[Code of Federal Regulations]
[Title 21, Volume 5]
[Revised as of April 1, 2001]
From the U.S. Government Printing Office via GPO Access
[CITE: 21CFR331.20]

[Page 220-221]
 
                        TITLE 21--FOOD AND DRUGS
 
CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN 
                           SERVICES--Continued
 
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

[[Page 221]]

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 30030 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 Ingredient x100)/
(Total mEq. Antacid Product).

[61 FR 4823, Feb. 8, 1996]