ERYGEL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ERYGEL (ERYGEL).
Erythromycin is a macrolide antibiotic that inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit, blocking the translocation of peptidyl-tRNA.
| Metabolism | Hepatic metabolism via CYP3A4; major metabolite is demethylerythromycin. |
| Excretion | Primarily hepatic metabolism; less than 10% excreted renally as unchanged drug. Biliary excretion is minimal. |
| Half-life | Terminal elimination half-life is approximately 1.6 hours (range 1.0–2.5 hours) after topical application, too short to accumulate with daily use. |
| Protein binding | Approximately 99% bound to serum proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution not clinically relevant for topical formulation; systemic absorption is minimal (<0.1% of applied dose). |
| Bioavailability | Bioavailability after topical application is extremely low (<0.1%) due to minimal percutaneous absorption. |
| Onset of Action | Onset of clinical effect (reduction of acne lesions) is typically observed after 4–8 weeks of once-daily topical application. |
| Duration of Action | Duration of action is sustained throughout the dosing interval with once-daily application; effect persists for at least 24 hours after each dose. |
| Molecular Weight | 733.94 |
Apply a thin layer to affected areas twice daily. Topical use only.
| Dosage form | GEL |
| Renal impairment | No dose adjustment required. |
| Liver impairment | No dose adjustment required. |
| Pediatric use | Not recommended for children under 12 years; for ages 12 and older, same as adult dosing. |
| Geriatric use | No specific dose adjustment; use caution due to potential skin irritation. |
| 1st trimester | Erythromycin is generally considered safe during the first trimester; however, there is a theoretical risk of cardiovascular malformations based on some observational studies. Use only if clearly needed. |
| 2nd trimester | Erythromycin is considered safe in the second trimester. No specific risks identified; use when benefit outweighs risk. |
| 3rd trimester | Erythromycin is considered safe in the third trimester. However, there is a risk of infantile hypertrophic pyloric stenosis (IHPS) if used near term or during breastfeeding in neonates. Avoid late pregnancy unless necessary. |
Clinical note
Comprehensive clinical and safety monograph for ERYGEL (ERYGEL).
| Placental transfer | Erythromycin crosses the placenta at low to moderate levels, achieving approximately 5-20% of maternal serum concentration in fetal blood. The protein binding of erythromycin is about 70-80%, which limits placental transfer. However, transfer occurs via passive diffusion. |
| Breastfeeding |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to erythromycin or any macrolide antibioticConcomitant use with ergotamine or dihydroergotamine (risk of ergotism)Concomitant use with cisapride or pimozide (risk of QT prolongation and cardiac arrhythmias)History of cholestatic jaundice or hepatic impairment associated with prior erythromycin use
| Precautions | Potential for QT prolongation and risk of cardiac arrhythmias, especially with concomitant use of other QT-prolonging drugs., Risk of antibiotic-associated colitis (pseudomembranous colitis) due to Clostridium difficile., Hepatic impairment may require dose adjustment. |
| Food/Dietary | No known food interactions with topical ERYGEL. Avoid consuming alcohol or spicy foods if they exacerbate acne. No dietary restrictions required for efficacy. |
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| Erythromycin is excreted into breast milk in small amounts. The risk of infantile hypertrophic pyloric stenosis (IHPS) in infants under 2 months of age is a concern, especially with maternal oral or topical use near delivery. Topical application (e.g., ERYGEL) has minimal systemic absorption and is generally considered compatible with breastfeeding, but caution is advised in nursing mothers of very young infants. Monitor the infant for signs of gastrointestinal disturbance, rash, or jaundice. |
| Lactation Rating | L2 (Safer) |
| Teratogenic Risk | Erythromycin (topical) is classified as FDA Pregnancy Category B. Systemic absorption is minimal; thus, no fetal risks have been documented. No known teratogenicity in first trimester. Second and third trimesters: no adverse fetal effects reported. |
| Fetal Monitoring | No specific monitoring required beyond routine prenatal care. If used for acne, assess skin irritation at application site. |
| Fertility Effects | No known adverse effects on fertility. No human studies available; animal studies show no impairment of fertility. |
| Clinical Pearls | ERYGEL (erythromycin 2% gel) is a topical macrolide antibiotic used primarily for acne vulgaris. It is bacteriostatic, inhibiting bacterial protein synthesis. Apply a thin film once or twice daily to affected areas after cleansing. Avoid contact with eyes, mouth, and mucous membranes. May cause transient stinging or burning upon application. Erythromycin resistance is common; consider combination therapy with benzoyl peroxide or retinoids to prevent resistance. Protect treated areas from excessive sunlight or UV light. Inactive ingredients may cause allergic reactions. |
| Patient Advice | Apply a thin layer of gel to the affected areas only, once or twice daily as directed. · Wash your face with a mild cleanser and pat dry before application. · Avoid contact with eyes, mouth, nose, and broken skin. · A slight burning, stinging, or tingling sensation may occur after application but usually subsides. · Do not use more or less often than prescribed; consistent use is key. · Protect treated areas from sun exposure; use sunscreen and wear protective clothing. · Inform your doctor if you have a history of allergic reactions to erythromycin or any similar medications. · If severe irritation or allergic reaction (rash, itching, swelling) occurs, discontinue use and consult your doctor. · Do not share this medication with others; it is prescribed for your specific condition. · Keep the tube tightly closed and store at room temperature away from heat and moisture. |