[Code of Federal Regulations]
[Title 21, Volume 5]
[Revised as of April 1, 2008]
From the U.S. Government Printing Office via GPO Access
[CITE: 21CFR331.20]

[Page 220]
 
                        TITLE 21--FOOD AND DRUGS
 
CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF 
 
PART 331_ANTACID PRODUCTS FOR OVER-THE-COUNTER (OTC) 
HUMAN USE--Table of Contents
 
                      Subpart C_Testing Procedures
 
Sec. 331.20  Determination of percent contribution of active ingredients.


    To determine the percent contribution of an antacid active 
ingredient, place an accurately weighed amount of the antacid active 
ingredient equal to the amount present in a unit dose of the product 
into a 250-milliliter (mL) beaker. If wetting is desired, add not more 
than 5 mL of alcohol (neutralized to an apparent pH of 3.5), and mix to 
wet the sample thoroughly. Add 70 mL of water, and mix on a magnetic 
stirrer at 300 30 r.p.m. for 1 minute. Analyze the 
acid neutralizing capacity of the sample according to the procedure 
provided in the United States Pharmacopeia 23/National Formulary 18 and 
calculate the percent contribution of the antacid active ingredient in 
the total product as follows:
    Percent contribution =(Total mEq. Antacid Active Ingredientx100)/
(Total mEq. Antacid Product).

[61 FR 4823, Feb. 8, 1996]