PEDIAMYCIN 400
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PEDIAMYCIN 400 (PEDIAMYCIN 400).
Erythromycin binds to the 50S subunit of the bacterial ribosome and inhibits protein synthesis by blocking the translocation step.
| Metabolism | Primarily hepatic via CYP3A4 isoenzyme; undergoes demethylation and glucuronidation. |
| Excretion | Renal (80-90% unchanged); biliary/fecal (minor, <5%) |
| Half-life | 1.5-2 hours; prolonged in renal impairment (up to 6 hours) |
| Protein binding | 60-70% (primarily albumin) |
| Volume of Distribution | 0.6-0.8 L/kg; widespread distribution, including lungs and liver |
| Bioavailability | Oral: 25-35% (first-pass metabolism) |
| Onset of Action | Oral: 1-2 hours; intravenous: immediate |
| Duration of Action | 6-8 hours; prolonged in hepatic or renal dysfunction |
400 mg orally every 6 hours for 10 days.
| Dosage form | SUSPENSION |
| Renal impairment | No adjustment required for GFR >10 mL/min; for GFR ≤10 mL/min, administer 400 mg every 12 hours. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50% every 8 hours; Child-Pugh C: reduce dose by 75% every 12 hours. |
| Pediatric use | 12.5 mg/kg orally every 6 hours for 10 days; maximum 400 mg per dose. |
| Geriatric use | No specific dose adjustment, but monitor renal function and consider lower end of dosing interval; reduce dose if GFR <30 mL/min. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PEDIAMYCIN 400 (PEDIAMYCIN 400).
| Breastfeeding | Erythromycin is excreted into breast milk with an M/P ratio of approximately 0.5. Low concentrations are unlikely to cause adverse effects in nursing infants, but may theoretically alter gastrointestinal flora or cause diarrhea. Caution is advised; monitor infant for GI symptoms. |
| Teratogenic Risk | PEDIAMYCIN 400 (erythromycin) is classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, but there are no adequate controlled studies in pregnant women. In first trimester, cross placental barrier; no known teratogenic effects. In second and third trimesters, risk of infantile hypertrophic pyloric stenosis (IHPS) if exposed near term or postnatally. Avoid use in pregnancy unless clearly needed. |
■ FDA Black Box Warning
Increased risk of infantile hypertrophic pyloric stenosis (IHPS) in neonates exposed to erythromycin; avoid use in neonates <6 weeks of age.
| Serious Effects |
["Hypersensitivity to erythromycin or any macrolide antibiotic","Concurrent use with ergotamine or dihydroergotamine (acute ergot toxicity)","History of QT prolongation or concurrent use of QT-prolonging drugs (e.g., certain antipsychotics, antiarrhythmics)"]
| Precautions | ["Risk of QT prolongation and cardiac arrhythmias (e.g., torsades de pointes); avoid with other QT-prolonging drugs.","May exacerbate myasthenia gravis.","Hepatic impairment may require dose adjustment.","Monitor for superinfection with prolonged use.","Avoid in neonates due to IHPS risk."] |
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| Fetal Monitoring | Monitor maternal liver function tests and hearing in cases of prolonged therapy. For fetal monitoring, assess for signs of fetal distress if used for prolonged periods. In neonates exposed near term, monitor for signs of IHPS (projectile vomiting, poor feeding). |
| Fertility Effects | No known adverse effects on fertility in animal studies. Erythromycin does not alter reproductive hormones. May be used in patients undergoing fertility treatments without expected impact. |