Excipient (pharmacologically inactive substance)
What is it?
Potassium carbonate, K2CO3, appears as a white powder or as colorless solid crystal and has a salty taste. Also known as potash or pearl ash, it may be used in pharmaceutical laboratories as a drying agent or as a source of potassium. It also used in fire extinguishers, to make soap, to make glass, and to soften water. It is also found in effervescent tablets. Effervescent tablets and powders are available to provide potassium when there are low levels of potassium in the blood due to inadequate diet, nausea and vomiting, diarrhea or use of certain medications such as corticosteroids or diuretics. They dissolve quickly, are stable, convenient and easy to carry.
All carbonate salts are on the FDA generally regarded as safe list. There is no evidence in the available information on calcium carbonate, potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, or sodium sesquicarbonate that demonstrates or suggests reasonable grounds to suspect a hazard to the public when used at normal levels that are now current or that might reasonably be expected in the future.
 FDA - CFR Code of Federal Regulation Title 21. Part 331. Antacid Products for over-the-counter (OTC) human use. Subpart B. Active ingredients. Sec. 331.11 Listing of specific active ingredients. Updated April 1, 2012. Accessed August 22, 2012. http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfCFR/CFRSearch.cfm?fr=331.11