Safety and colon-cleansing efficacy of a new residue-free formulation of sodium phosphate tablets

Douglas K. Rex, Howard Schwartz, Michael Goldstein, John Popp, Seymour Katz, Charles Barish, Robyn G. Karlstadt, Martin Rose, Kelli Walker, Sandra Lottes, Nancy Ettinger, Bing Zhang

Research output: Contribution to journalArticle

37 Scopus citations


OBJECTIVE: A residue-free sodium phosphate tablet (RF-NaP) was formulated that lacks microcrystalline cellulose, which can appear as a whitish residue in the colon. A multicenter, randomized, investigator-blinded study was conducted to compare the colon-cleansing efficacy of 40 or 32 tablets of RF-NaP with the marketed 40-tablet NaP treatment regimen. METHODS: Eight hundred sixteen patients were randomized prior to colonoscopy to receive either 40 tablets (60 g) of NaP or RF-NaP or 32 tablets (48 g) of RF-NaP. Colon cleansing was assessed using a 4-point scale based on retained "colonic contents." The primary end point was overall colon-cleansing response rate to treatment (score of excellent/good) versus nonresponse (fair/inadequate). RESULTS: Seven hundred four patients were included in the efficacy analysis. The overall colon-cleansing response rates were comparable among treatment arms (94.5%, 97.0%, and 95.3% for NaP, RF-NaP 40, and RF-NaP 32 tablets, respectively). Ascending colon-cleansing response rates for RF-NaP 40 (95.7%) and 32 tablets (93.6%) were significantly better than for NaP tablets (88.5%, p < 0.03 for both). Patients treated with RF-NaP 32 tablets experienced less pronounced changes in electrolyte levels and fewer adverse events (138/239, 58%) compared with patients receiving NaP (161/238, 68%, p = 0.07) and RF-NaP 40 tablets (156/236, 66%, p = 0.03). The most common adverse events reported were abdominal distention, nausea, abdominal pain, and vomiting. CONCLUSIONS: Based on the safety, efficacy, and patient preferences, the 32-tablet RF-NaP regimen was superior to the 40-tablet RF-NaP and NaP regimen for colon cleansing prior to colonoscopy.

Original languageEnglish (US)
Pages (from-to)2594-2604
Number of pages11
JournalAmerican Journal of Gastroenterology
Issue number11
StatePublished - Nov 1 2006


ASJC Scopus subject areas

  • Hepatology
  • Gastroenterology

Cite this

Rex, D. K., Schwartz, H., Goldstein, M., Popp, J., Katz, S., Barish, C., Karlstadt, R. G., Rose, M., Walker, K., Lottes, S., Ettinger, N., & Zhang, B. (2006). Safety and colon-cleansing efficacy of a new residue-free formulation of sodium phosphate tablets. American Journal of Gastroenterology, 101(11), 2594-2604.