ILOTYCIN

Clinical safety rating: caution

Comprehensive clinical and safety monograph for ILOTYCIN (ILOTYCIN).

How it works

Erythromycin binds to the 50S subunit of bacterial ribosomes, inhibiting protein synthesis by blocking peptidyl transferase activity and preventing translocation of peptides.

What the body does with it

Metabolism	Partially metabolized in the liver via demethylation by CYP3A4. Erythromycin is a moderate inhibitor of CYP3A4.
Excretion	Approximately 80-90% renal excretion as unchanged drug via glomerular filtration and tubular secretion; 10-15% biliary/fecal elimination.
Half-life	Terminal elimination half-life is 1.5-2 hours in adults, prolonged to 4-6 hours in severe renal impairment (CrCl <10 mL/min), requiring dose adjustment.
Protein binding	Approximately 70-80% bound to albumin; 10-20% bound to α1-acid glycoprotein.
Volume of Distribution	0.5-0.8 L/kg; distributes widely into tissues but does not cross blood-brain barrier (CSF levels <10% of serum).
Bioavailability	Oral: 35-45% (due to acid lability); IV: 100%; Topical: minimal systemic absorption (<2%).
Onset of Action	Oral: 1-2 hours; IV: immediate; Topical: 2-3 hours for anti-inflammatory effect.
Duration of Action	Oral/IV: 6-8 hours (bacteriostatic levels); Topical: 12 hours.

Classification & Brands

Dosing & administration

Erythromycin base (Ilotycin): 250 mg orally every 6 hours or 500 mg every 12 hours; maximum 4 g/day. For IV: 15-20 mg/kg/day continuous infusion or divided every 6 hours.

Dosage form	OINTMENT
Renal impairment	No dose adjustment required for mild to moderate renal impairment. For severe renal impairment (CrCl <10 mL/min), reduce dose by 50% or extend interval to every 12-24 hours.
Liver impairment	Child-Pugh Class A: no adjustment. Class B: reduce dose by 50%. Class C: contraindicated or reduce dose by 75% with close monitoring.
Pediatric use	Oral: 30-50 mg/kg/day divided every 6-8 hours; maximum 2 g/day. IV: 15-20 mg/kg/day continuous infusion or divided every 6 hours; maximum 4 g/day.
Geriatric use	Increased risk of QT prolongation and ototoxicity; initiate at lower end of dosing range (250 mg orally every 6 hours) and monitor renal function, electrolytes, and ECG.

Use during pregnancy

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

Clinical note

Comprehensive clinical and safety monograph for ILOTYCIN (ILOTYCIN).

Breastfeeding	Erythromycin is excreted into breast milk with an M/P ratio of approximately 0.5. Amount is less than 10% of maternal dose; considered compatible with breastfeeding. Monitor infant for gastrointestinal effects.
Teratogenic Risk	Erythromycin (Ilotycin) is generally considered low risk during pregnancy. No evidence of teratogenicity in human studies; crosses placenta but fetal levels are low. Use caution in first trimester due to association with pyloric stenosis in infants exposed after 10 days of age, not in utero.

Warnings & precautions

■ FDA Black Box Warning

Erythromycin has been associated with prolongation of the QT interval and infrequent cases of arrhythmia. Cases of torsades de pointes have been spontaneously reported during postmarketing surveillance. Avoid concomitant use with other QT-prolonging drugs.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to erythromycin or any macrolide antibiotic","Concomitant use with ergotamine or dihydroergotamine (risk of ergot toxicity)","Concomitant use with cisapride, pimozide, or other drugs that prolong the QT interval (risk of serious arrhythmias)","Pre-existing QT prolongation or history of torsades de pointes"]

Clinical Precautions

Precautions

["QT prolongation and risk of cardiac arrhythmias, including torsades de pointes, especially in patients with risk factors (e.g., electrolyte abnormalities, bradycardia, concomitant QT-prolonging drugs)","Hepatic dysfunction including cholestatic hepatitis and jaundice","Exacerbation of myasthenia gravis","Infantile hypertrophic pyloric stenosis (IHPS) in neonates","Superinfection with prolonged use"]

Clinical Tips & Counseling

Drug interactions

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ILOTYCIN

Clinical safety rating: caution

Comprehensive clinical and safety monograph for ILOTYCIN (ILOTYCIN).

How it works

Erythromycin binds to the 50S subunit of bacterial ribosomes, inhibiting protein synthesis by blocking peptidyl transferase activity and preventing translocation of peptides.

What the body does with it

Metabolism	Partially metabolized in the liver via demethylation by CYP3A4. Erythromycin is a moderate inhibitor of CYP3A4.
Excretion	Approximately 80-90% renal excretion as unchanged drug via glomerular filtration and tubular secretion; 10-15% biliary/fecal elimination.
Half-life	Terminal elimination half-life is 1.5-2 hours in adults, prolonged to 4-6 hours in severe renal impairment (CrCl <10 mL/min), requiring dose adjustment.
Protein binding	Approximately 70-80% bound to albumin; 10-20% bound to α1-acid glycoprotein.
Volume of Distribution	0.5-0.8 L/kg; distributes widely into tissues but does not cross blood-brain barrier (CSF levels <10% of serum).
Bioavailability	Oral: 35-45% (due to acid lability); IV: 100%; Topical: minimal systemic absorption (<2%).
Onset of Action	Oral: 1-2 hours; IV: immediate; Topical: 2-3 hours for anti-inflammatory effect.
Duration of Action	Oral/IV: 6-8 hours (bacteriostatic levels); Topical: 12 hours.

Classification & Brands

Dosing & administration

Erythromycin base (Ilotycin): 250 mg orally every 6 hours or 500 mg every 12 hours; maximum 4 g/day. For IV: 15-20 mg/kg/day continuous infusion or divided every 6 hours.

Dosage form	OINTMENT
Renal impairment	No dose adjustment required for mild to moderate renal impairment. For severe renal impairment (CrCl <10 mL/min), reduce dose by 50% or extend interval to every 12-24 hours.
Liver impairment	Child-Pugh Class A: no adjustment. Class B: reduce dose by 50%. Class C: contraindicated or reduce dose by 75% with close monitoring.
Pediatric use	Oral: 30-50 mg/kg/day divided every 6-8 hours; maximum 2 g/day. IV: 15-20 mg/kg/day continuous infusion or divided every 6 hours; maximum 4 g/day.
Geriatric use	Increased risk of QT prolongation and ototoxicity; initiate at lower end of dosing range (250 mg orally every 6 hours) and monitor renal function, electrolytes, and ECG.

Use during pregnancy

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

Clinical note

Comprehensive clinical and safety monograph for ILOTYCIN (ILOTYCIN).

Breastfeeding	Erythromycin is excreted into breast milk with an M/P ratio of approximately 0.5. Amount is less than 10% of maternal dose; considered compatible with breastfeeding. Monitor infant for gastrointestinal effects.
Teratogenic Risk	Erythromycin (Ilotycin) is generally considered low risk during pregnancy. No evidence of teratogenicity in human studies; crosses placenta but fetal levels are low. Use caution in first trimester due to association with pyloric stenosis in infants exposed after 10 days of age, not in utero.