ERYTHRA-DERM
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ERYTHRA-DERM (ERYTHRA-DERM).
Erythromycin, a macrolide antibiotic, binds to the 50S ribosomal subunit of susceptible bacteria, inhibiting protein synthesis. It also exhibits anti-inflammatory and immunomodulatory effects, reducing neutrophil chemotaxis and bacterial lipase production.
| Metabolism | Erythromycin is primarily metabolized by the liver via cytochrome P450 isoenzyme CYP3A4, with demethylation and hydroxylation as major pathways. |
| Excretion | Primarily biliary fecal elimination (60-70%); renal excretion of unchanged drug <15%. |
| Half-life | Terminal elimination half-life of 2-4 hours; prolonged to 5-6 hours in hepatic impairment. |
| Protein binding | 70-80% bound to albumin. |
| Volume of Distribution | 0.6-0.8 L/kg; indicates extensive tissue distribution. |
| Bioavailability | Oral: 35-45% (erythromycin base); erythromycin stearate/ethylsuccinate: 25-40%. |
| Onset of Action | Topical: not applicable (local effect); oral: 1-2 hours; intravenous: immediate. |
| Duration of Action | Bacteriostatic effect persists 8-12 hours after oral dose; topical duration depends on formulation (6-8 hours). |
Apply a thin layer to the affected area(s) twice daily. For topical use only. Adult dose is 2% solution or ointment.
| Dosage form | SOLUTION |
| Renal impairment | No dosage adjustment required for topical administration. Systemic absorption is minimal. |
| Liver impairment | No dosage adjustment required for topical administration. Systemic absorption is minimal. |
| Pediatric use | Safety and efficacy in pediatric patients have not been established. Use only if potential benefit outweighs risk. |
| Geriatric use | No specific geriatric dose adjustments recommended. Use with caution due to potential for increased systemic absorption from thinned skin. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ERYTHRA-DERM (ERYTHRA-DERM).
| Breastfeeding | Topical erythromycin is minimally absorbed systemically; therefore, transfer into breast milk is negligible. M/P ratio not established for topical application. Based on oral data, erythromycin enters breast milk in low amounts (M/P ~0.5). Use during breastfeeding is considered compatible with caution for neonatal gastrointestinal effects. |
| Teratogenic Risk | Erythromycin (topical formulation ERYTHRA-DERM) has low systemic absorption; however, based on oral erythromycin data, no major teratogenic risk has been associated with use in pregnancy. There is a slight association with cardiovascular malformations in first trimester exposure from oral use, but topical use is considered minimal risk. Second and third trimester use is not associated with increased fetal risk. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to erythromycin or any macrolide antibiotic","Concurrent use with cisapride, pimozide, or ergotamine derivatives","Pre-existing QT interval prolongation or history of ventricular arrhythmias","Significant hepatic impairment"]
| Precautions | ["QT interval prolongation and risk of cardiac arrhythmias, especially torsades de pointes","Hepatotoxicity, particularly with estolate salt","Potent CYP3A4 inhibition leading to drug interactions","Increased risk of infantile hypertrophic pyloric stenosis with use in neonates","Pseudomembranous colitis due to Clostridium difficile overgrowth","Exacerbation of myasthenia gravis"] |
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| Fetal Monitoring | No specific fetal monitoring required for topical erythromycin. For maternal use, monitor for local skin reactions. If high doses or prolonged use occur, consider monitoring maternal liver function and gastrointestinal symptoms. |
| Fertility Effects | Erythromycin has no known adverse effects on fertility in animal studies or human data. Topical application is unlikely to affect reproductive function. |