Test 1
If the product complies with this test, the labeling indicates that it meets USP 
Dissolution Test 1.
Apparatus 1:
 100 rpm.
Times:
 60 minutes, Stage 1; 60 minutes, Stage 2.
Acid stage
Using 900 mL of 
simulated gastric fluid TS (prepared without pepsin) in place of 0.1 N hydrochloric acid, conduct this stage of the test for 1 hour, and do not perform an analysis of the medium.
 
Test solution
If necessary, dilute a filtered portion of the solution under test with Dissolution Medium to obtain a solution having a concentration of about 0.28 mg of erythromycin per mL, and mix.
Procedure
Transfer a 2.0-mL portion of the 
Test solution to a suitable separator. Add 6 mL of pH 1.2 buffer (see 
Solutions in the section 
Reagents, 
Indicators, and Solutions), and 8 mL of a solution of bromocresol purple, prepared by dissolving 1 g of bromocresol purple in 1 L of pH 4.5 phosphate buffer, and mix. Extract with 40.0 mL of chloroform. Determine the amount of C
37H
67NO
13 dissolved from UV absorbances at the wavelength of maximum absorbance at about 410 nm using the chloroform extracts. Similarly prepare a Standard solution, having a known concentration of 
USP Erythromycin RS, and treat similarly.