E.E.S. 200
Clinical safety rating: caution
Comprehensive clinical and safety monograph for E.E.S. 200 (E.E.S. 200).
Erythromycin acts by binding to the 50S ribosomal subunit of susceptible bacteria, inhibiting protein synthesis by blocking translocation of peptidyl-tRNA. It may also inhibit ribosomal assembly.
| Metabolism | Metabolized primarily via hepatic CYP3A4 and is a moderate inhibitor of CYP3A4. Eliminated mainly in bile, with some renal excretion. |
| Excretion | Primarily hepatic metabolism and biliary excretion; approximately 5-15% of active drug excreted renally, with fecal elimination accounting for the majority of the remaining dose. |
| Half-life | Approximately 1.5-2 hours in adults with normal renal function; may be prolonged to 5-6 hours in severe renal impairment. |
| Protein binding | 70-80% bound primarily to alpha-1-acid glycoprotein (AAG) and to a lesser extent albumin. |
| Volume of Distribution | 0.5-0.9 L/kg; extensive tissue penetration (except CSF and brain unless meninges inflamed). |
| Bioavailability | Oral: 25-50% (base); variable due to acid instability; enteric-coated formulations improve absorption. |
| Onset of Action | Oral: 1-2 hours (time to peak serum concentration); peak antibacterial effect correlates with serum levels. |
| Duration of Action | 6-12 hours (bacteriostatic effect persists while drug levels remain above MIC); clinical dosing every 6-12 hours. |
400 mg orally every 6 hours as the ethylsuccinate salt. Maximum daily dose 4 g.
| Dosage form | SUSPENSION |
| Renal impairment | No dose adjustment required for GFR >10 mL/min. For GFR <10 mL/min, reduce dose by 25-50% or administer at prolonged intervals. |
| Liver impairment | Child-Pugh A: No adjustment. Child-Pugh B: Reduce dose by 50%. Child-Pugh C: Reduce dose by 75% or avoid use. |
| Pediatric use | 30-50 mg/kg/day orally in divided doses every 6 hours, as ethylsuccinate. Maximum 2 g/day. |
| Geriatric use | No specific dose adjustment, but monitor for ototoxicity and QT prolongation. Initiate at lower end of dosing range. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for E.E.S. 200 (E.E.S. 200).
| Breastfeeding | Erythromycin is excreted into breast milk in small amounts. The milk-to-plasma ratio (M/P) is approximately 0.5. Oral absorption by the infant is minimal, and adverse effects are rare. However, there is a theoretical risk of infant gastrointestinal disturbance or allergic reaction. The American Academy of Pediatrics considers erythromycin compatible with breastfeeding. Caution is advised, especially in infants with jaundice or hepatic impairment. |
| Teratogenic Risk | Erythromycin (E.E.S. 200) is classified as FDA Pregnancy Category B. Animal reproduction studies have not demonstrated fetal risk, but no adequate human studies exist. First trimester: No teratogenic effects reported; however, use only if clearly needed. Second and third trimesters: Considered safe; no known fetal toxicity. There is a potential association with pyloric stenosis in neonates if used after 32 weeks gestation, though absolute risk is low. Overall risk-benefit assessment should consider maternal infection treatment necessity. |
■ FDA Black Box Warning
Increased risk of infantile hypertrophic pyloric stenosis (IHPS) when used in neonates; use only when no alternative therapy is available.
| Serious Effects |
Hypersensitivity to erythromycin or any macrolide antibiotic; concomitant use with CYP3A4 substrates that prolong QT interval (e.g., cisapride, pimozide, ergotamine) due to risk of arrhythmias.
| Precautions | Potential for QT prolongation and torsades de pointes, especially in patients with electrolyte disturbances or concurrent use of other QT-prolonging drugs; hepatic impairment; myasthenia gravis worsening; superinfection; risk of IHPS in neonates; caution in renal impairment. |
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| Fetal Monitoring | Maternal monitoring should include liver function tests (erythromycin can cause hepatotoxicity), auditory function (especially with high doses or renal impairment), and ECG for QT prolongation risk. Fetal monitoring includes ultrasound for growth and development if used in first trimester. Neonatal monitoring should include observation for symptoms of pyloric stenosis (projectile vomiting) if maternal use in late pregnancy. |
| Fertility Effects | No clinically significant effects on fertility have been reported in animal or human studies. Erythromycin does not affect reproductive hormones or gamete function at therapeutic doses. However, untreated infections can impair fertility, so appropriate treatment is beneficial. |