(erythromycin · DailyMed)
RYTHROCAPS 125MG/5ML GRANULES FOR SUSPENSION
ERYTHROMYCIN
What it does
Erythromycin is an antibiotic used to treat various bacterial infections.
Commonly used for: bacterial infections, bronchitis, pneumonia, skin infections …
Read more in plain English ↓Plain-language summary for general understanding - not medical advice. Always follow your pharmacist/doctor.
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Sourcing - Kenya onlyRegistration & product details
Source: Pharmacy and Medicines Regulatory Authority · fetched 2026-04-21 17:37:47 · updated 2026-09-15 04:32:44
Drug Interactions
151Pharmacodynamic Warnings
Erythromycin appears in TABLE 9: Drugs that prolong the QT interval
Severe (14)
Antipsychotics, Second Generation - increases exposure
Erythromycin is predicted to increase the exposure to antipsychotics, second generation (cariprazine). Avoid.
Cariprazine - increases exposure
Erythromycin is predicted to increase the exposure to antipsychotics, second generation (cariprazine). Avoid.
Eletriptan - increases exposure
Erythromycin moderately increases the exposure to triptans (eletriptan). Avoid.
Ergometrine - increases risk of ergotism
Macrolides (clarithromycin) are predicted to increase the risk of ergotism when given with ergometrine. Avoid.
Ergotamine - increases risk of ergotism
Macrolides (clarithromycin) are predicted to increase the risk of ergotism when given with ergotamine. Avoid.
Moderate (38)
Alfentanil - increases exposure
Erythromycinispredictedtoincreasetheexposuretoopioids (alfentanil,buprenorphine,fentanyl,oxycodone).Monitorand adjustdose.oStudy com/codemedicalapps/ cal Applications)
Amlodipine - increases exposure
Erythromycin is predicted to increase the exposure to calcium channel blockers (amlodipine, felodipine, lacidipine, lercanidipine, nicardipine, nifedipine, nimodipine). Monitor and adjust dose.
Antiarrhythmics - increases exposure
Erythromycin is predicted to increase the exposure to antiarrhythmics (propafenone). Monitor and adjust dose.
Antiepileptics - increases concentration
Erythromycin markedly increases the concentration of antiepileptics (carbamazepine). Monitor concentration and adjust dose.
Atorvastatin - increases exposure
Erythromycins slightly increases the exposure to statins (atorvastatin). Monitor and adjust dose.
Unknown (99)
Abemaciclib - increases exposure
Erythromycin is predicted to increase the exposure to abemaciclib.
Acalabrutinib - increases exposure
Erythromycin is predicted to increase the exposure to acalabrutinib. Avoid or monitor.
Afatinib - increases exposure
Macrolides are predicted to increase the exposure to afatinib.
Alphablockers - increases exposure
Erythromycin is predicted to increase the exposure to alpha blockers (tamsulosin).
Alprazolam - increases exposure
Erythromycin is predicted to increase the exposure to benzodiazepines (alprazolam).
Data from BNF 85 (British National Formulary). This is not a substitute for professional medical advice. Matched via: exact
About this medicine
Erythromycin is an antibiotic used to treat various bacterial infections.
What it treats
- bacterial infections
- bronchitis
- pneumonia
- skin infections
- ear infections
How it works
It works by stopping the growth of bacteria, helping the body to fight off infections.
Who it's for
It is suitable for adults and children who have certain bacterial infections.
Drug class
Macrolides
Cautions
- • Be careful if you are taking other medications that can affect heart rhythm.
AI-assisted summary grounded in BNF data - general information only, not medical advice. Always confirm with your pharmacist or doctor.
Clinical monograph: Erythromycin
BNF-referencedErythromycin is a macrolide antibiotic effective against a range of bacterial infections. It works primarily by inhibiting protein synthesis in susceptible bacteria, making it a valuable choice for patients with penicillin hypersensitivity. Erythromycin is commonly used in treating respiratory tract infections, skin infections, and various other bacterial infections, including those caused by organisms like Propionibacterium acnes.
Indications
- Bacterial infections
- Acute otitis media
- Community-acquired pneumonia
- Skin and soft tissue infections
- Campylobacter enteritis
- Pertussis
- Syphilis (early stage)
- Chlamydia infections
- Impetigo
- Secondary bacterial infection of eczema
Dosage
Children: Child 1–23 months: 125 mg 4 times a day. Child 2–7 years: 250 mg 4 times a
Adults: 500 mg 4 times a day for 5 days, or alternatively 250–500 mg 4 times a day for 5–7 days.
Mechanism of action
Erythromycin exerts its antibacterial effect by binding to the 23S ribosomal RNA in the 50S subunit of bacterial ribosomes. This binding inhibits the transpeptidation and translocation steps of protein synthesis, effectively halting bacterial growth. The drug has a strong affinity for bacterial ribosomes, which contributes to its broad-spectrum activity against various pathogens.
Pharmacodynamics
Erythromycin acts as a bacteriostatic agent, preventing bacterial growth by inhibiting protein synthesis. It is effective against many strains of bacteria, although susceptibility testing is recommended due to increasing resistance. Notably, erythromycin does not impact nucleic acid synthesis and may lead to complications such as pseudomembranous colitis or hepatotoxicity in some patients.
Pharmacokinetics
Erythromycin is well-absorbed from the gastrointestinal tract, with bioavailability affected by food. It is widely distributed in body tissues, with higher concentrations in the lungs and liver. The drug undergoes hepatic metabolism and is primarily excreted in bile, with a small amount eliminated through urine. Erythromycin's half-life varies but generally ranges from 1.5 to 2 hours.
Contra-indications
- Hypersensitivity to erythromycin or any component of the formulation
- History of cholestatic jaundice or hepatic dysfunction associated with prior use of erythromycin
Adverse effects
- Gastrointestinal disturbances (nausea, vomiting, diarrhea)
- Cholestatic jaundice
- Hepatotoxicity
- Skin rashes
- QT interval prolongation
- Tinnitus
- Hearing loss (reversible)
- Pseudomembranous colitis
Interactions
- Erythromycin may significantly increase the exposure to certain drugs such as antipsychotics, simvastatin, and triptans due to its effect on cytochrome P450 enzymes
- Caution with concurrent use of drugs that prolong the QT interval
- Moderate interaction with aminophylline (decreases exposure)
Precautions
- Use with caution in patients with hepatic impairment or pre-existing liver disease
- Monitor for signs of pseudomembranous colitis in patients with diarrhea following antibiotic use
- Assess for potential drug interactions due to the impact on CYP450 metabolism
Pregnancy
Erythromycin crosses the placenta. It is generally considered safe for use during pregnancy, particularly for treating infections when no alternatives are available, but should be used with caution.
Breast-feeding
Erythromycin is excreted in breast milk. While generally considered safe, the infant should be monitored for potential side effects. Consult healthcare providers for specific recommendations.
Storage
Store in a cool, dry place away from direct sunlight. Keep out of reach of children. Check specific product information for any temperature requirements.
Formulations
- Oral suspension (125 mg/5 ml)
- Tablets (250 mg and 500 mg)
- Injectable solution (various strengths for intravenous administration)
AI-synthesized from BNF references - general information only, not a substitute for professional medical advice or the current BNF. Verify doses with a pharmacist.
Molecular reference: Erythromycin
PubChem CID 12560Molecular formula: C37H67NO13
Mechanism of action
In order to replicate, bacteria require a specific process of protein synthesis, enabled by ribosomal proteins. Erythromycin acts by inhibition of protein synthesis by binding to the 23S ribosomal RNA molecule in the 50S subunit of ribosomes in susceptible bacterial organisms. It stops bacterial protein synthesis by inhibiting the transpeptidation/translocation step of protein synthesis and by inhibiting the assembly of the 50S ribosomal subunit. This results in the control of various bacterial infections. The strong affinity of macrolides, including erythromycin, for bacterial ribosomes, supports their broad‐spectrum antibacterial activities. Macrolide antibiotics are bacteriostatic agents that inhibit protein synthesis by binding reversibly to 50S ribosomal subunits of sensitive microorganisms, at or very near the site that binds chloramphenicol. Erythromycin does not inhibit peptide bond formation per se, but rather inhibits the translocation step wherein a newly synthesized peptidyl tRNA molecule moves from the acceptor site on the ribosome to the peptidyl donor site. Gram-positive bacteria accumulate about 100 times more erythromycin than do gram-negative bacteria. Cells are considerably more permeable to the un-ionized form of the drug, which probably explains the increased antimicrobial activity at alkaline pH. ... /Erythromycin/ inhibits the growth of susceptible organisms (principally Propionibacterium acnes) on the surface of the skin and reduces the concn of free fatty acids in sebum ... The reduction in free fatty acids in sebum may be an indirect result of the inhibition of lipase-producing organisms which convert triglycerides into free fatty acids or may be a direct result of interference with lipase production in these organisms. /In acne treatment regimens/ Although stromal-derived factor-1 (SDF-1) via its cognate receptor CXCR4 is assumed to play a critical role in migration of endothelial cells during new vessel formation after tissue injury, CXCR4 expression on endothelial cells is strictly regulated. Erythromycin (EM), a 14-membered ring macrolide, has an anti-inflammatory effect that may account for its clinical benefit in the treatment of chronic inflammatory diseases. However, the effects of EM on endothelial cells and especially their expression of CXCR4 have not been fully evaluated. In this study, we demonstrated that EM markedly induced CXCR4 surface expression on microvascular endothelial cells in vitro and lung capillary endothelial cells in vivo. This ability to induce CXCR4 surface expression on endothelial cells was restricted to 14-membered ring macrolides and was not observed in other antibiotics including a 16-membered ring macrolide, josamycin. Furthermore, this EM-induced expression of CXCR4 on endothelial cells was functionally significant as demonstrated by chemotaxis assays in vitro. These findings suggest that EM-induced CXCR4 surface expression on endothelial cells may promote migration of CXCR4-expressing endothelial cells into sites of tissue injury, which may be associated with the known anti-inflammatory activity of this macrolide.
Pharmacodynamics
Macrolides, such as erythromycin, stop bacterial growth by inhibiting protein synthesis and translation, treating bacterial infections. Erythromycin does not exert effects on nucleic acid synthesis. This drug has been shown to be active against most strains of the following microorganisms, effectively treating both in vitro and clinical infections. Despite this, it is important to perform bacterial susceptibility testing before administering this antibiotic, as resistance is a common issue that may affect treatment. **A note on antimicrobial resistance, pseudomembranous colitis, and hepatotoxicity** Many strains of Haemophilus influenzae are resistant to erythromycin alone but are found to be susceptible to erythromycin and sulfonamides used in combination. It is important to note that Staphylococci that are resistant to erythromycin may emerge during erythromycin and/or sulfonamide therapy. Pseudomembranous colitis has been reported with most antibacterial agents, including erythromycin, and may range in severity from mild to life-threatening. Therefore, the physician should consider this diagnosis in patients with diarrhea after the administration of antibacterial agents. Erythromycin can cause hepatic dysfunction, cholestatic jaundice, and abnormal liver transaminases, particularly when erythromycin estolate is administered.
Biological pathways
Source: PubChem (NCBI) · pathways from PathBank, Reactome, WikiPathways & PharmGKB.
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