The U.S. Food and Drug Administration's (FDA) guidelines for over-the-counter drug labels help protect people with kidney disease or other chronic conditions. More than 20 million Americans suffer from some form of chronic kidney disease. Another 20 million people, most of whom have diabetes, are at risk.
People with kidney disease have a decreased ability to excrete water, electrolytes and waste materials. As a result, most have to carefully watch their diet and limit the amount of certain foods. Sodium, magnesium and potassium are some of the more important electrolytes that people with certain diseases need to be concerned about. Limiting sodium is important for people with reduced kidney function, congestive heart failure and high blood pressure. Magnesium and potassium levels tend to rise as kidney function deteriorates. High blood levels of sodium, magnesium and potassium can cause symptoms. Very high levels can cause serious problems. For people with normal kidneys, excreting these electrolytes is rarely a problem.
Under current FDA rules, the label for over-the-counter drugs that contain these ingredients includes a specific listing of the amounts. There's a warning on the label if the amount of sodium, potassium, or magnesium is greater than a specified amount. The warning will alert people with a history of kidney stones, certain kinds of kidney disease or other diseases who require a limit on their daily intake.
The calcium content of nonprescription drugs is also listed. Blood calcium levels in kidney disease tend to be low. But other chronic conditions can lead to high blood calcium levels, especially when too much extra calcium and vitamin D are ingested. Like the other electrolytes, a warning appears if the amount of calcium exceeds a safe dose.
Today's over-the-counter drug labels impact product advertising. Many over-the-counter drug products previously labeled “sodium free” really weren’t. Those that did contain small amounts of sodium that were low enough to meet the FDA standards continued to be labeled as sodium-free. Those products that exceed the allowed sodium amount were forced to remove "sodium-free" from the label. The rule allows a product to be listed as sodium-free if it contains less than 5 milligrams of sodium in a single maximum dose or 140 milligrams in a maximum daily dose.
The warnings about sodium, calcium, potassium and magnesium content will be on a section of the label called “Other information.”
Here is an example of the current over-the-counter label format:
Harold J. DeMonaco, M.S. is senior clinical associate in the Decision Support and Quality Management Unit at the Massachusetts General Hospital. He is author of over 20 publications in the pharmacy and medical literature and routinely reviews manuscript submissions for medical journals.