Dose Management

If a dose is missed within 1 hour, take it immediately; if more than 1 hour has passed, skip the missed dose and resume the regular schedule. Do not double doses to make up for missed ones, as this may increase side effect risk.

Overdose Management

Overdose may cause severe diarrhea, arrhythmias, or liver dysfunction. If overdose is suspected, seek immediate medical attention and bring the medication container. Symptoms of poisoning include persistent vomiting, inability to eat, or altered consciousness, requiring emergency treatment.

 

Frequently Asked Questions

Do I need to take erythromycin with specific meal times?

It is recommended to take erythromycin 30 minutes to 1 hour after meals to reduce gastrointestinal side effects. If the medication causes significant stomach discomfort, it can be taken with food, but avoid high-fat meals as they may affect absorption.

What are common side effects of long-term erythromycin use and how can they be alleviated?

Common side effects include diarrhea, nausea, and abdominal pain. Mild symptoms can be managed by slowing the medication pace or switching to enteric-coated formulations; severe diarrhea or blood in stool warrants stopping the medication and consulting a doctor, as it may indicate pseudomembranous colitis.

What drug interactions should I be aware of when using erythromycin with other medications?

Erythromycin may interact with warfarin, cyclosporine, and other drugs, increasing blood levels and the risk of bleeding or nephrotoxicity. When taken with antacids or calcium/iron supplements, at least 2 hours should be spaced between doses to avoid absorption issues. Always inform your healthcare provider of all medications you are using.

Is erythromycin safe during pregnancy or breastfeeding?

Erythromycin is classified as pregnancy category B, generally considered safe, but should be used only if necessary after medical evaluation. It may be secreted into breast milk; risks to the infant should be assessed, and alternative medications considered if necessary.

What are alternative antibiotics for those allergic to erythromycin?

For erythromycin allergy, physicians may prescribe clindamycin, fluoroquinolones (e.g., levofloxacin), or cephalosporins, depending on the infection type and allergy severity. Do not self-medicate or switch antibiotics without medical guidance.