The Food and Drug Administration (FDA) black box warning on oral sodium phosphates (OSPs) came late last year, but as early as 2003, doctors were beginning to make the link between OSP pills and solutions used to clear the bowel before colonoscopies and serious and permanent kidney injuries. As more and more reports of kidney damage and even complete kidney failure began to pour in to the FDA, the agency finally issued a mild warning in 2005. The black box warning on prescription OSP products would come three years later, after 21 more reports of serious kidney injuries. Soon after that FDA warning, C.B. Fleet quickly pulled its over-the-counter OSP products off the market.
OSP products include the prescription brands Visicol and Osmo Prep, as well as OTC brands including Fleet Phospha-soda. Over-the-counter OSP products are considered safe if used in low doses to treat constipation. But Fleet began marketing the product in higher doses as a bowel cleanser, which prompted the same risk of kidney damage and the form of kidney injury known as acute phosphate nephropathy.
OSPs work by pulling fluid from the body and out the colon, causing a laxative effect. While the body is purging itself of fluids, calcium-phosphate crystals can form in the kidneys, blocking the renal tubes. Symptoms of OSP-related kidney damage can come immediately or take as long as a few days or few weeks to surface. These symptoms include lethargy, drowsiness, decreased urine output, and swelling of the legs, ankles and feet. Often, the diagnosis isn’t immediately linked to use of OSP.
To date, more than 50 lawsuits have been filed against Fleet by people who suffered kidney injury from use of OSPs, including one recently settled in Virginia in which the lone plaintiff was awarded $10 million.