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HalfLytely and Bisacodyl Tablets
Mechanism of Action
Polyethylene glycol (PEG), which is an osmotic agent, causes water to be retained within the gastrointestinal tract.
Bisacodyl is hydrolyzed by intestinal brush border enzymes and colonic bacteria to form an active metabolite [bis-(p-hydroxyphenyl) pyridyl-2 methane; (BHPM)] that acts directly on the colonic mucosa to produce colonic peristalsis.
The stimulant laxative effect of bisacodyl, together with the osmotic effect of the unabsorbed PEG when ingested with a large volume of water, produces watery diarrhea.
When taken orally, PEG 3350 is minimally absorbed.
Bisacodyl, which is a prodrug, is converted to its active metabolite BHPM by intestinal brush border enzymes and colonic bacteria. The pharmacokinetics of bisacodyl following oral administration of the bisacodyl tablet has not been adequately characterized.
The colon cleansing efficacy of HalfLytely and Bisacodyl Tablet Bowel Prep Kit (with 5 mg of bisacodyl) was evaluated in a randomized, single blind (endoscopist only), active-controlled, multicenter study. In this study, 293 adult patients were included in the efficacy analysis. Patients ranged in age from 19 to 87 years old (mean age 55 years old) with 55% female and 45% male patients. Race was distributed as follows: 83% White, 12% African American, 8% Hispanic or Latino, and 4% other.
Patients were randomized to one of the following two colon preparations: 1) HalfLytely and Bisacodyl Tablets (sodium chloride-sodium bicarbonate and potassium chloride) Bowel Prep Kit [10 mg of bisacodyl tablets were given at noon on the day before colonoscopy followed by 2 liters of HalfLytely (after the first bowel movement or maximum of 6 hours)] at a rate of 8 ounces every 10 minutes and 2) a modified HalfLytely and Bisacodyl Tablet Bowel Prep Kit [containing a 5 mg bisacodyl tablet given at noon on the day before colonoscopy followed by 2 liters of HalfLytely (after the first bowel movement or maximum of 6 hours)] at a rate of 8 ounces every 10 minutes.
Patients were instructed to refrain from solid food and to have clear liquids on the day before colonoscopy. In addition, patients were instructed to consume nothing by mouth, except clear liquids, from the time the preparation was completed until after the colonoscopy was completed.
The primary efficacy endpoint was the proportion of patients with successful colon cleansing (assessed by the colonoscopists), see Table 2 below. Successful colon cleansing was defined as preparations that were graded excellent (no more than small bits of adherent feces/fluid) or good (small amounts of feces or fluid not interfering with the exam) by the colonoscopist.
Table 2: Proportion of Patients with Successful Colon Cleansing
|HalfLytely and 5 mg Bisacodyl Tablet Bowel Prep Kit (H5)||HalfLytely and 10mg Bisacodyl Tablets Bowel Prep Kit (H10)||Difference between treatment groups (H5– H10)|
|% (n/N)||Two-sided 95% CI1||% (n/N)||Two-sided 95% CI1||Percent Difference %||Two-sided 95% CI for Percent Difference|
|All Patients||78 (114/147)||(69.9, 84.0)||80 (117/146)||(72.7, 86.3)||-2.0||(-11.9, 6.8)|
|1Confidence Interval (CI) for within treatment percent success is from an exact Chi Square test.|
The proportion of patients with successful colon cleansing was similar between treatment groups. No differences in response rates by gender or race were noted in the HalfLytely and 5 mg bisacodyl group. In patients ≥ 65 years of age treated with the HalfLytely and 5 mg Bisacodyl Tablet Bowel Prep Kit the proportion with successful colon cleansing was 67% (n=28/42)[ 95% CI: ( 50.5, 80.4)].
Last reviewed on RxList: 8/4/2010
This monograph has been modified to include the generic and brand name in many instances.
Additional HalfLytely and Bisacodyl Tablets Information
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