PEDIAMYCIN

Clinical safety rating: caution

Comprehensive clinical and safety monograph for PEDIAMYCIN (PEDIAMYCIN).

How it works

Erythromycin is a macrolide antibiotic that binds to the 50S subunit of the bacterial ribosome, inhibiting protein synthesis by blocking translocation of peptidyl-tRNA. It may be bacteriostatic or bactericidal depending on concentration and organism.

What the body does with it

Metabolism	Primarily hepatic via demethylation; CYP3A4 is the major enzyme involved. Also metabolized by CYP2C9, CYP2C19. Elimination half-life ~1.5-2 hours (increased in hepatic impairment).
Excretion	PEDIAMYCIN (erythromycin ethylsuccinate) is primarily excreted via the biliary route (60-70% as unchanged drug and metabolites) with significant fecal elimination. Renal excretion accounts for only 5-15% of the dose, mostly as inactive metabolites. Less than 5% is excreted unchanged in urine.
Half-life	The terminal elimination half-life is approximately 1.5-2 hours in adults with normal renal function. In patients with severe hepatic impairment, half-life may be prolonged to 5-6 hours. The short half-life necessitates frequent dosing (every 6-8 hours) to maintain therapeutic levels.
Protein binding	Erythromycin is 70-90% bound to plasma proteins, primarily to alpha-1-acid glycoprotein (AAG) and albumin. Binding is saturable and concentration-dependent.
Volume of Distribution	The apparent volume of distribution is 0.6-0.9 L/kg, indicating distribution into total body water and some tissue binding. Higher Vd in neonates (0.8-1.2 L/kg) due to increased extracellular fluid.
Bioavailability	Oral bioavailability of erythromycin ethylsuccinate is 30-65% (mean 45%), reduced by food. Intramuscular bioavailability is approximately 70-80% due to erratic absorption. Intravenous administration yields 100% bioavailability.
Onset of Action	Oral: Onset of action occurs within 1-2 hours after a dose, with peak serum concentrations reached 0.5-2.5 hours. Intravenous: Onset is rapid, within minutes, with peak concentrations at the end of infusion.
Duration of Action	Duration of action is approximately 6-8 hours after oral administration, supporting a dosing interval of every 6-8 hours. For intravenous therapy, duration is similar due to rapid clearance.

Classification & Brands

Dosing & administration

250-500 mg orally every 6 hours; maximum 2 g/day.

Dosage form	GRANULE
Renal impairment	GFR >50 mL/min: no adjustment; GFR 10-50 mL/min: 250 mg every 6-8 hours; GFR <10 mL/min: 250 mg every 12-24 hours.
Liver impairment	Child-Pugh A: cautious use; Child-Pugh B or C: contraindicated.
Pediatric use	Children: 30-50 mg/kg/day orally divided every 6 hours.
Geriatric use	Use lowest effective dose; monitor renal function; adjust based on creatinine clearance.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for PEDIAMYCIN (PEDIAMYCIN).

Breastfeeding	Erythromycin is excreted into breast milk in small amounts. The milk-to-plasma (M/P) ratio is approximately 0.5. Breastfeeding is generally considered compatible, but caution is advised in infants with hepatic or biliary disease as erythromycin may accumulate. Monitor for gastrointestinal disturbances and potential risk of pyloric stenosis in young infants.
Teratogenic Risk	PEDIAMYCIN (erythromycin) is generally considered low risk in pregnancy. No increased risk of major malformations has been consistently demonstrated in first trimester exposure. However, there is a possible association with pyloric stenosis in infants exposed in utero, though this risk remains small. Fetal monitoring is recommended in advanced pregnancy due to rare reports of fetal distress.

Warnings & precautions

■ FDA Black Box Warning

Erythromycin has been associated with QT prolongation and rare cases of torsades de pointes. Caution in patients with electrolyte abnormalities, bradycardia, or concomitant use of other QT-prolonging drugs. Also, erythromycin estolate is associated with hepatotoxicity; use with caution in hepatic impairment.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to erythromycin or any macrolide antibiotic","Pre-existing QT prolongation or history of torsades de pointes","Concomitant use with ergotamine or dihydroergotamine","Significant hepatic impairment (especially with estolate salt)"]

Clinical Precautions

Precautions

["QT prolongation and cardiac arrhythmias (especially with intravenous use or in patients with risk factors)","Hepatic dysfunction (especially with erythromycin estolate)","Exacerbation of myasthenia gravis","Clostridium difficile-associated diarrhea","Ototoxicity (especially with high doses or renal impairment)","Drug interactions (CYP3A4 inhibitors/inducers, statins, warfarin, digoxin)"]

Clinical Tips & Counseling

Drug interactions

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PEDIAMYCIN

Clinical safety rating: caution

Comprehensive clinical and safety monograph for PEDIAMYCIN (PEDIAMYCIN).

How it works

What the body does with it

Metabolism	Primarily hepatic via demethylation; CYP3A4 is the major enzyme involved. Also metabolized by CYP2C9, CYP2C19. Elimination half-life ~1.5-2 hours (increased in hepatic impairment).
Excretion	PEDIAMYCIN (erythromycin ethylsuccinate) is primarily excreted via the biliary route (60-70% as unchanged drug and metabolites) with significant fecal elimination. Renal excretion accounts for only 5-15% of the dose, mostly as inactive metabolites. Less than 5% is excreted unchanged in urine.
Half-life	The terminal elimination half-life is approximately 1.5-2 hours in adults with normal renal function. In patients with severe hepatic impairment, half-life may be prolonged to 5-6 hours. The short half-life necessitates frequent dosing (every 6-8 hours) to maintain therapeutic levels.
Protein binding	Erythromycin is 70-90% bound to plasma proteins, primarily to alpha-1-acid glycoprotein (AAG) and albumin. Binding is saturable and concentration-dependent.
Volume of Distribution	The apparent volume of distribution is 0.6-0.9 L/kg, indicating distribution into total body water and some tissue binding. Higher Vd in neonates (0.8-1.2 L/kg) due to increased extracellular fluid.
Bioavailability	Oral bioavailability of erythromycin ethylsuccinate is 30-65% (mean 45%), reduced by food. Intramuscular bioavailability is approximately 70-80% due to erratic absorption. Intravenous administration yields 100% bioavailability.
Onset of Action	Oral: Onset of action occurs within 1-2 hours after a dose, with peak serum concentrations reached 0.5-2.5 hours. Intravenous: Onset is rapid, within minutes, with peak concentrations at the end of infusion.
Duration of Action	Duration of action is approximately 6-8 hours after oral administration, supporting a dosing interval of every 6-8 hours. For intravenous therapy, duration is similar due to rapid clearance.

Classification & Brands

Dosing & administration

250-500 mg orally every 6 hours; maximum 2 g/day.

Dosage form	GRANULE
Renal impairment	GFR >50 mL/min: no adjustment; GFR 10-50 mL/min: 250 mg every 6-8 hours; GFR <10 mL/min: 250 mg every 12-24 hours.
Liver impairment	Child-Pugh A: cautious use; Child-Pugh B or C: contraindicated.
Pediatric use	Children: 30-50 mg/kg/day orally divided every 6 hours.
Geriatric use	Use lowest effective dose; monitor renal function; adjust based on creatinine clearance.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for PEDIAMYCIN (PEDIAMYCIN).

Breastfeeding	Erythromycin is excreted into breast milk in small amounts. The milk-to-plasma (M/P) ratio is approximately 0.5. Breastfeeding is generally considered compatible, but caution is advised in infants with hepatic or biliary disease as erythromycin may accumulate. Monitor for gastrointestinal disturbances and potential risk of pyloric stenosis in young infants.
Teratogenic Risk	PEDIAMYCIN (erythromycin) is generally considered low risk in pregnancy. No increased risk of major malformations has been consistently demonstrated in first trimester exposure. However, there is a possible association with pyloric stenosis in infants exposed in utero, though this risk remains small. Fetal monitoring is recommended in advanced pregnancy due to rare reports of fetal distress.