Name: Erythromycin Stearate USP

T.S.No.: SPEC/API/HES-005/D/01
Issue Date: 01/03/2006

Code: HES

CAS: 643-22-1

Storage: Preserve in tight containers.

Supersede: SPEC/API/HES-005/D
Date: 01/04/2002

M.F.:  C37 H67 NO13. C18 H36 O2

M.W.: 1018.40g/mole







White or slightly yellow crystals or powder. It should odourless or may have a slight, earthy odor, and has a slight bitter taste.



Practically insoluble in water; soluble in alcohol, in chloroform, in methanol, and in ether.

Identification      (By IR)


The IR absorption spectrum of the sample should exhibit maxima only at the same wavelengths as that of a similarly preparation of working standard of Erythromycin stearate.



Meets the requirements

Water Content


Not more than 4.00%w/w.

Residue on Ignition


Not More Than 1.000%w/w.

Related compounds


Pseudoerythromycin A enol ether should not be more than 3.00%w/w,
Erythromycin A enol ether should not be more than 3.00%w/w, and

Any  individual related compound should not be more than 3.00%w/w.

Residual Solvents


Acetone: Not more than 5000.00ppm.

Methylene chloride: Not more than 600.00ppm.



The sum of the percentages of Erythromycin A, Erythromycin B and Erythromycin C should not be less than 55.00%w/w , calculated on anhydrous basis.

End of specification