ERYZOLE

Clinical safety rating: caution

Comprehensive clinical and safety monograph for ERYZOLE (ERYZOLE).

How it works

Erythromycin acts by binding to the 50S subunit of the bacterial ribosome, inhibiting protein synthesis by blocking the translocation step.

What the body does with it

Metabolism	Primarily metabolized by hepatic CYP3A4 enzyme; forms an inactive demethylated metabolite and other active metabolites.
Excretion	Renal excretion of unchanged drug accounts for approximately 75% of the dose; fecal elimination is about 20%, with the remainder as biliary metabolites.
Half-life	Terminal elimination half-life is 4-6 hours in patients with normal renal function (creatinine clearance >60 mL/min). In severe renal impairment (CrCl <30 mL/min), half-life may extend to 12-18 hours.
Protein binding	Approximately 92-95% bound to albumin; binding is concentration-independent.
Volume of Distribution	0.8-1.2 L/kg, indicating extensive distribution into total body water and tissues (e.g., skin, lung, liver).
Bioavailability	Oral: 65-75% (first-pass metabolism reduces bioavailability); Intravenous: 100%; Topical: <5% systemic absorption.
Onset of Action	Oral: 30-60 minutes; Intravenous: 5-15 minutes; Topical: 24-48 hours for clinical effect.
Duration of Action	Oral/IV: 8-12 hours; Topical: 12-24 hours after application. Duration is prolonged in renal impairment.

Classification & Brands

Dosing & administration

Adults: 500 mg orally once daily for 3 consecutive days per month.

Dosage form	GRANULE
Renal impairment	GFR 30-50 mL/min: No adjustment needed. GFR 10-29 mL/min: 250 mg once daily for 3 consecutive days per month. GFR <10 mL/min or dialysis: Not recommended.
Liver impairment	Child-Pugh A and B: No adjustment needed. Child-Pugh C: Use with caution, reduce dose by 50% (250 mg once daily for 3 consecutive days per month).
Pediatric use	Children (≥6 years, weight ≥15 kg): 30 mg/kg (max 500 mg) orally once daily for 3 consecutive days per month. For children <6 years or weight <15 kg, safety not established.
Geriatric use	No specific dose adjustment, but monitor renal function closely; consider dose reduction if GFR <30 mL/min.

Use during pregnancy

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

Clinical note

Comprehensive clinical and safety monograph for ERYZOLE (ERYZOLE).

Breastfeeding

Excreted into breast milk; M/P ratio approximately 0.5. The American Academy of Pediatrics considers erythromycin compatible with breastfeeding, except the estolate salt has been associated with infant pyloric stenosis. Caution is advised; monitor infant for gastrointestinal symptoms and jaundice.

Teratogenic Risk

Pregnancy Category X. Erythromycin estolate (the form in ERYZOLE) is contraindicated because it is associated with an increased risk of cardiovascular malformations, pyloric stenosis, and other fetal anomalies when used during pregnancy, particularly in the first trimester. Animal studies have demonstrated teratogenicity. The risk of major congenital malformations is highest with first-trimester exposure.

Warnings & precautions

■ FDA Black Box Warning

Increased risk of cardiac death associated with erythromycin, especially when co-administered with strong CYP3A4 inhibitors such as verapamil, diltiazem, and certain antifungal agents.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to erythromycin or any component of the formulation","Concurrent use with ergotamine or dihydroergotamine (ergot toxicity)","Concurrent use with strong CYP3A4 inhibitors (e.g., verapamil, diltiazem, ketoconazole, itraconazole) due to risk of cardiac death","Hepatic impairment (relative contraindication for some formulations)","Preexisting QT prolongation or history of arrhythmia"]

Clinical Precautions

Precautions

["QT prolongation and torsades de pointes; avoid in patients with prolonged QTc interval, electrolyte disturbances, or concurrent use of other QT-prolonging drugs","Hepatic dysfunction, cholestatic hepatitis","Infantile hypertrophic pyloric stenosis (IHPS) in neonates","Exacerbation of myasthenia gravis","Allergic reactions, including Stevens-Johnson syndrome","Overgrowth of nonsusceptible organisms with prolonged use","Hearing loss with high doses, especially in renal impairment"]

Clinical Tips & Counseling

Drug interactions

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ERYZOLE

Clinical safety rating: caution

Comprehensive clinical and safety monograph for ERYZOLE (ERYZOLE).

How it works

Erythromycin acts by binding to the 50S subunit of the bacterial ribosome, inhibiting protein synthesis by blocking the translocation step.

What the body does with it

Metabolism	Primarily metabolized by hepatic CYP3A4 enzyme; forms an inactive demethylated metabolite and other active metabolites.
Excretion	Renal excretion of unchanged drug accounts for approximately 75% of the dose; fecal elimination is about 20%, with the remainder as biliary metabolites.
Half-life	Terminal elimination half-life is 4-6 hours in patients with normal renal function (creatinine clearance >60 mL/min). In severe renal impairment (CrCl <30 mL/min), half-life may extend to 12-18 hours.
Protein binding	Approximately 92-95% bound to albumin; binding is concentration-independent.
Volume of Distribution	0.8-1.2 L/kg, indicating extensive distribution into total body water and tissues (e.g., skin, lung, liver).
Bioavailability	Oral: 65-75% (first-pass metabolism reduces bioavailability); Intravenous: 100%; Topical: <5% systemic absorption.
Onset of Action	Oral: 30-60 minutes; Intravenous: 5-15 minutes; Topical: 24-48 hours for clinical effect.
Duration of Action	Oral/IV: 8-12 hours; Topical: 12-24 hours after application. Duration is prolonged in renal impairment.

Classification & Brands

Dosing & administration

Adults: 500 mg orally once daily for 3 consecutive days per month.

Dosage form	GRANULE
Renal impairment	GFR 30-50 mL/min: No adjustment needed. GFR 10-29 mL/min: 250 mg once daily for 3 consecutive days per month. GFR <10 mL/min or dialysis: Not recommended.
Liver impairment	Child-Pugh A and B: No adjustment needed. Child-Pugh C: Use with caution, reduce dose by 50% (250 mg once daily for 3 consecutive days per month).
Pediatric use	Children (≥6 years, weight ≥15 kg): 30 mg/kg (max 500 mg) orally once daily for 3 consecutive days per month. For children <6 years or weight <15 kg, safety not established.
Geriatric use	No specific dose adjustment, but monitor renal function closely; consider dose reduction if GFR <30 mL/min.

Use during pregnancy

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

Clinical note

Comprehensive clinical and safety monograph for ERYZOLE (ERYZOLE).

Breastfeeding

Teratogenic Risk

Warnings & precautions

■ FDA Black Box Warning

Increased risk of cardiac death associated with erythromycin, especially when co-administered with strong CYP3A4 inhibitors such as verapamil, diltiazem, and certain antifungal agents.