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 |
| Molecular Weight | 733.93 |
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 | Avoid unless clearly needed; erythromycin estolate has been associated with increased risk of pyloric stenosis in infants if used after the first trimester, but data in first trimester is limited. No known teratogenicity. |
| 2nd trimester | Use with caution; may be used if benefit outweighs risk. Monitor for maternal hepatotoxicity (erythromycin estolate). |
| 3rd trimester | Use with caution near delivery; may cause adverse effects in neonate (e.g., pyloric stenosis). Avoid prolonged use. |
Clinical note
Comprehensive clinical and safety monograph for PEDIAMYCIN 400 (PEDIAMYCIN 400).
| Placental transfer | Erythromycin crosses the placenta; fetal concentrations are approximately 20-50% of maternal serum concentrations. |
| Breastfeeding | Erythromycin is excreted into breast milk in small amounts. Considered compatible with breastfeeding; however, monitor infant for gastrointestinal disturbances (e.g., diarrhea, rash). Theoretical risk of pyloric stenosis in infants less than 2 months of age. |
■ 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 antibioticConcomitant use with ergotamine or dihydroergotaminePre-existing liver disease or hepatic impairment (for erythromycin estolate)Prolonged QT interval or concurrent use with drugs that prolong QT interval
| 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. |
| Food/Dietary | Avoid grapefruit and grapefruit juice during treatment as it can increase erythromycin levels. May be taken with food to reduce GI upset, but absorption is optimal on an empty stomach. Avoid alcohol as it may exacerbate hepatic side effects. |
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| Lactation Rating | L2 (Probably Compatible) |
| 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. |
| 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. |
| Clinical Pearls | PEDIAMYCIN 400 (erythromycin ethylsuccinate) is a macrolide antibiotic; use with caution in hepatic impairment and in patients with QT prolongation. It inhibits CYP3A4, leading to increased levels of statins, warfarin, and benzodiazepines. Administer on an empty stomach for optimal absorption, but can be taken with food if GI upset occurs. |
| Patient Advice | Take this medication exactly as prescribed, even if you feel better. · Complete the full course of therapy to prevent resistance. · Do not take with grapefruit juice as it may increase side effects. · Common side effects include nausea, vomiting, abdominal pain, and diarrhea. · Avoid alcohol while taking this medication. · Notify your doctor if you experience severe diarrhea, rash, or signs of liver problems (yellowing of skin/eyes, dark urine). · This medicine may interact with many drugs, so inform your doctor of all medications you take. |