Residue-free sodium phosphate tablets (OsmoPrep) versus Visicol for colon cleansing: a randomized, investigator-blinded trial.

BACKGROUND: The bowel purgative Visicol contains microcrystalline cellulose (MCC) residue, which may impair full visibility during a colonoscopy. An MCC residue-free sodium phosphate (RF-NaP; OsmoPrep) tablet was developed. OBJECTIVE: To investigate appropriate RF-NaP dosing. DESIGN: Phase 2, randomized, investigator-blinded study. SETTING: Six research centers in the United States. PATIENTS AND INTERVENTIONS: Patients undergoing a colonoscopy received Visicol (n = 34) or 1 of 6 RF-NaP regimens administered as either split (S) dosing (the evening before and the day of colonoscopy) or evening-only (E) dosing. Dosing regimens for RF-NaP were 40 tablets S, 3 every 15 minutes (n = 33); 40 tablets S, 4 every 15 minutes (n = 34); 32 tablets E, 4 every 15 minutes (n = 34); 32 tablets S, 4 every 15 minutes (n = 36); 28 tablets E, 4 every 15 minutes (n = 34); 28 tablets S, 4 every 15 minutes (n = 34). Visicol was administered as 40 tablets S, 3 every 15 minutes. MAIN OUTCOME MEASURE: Overall colon cleansing (OCC) was assessed by a physician questionnaire (4-point scale, based on colonic contents). An OCC rating of "excellent" or "good" was considered a response. Safety measures were also monitored. RESULTS: Split dosing with RF-NaP was associated with high OCC and achieved response rates of 90%, 97%, and 100% for 28, 32, and 40 tablets, respectively, compared with 86% for Visicol. In addition, RF-NaP evening-only regimen response rates were 90% (32 tablets) and 72% (28 tablets). Transient shifts in electrolyte levels were reduced, and GI adverse events were less common with lower RF-NaP dose regimens. CONCLUSIONS: Administration of RF-NaP retains the benefits of a tablet purgative but eliminates MCC issues. Split dosing and 32-tablet evening-only dosing of RF-NaP tablets were efficacious and well tolerated, and split dosing of RF-NaP tablets is recommended.

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

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.