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Erythromycin Stearate

  • Chemical Name:Erythromycin stearate
  • CAS No.:643-22-1
  • MF: C55H103NO15
  • MW:1018.4
  • Specification: USP|EP|BPPurity: 98%-99% or As customer requested
  • Appearance: white to off-white
  • Solubility:ethanol: soluble50mg/mL, clear to very slightly hazy, colorless
  • Product Categories:API;Organics;Antibiotics;Macrolides;Pharmaceutical ingredients;Intermediates & Fine Chemicals;Pharmaceuticals;
  • Test method: HPLC


Erythromycin Stearate is the stearate salt form of erythromycin, a broad-spectrum, topical macrolide antibiotic with antibacterial activity. Erythromycin stearate diffuses through the bacterial cell membrane and reversibly binds to the 50S subunit of the bacterial ribosome. This prevents bacterial protein synthesis. Erythromycin stearate may be bacteriostatic or bactericidal in action, depending on the concentration of the drug at the site of infection and the susceptibility of the organism involved. (Source: NCI Thesaurus (NCIt))

Erythromycin stearate Basic information    

Product Name: Erythromycin stearate
Synonyms: qidmycin; sk-erythromycin; ERYTHROMYCIN STEARATE USP(CRM STANDARD); ErythromycinStearate-Bp/Ep/Usp; Erythromycin Stearate; Erythromycin StearateBp/Usp; Eryprim
CAS: 643-22-1
MF: C55H103NO15
MW: 1018.4
EINECS: 211-396-1
Product Categories: Pharmaceutical ingredients;Intermediates & Fine Chemicals;Pharmaceuticals; Antibiotics;Macrolides;Mechanism of Action;
Mol File: 643-22-1.mol

Gallimycin Chemical Structure

Erythromycin stearate           

Eryprim Chemical Properties   

Melting point  77-79°C
storage temp.  2-8°C
solubility  ethanol: soluble50mg/mL, clear to very slightly hazy, colorless
form  neat
color  white to off-white
Stability: Stable. Combustible. Incompatible with acids, strong oxidizing agents.
EPA Substance Registry System Erythromycin stearate (643-22-1)


Chemical Properties White Solid

Semi-synthetic macrolide antibiotic. Antibacterial
oil lubricant, plasticizer, solvent
Macrodiles antibacterial
Therapeutic Function Antibacterial
General Description

Erythromycin stearate (Ethril, Wyamycin S, Erypar) is thestearic acid salt of erythromycin. Like erythromycin base,the stearate is acid labile. It is film coated to protect it fromacid degradation in the stomach. In the alkaline pH of theduodenum, the free base is liberated from the stearateand absorbed. Erythromycin stearate is a crystalline powderthat is practically insoluble in water but soluble in alcoholand ether.
Fluffy colorless powder or fine white powder.
Air & Water Reactions Insoluble in water.
Reactivity Profile A base. Readily forms salts with acids.

MSDS: MSDS available

COA: COA can be available if you send us inquiry.

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