Efficacy and Safety of a New Sodium Phosphate (NaP) Tablet Bowel Purgative vs a 2 L Polyethylene Glycol (PEG) Electrolyte Lavage Solution Plus Bisacodyl in the Elderly

Abstract

Purpose: A new NaP tablet formulation (OsmoPrep™; Salix Pharmaceuticals, Inc) was recently approved for colon cleansing prior to colonoscopy. Because colonoscopies are frequently performed in the elderly, a subanalysis of patients (pts) aged ≥65 y assessed the efficacy and safety of NaP tablets vs 2 L PEG plus bisacodyl tablets bowel prep kit (HalfLytely®; Braintree Laboratories, Inc) as a bowel purgative for screening colonoscopy. Methods: Pts ≥18 y were randomized in a phase 3, investigator-blinded, multicenter study to receive 32 NaP tablets (48 g) or 2 L PEG + 4 bisacodyl tablets (20 mg). NaP tablets were taken 4 at a time with 8 oz clear liquid on the evening before (n = 20) and 3 to 5 h prior to (n = 12) colonoscopy. 2 L PEG + bisacodyl was taken as directed in US prescribing information. Overall colon cleansing was assessed by the investigator, using a 4-point scale based on colonic contents (1 = excellent, 2 = good, 3 = fair, 4 = inadequate). Adverse events were recorded from the first dose of study medication to 48 h (+ 2 days) postcolonoscopy. Vital signs and clinical lab evaluations were conducted at screening, the day of, and 48 h (+2 days) postcolonoscopy. Results: 207 pts taking NaP tablets and 208 pts taking 2 L PEG + bisacodyl underwent colonoscopy, with 49 and 50 pts in each group (grp) aged ≥65 y, respectively. Within treatment grps, mean colon-cleansing scores were comparable across age grps (1.5 ± 0.77 and 1.5 ± 0.68 for pts <65 y and ≥65 y with NaP tablets; 1.8 ± 0.77 and 1.9 ± 0.77 for pts <65 y and ≥65 y with 2 L PEG plus bisacodyl). However, between treatment grps, NaP tablets exhibited significantly better colon-cleansing scores vs 2 L PEG + bisacodyl in both age grps (P≤ 0.028). In pts aged ≥65 y, abdominal distension and vomiting occurred less frequently with NaP tablets vs 2 L PEG plus bisacodyl (P≤ 0.0277). In general, for pts taking NaP tablets, both age grps exhibited transient shifts from mean screening levels in serum electrolytes measured. In addition, no differences between treatment grps were observed in serum creatinine or BUN levels in older pts. Conclusions: NaP tablets were safe and efficacious as a bowel purgative in elderly pts, providing significantly better colon cleansing and tolerability profile vs a 2 L PEG plus bisacodyl.