Is Fleet Phosphosoda Safe?

Patient Expert

I have chronic ulcerative colitis and undergo yearly colonoscopy. I previously have taken a fleet phosphosoda prep. I have heard that this might not be safe. What are my options?

As most people who undergo colonoscopy will attest to, the worst part of the procedure is the preparation. When colonoscopy was first developed, the standard prep was a one gallon solution, Golytely. A one gallon jug with powder is filled with water and mixed. One glass is drunk every 15 minutes over a four hour period until the gallon is completed.

If after drinking the gallon your stool is not a clear liquid, Dulcolax tablets or a Fleet enema can be taken to complete the prep. Given the large volume, this was a difficult prep to take, but since the Golytely essentially goes in one end and comes out the other without absorption, electrolytes are not affected and it was safe. Fleet Phospho-Soda, a lower volume prep was developed a few years later. In this prep, 3 ounces of Fleet Phospho-Soda is mixed with a glass of either eater or ginger ale and taken in a split dose six hours apart. While this is a much easier prep to do, there were some known dangers.

Unlike Golytely, which works via volume, the small volume Fleet's Phospho-Soda works by pulling fluid into the colon, and can have significant effects on body fluids. Since its development, it was warned that Fleet's Phospho-Soda not be used in patients with diabetes, kidney problems or congestive heart failure. About a year ago, there were preliminary reports that a small group of patients without diabetes, kidney problems or heart failure developed kidney failure requiring dialysis after taking a Fleet Phospho-Soda prep. While most physicians stopped using the Fleet Phospho-Soda prep at that time, some continued to use it in low-risk patients. They postulated that dehydration contributed to the kidney failure.

It was felt that as long as those patients drank lots of fluids, and were not taking any diuretics, it wouldn't be a problem. Just this past week, however, because of more studies showing numerous cases of kidney failure in low-risk patients, the FDA has taken Fleet Phospho-Soda off of the market. Over the years, as Golytely became unpopular due to its high volume, half-gallon products, Half-Lytely and MoviePrep were developed. Like Golytely, these products are safe and do not carry the risk of kidney disease.

Frequently patients will ask about the "pill prep". This is made up of ingesting three pills every 15 minutes with a glass of water, for a total of 24-40 pills depending on the prep. The two products were Osmo Prep and Visicol. Patients were happy with this prep, as there was no taste. However, both of these tablets are made up of Fleet Phospho-Soda, and carried the increased risk of kidney failure. As noted above, these have also been recently taken off of the market.

Recently, Physicians are working hard to come up with preps that are both palatable and safe. In addition to Golytely, Half-Lytely and MoviePrep, some are using combinations of citrate of Magnesia, Miralax and Gatorade with Dulcolax tablets. Some patients require a 2 day preparation. You should check with your gastroenterologist and see what is recommended for you.