ILOTYCIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ILOTYCIN (ILOTYCIN).
Erythromycin binds to the 50S subunit of bacterial ribosomes, inhibiting protein synthesis by blocking peptidyl transferase activity and preventing translocation of peptides.
| 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. |
| Molecular Weight | 733.93 |
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. |
| 1st trimester | Crosses placenta; no evidence of harm in animal studies; use only if clearly needed. |
| 2nd trimester | Generally considered safe; no known teratogenicity. |
| 3rd trimester | Use near term may increase risk of infantile hypertrophic pyloric stenosis (IHPS); avoid if possible. |
Clinical note
Comprehensive clinical and safety monograph for ILOTYCIN (ILOTYCIN).
| Placental transfer | Crosses placenta; achieves fetal serum levels about 2-20% of maternal serum levels. |
| Breastfeeding | Excreted into breast milk in low amounts; considered compatible with breastfeeding; monitor infant for gastrointestinal effects. |
| Lactation Rating |
■ 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.
| Serious Effects |
Hypersensitivity to erythromycin or any macrolide antibioticConcomitant use with ergotamine or dihydroergotamineConcomitant use with cisapride, pimozide, terfenadine, astemizole (risk of QT prolongation)
| 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 |
| Food/Dietary | Take erythromycin on an empty stomach with a full glass of water, at least 1 hour before or 2 hours after meals. Avoid grapefruit and grapefruit juice during therapy due to increased drug absorption and risk of QT prolongation. Alcohol may worsen GI side effects but no specific interaction; limit use. |
Loading safety data…
| L2 (Safer) |
| 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. |
| Fetal Monitoring | No specific monitoring required beyond routine prenatal care. Monitor maternal liver function if prolonged therapy. |
| Fertility Effects | No adverse effects on fertility reported in animal or human studies. |
| Clinical Pearls | Erythromycin (Ilotycin) is a macrolide antibiotic that also acts as a motilin receptor agonist, making it useful for gastroparesis. It is a strong CYP3A4 inhibitor; avoid coadministration with statins, warfarin, and other CYP3A4 substrates. QT prolongation risk increases with concomitant use of other QT-prolonging drugs or in patients with electrolyte abnormalities. Intravenous administration can cause phlebitis; dilute appropriately and consider central line for prolonged therapy. Erythromycin is pregnancy category B and is preferred over doxycycline for syphilis in pregnant patients. Use with caution in myasthenia gravis due to risk of exacerbation. |
| Patient Advice | Take erythromycin on an empty stomach (1 hour before or 2 hours after meals) for best absorption unless directed otherwise. · You may experience gastrointestinal side effects such as nausea, vomiting, abdominal cramps, or diarrhea; these are common and often improve with continued therapy. · Inform your doctor if you develop severe or watery diarrhea, especially if it contains blood or mucus, as this may indicate Clostridium difficile infection. · Erythromycin can cause hearing loss, especially at high doses or with renal impairment; report any ringing in the ears or changes in hearing. · Avoid consuming grapefruit or grapefruit juice while taking erythromycin, as it can increase the risk of serious side effects. · Contact your doctor immediately if you experience chest pain, palpitations, or fainting spells, as erythromycin can affect heart rhythm. · Complete the full course of therapy even if you feel better; stopping early may lead to bacterial resistance. · Erythromycin may reduce the effectiveness of oral contraceptives; use an additional method of birth control during treatment. |