Correspondence

Declaring the Sodium Content of Drug Products

N Engl J Med 1995; 333:1291November 9, 1995

Article

To the Editor:

Those who prescribe medications may be unaware that they may contain substantial amounts of sodium. References such as package inserts, the Physicians' Desk Reference, and Drug Information 1 do not always provide information about sodium, and the sodium content, when it does appear, may be given in various units of measurement or may need to be calculated.

Certain medications containing one or more drugs are high in sodium content regardless of the formulation used, whereas others vary according to the formulation (Table 1Table 1Sodium Content of Various Drug Products and Formulations.). High-sodium and low-sodium formulations of the same drug products should not be used interchangeably in patients who are following sodium-restricted diets.

The Food and Drug Administration (FDA) has proposed a rule for the labeling of the sodium content of over-the-counter drugs,4 and it will be working with pharmaceutical organizations to develop voluntary sodium labeling for prescription drugs. The FDA will recommend that makers of prescription drugs declare the sodium content if it exceeds 5 mg (0.22 mmol) per single recommended dose and that they issue a warning if the sodium content exceeds 140 mg (6.09 mmol) per maximal daily dose. Sodium contained in active ingredients, excipients, and any recommended diluent will be included. These measures will simplify the calculation of the total sodium content of any product prescribed for patients whose sodium intake is restricted. Until these initiatives have been implemented, this information should be obtained from the manufacturer.

Any serious adverse event thought to be associated with drug use should be reported to the FDA's MedWatch Program (telephone, 1-800-FDA-1088).

Ana Szarfman, M.D., Ph.D.
Thomas Kuchenberg
Janice Soreth, M.D.
Food and Drug Administration, Rockville, MD 20857

Simon Lajmanovich, Ph.D.
4700 Bradley Blvd., Chevy Chase, MD 20815

4 References

1. 1

   American Hospital Formulary Service (AHFS) drug information 94. Bethesda, Md.: American Society of Hospital Pharmacists, 1994.
   

2. 2

   Center for Drug Evaluation and Research. Approved drug products with therapeutic equivalence evaluations. 15th ed. Washington, D.C.: Government Printing Office, 1995.
   

3. 3

   The Merck index. Rahway, N.J.: Merck, 1989.
   

4. 4

   Drug labeling: sodium labeling for over-the-counter drugs: proposed amendmentFed Regist 1991;56:1922-1922