CLINICAL PHARMACOLOGY
Mechanism Of Action
Sodium picosulfate is hydrolyzed by colonic bacteria to form an active metabolite: bis-(p-hydroxy-phenyl)-pyridyl-2-methane, BHPM, which acts directly on the colonic mucosa to stimulate colonic peristalsis. Magnesium oxide and citric acid react to create magnesium citrate in solution, which is an osmotic agent that causes water to be retained within the gastrointestinal tract.
Pharmacodynamics
The stimulant laxative activity of sodium picosulfate together with the osmotic laxative activity of magnesium citrate produces a purgative effect which, when ingested with additional fluids, produces watery diarrhea.
Pharmacokinetics
Absorption
Sodium picosulfate, which is a prodrug, is converted to its active metabolite, BHPM, by colonic bacteria. After administration of two doses of sodium picosulfate, magnesium oxide, and anhydrous citric acid separated by 6 hours in 16 healthy subjects, sodium picosulfate reached a mean Cmax of 3.2 ng/mL at approximately 7 hours (Tmax). After the first dose, the corresponding values were 2.3 ng/mL at 2 hours. The terminal half-life of sodium picosulfate was 7.4 hours.
Elimination
Metabolism and Excretion
The fraction of the absorbed sodium picosulfate dose excreted unchanged in urine was 0.19%. Plasma levels of the free BHPM were low, with 13 out of 16 subjects studied having plasma BHPM concentrations below the lower limit of quantification (0.1 ng/mL). Urinary samples show that the majority of excreted BHPM was in the glucuronide-conjugated form. Magnesium oxide and citric acid react in water to create magnesium citrate. Baseline uncorrected magnesium concentration reached a maximum (Cmax) of approximately 1.9 mEq/L, which occurred at 10 hours post initial dose administration (Tmax). This represents an approximately 20% increase from the baseline.
Use In Specific Populations
Pediatric Patients
Pharmacokinetics of picosulfate was studied in pediatric patients aged from 9 to 16 years old.
For picosulfate, the apparent clearance is from 316 to 409 L/h. The corresponding estimates for apparent volume of distribution are from 2457 to 3935 liters. The derived half-life using these model estimates would be 7 hours. The picosulfate reached the mean Cmax of 3.5 ± 2.1 ng/mL at approximately 6 to 7 hours (Tmax)
The baseline uncorrected mean serum magnesium concentration was 2.02 mEq/L at 10 hours after the first dose of sodium picosulfate, magnesium oxide, and anhydrous citric acid and ranged from 1.7 to 2.46 mEq/L in pediatric patients from 9 to 16 years of age.
Drug Interaction Studies
In an in vitro study using human liver microsomes, sodium picosulfate did not inhibit the major CYP enzymes (CYP 1A2, 2B6, 2C8, 2C9, 2C19, 2D6, and 3A4/5) evaluated. Based on an in vitro study using freshly isolated hepatocyte culture, sodium picosulfate is not an inducer of CYP1A2, CYP2B6, or CYP3A4/5.
Clinical Studies
Adults
The safety and efficacy of CLENPIQ has been established based on adequate and well-controlled studies of another oral product of sodium picosulfate, magnesium oxide and anhydrous citric acid. Below is a description of the results of these two adequate and well-controlled studies.
The colon cleansing efficacy of sodium picosulfate, magnesium oxide, and anhydrous citric acid was evaluated for non-inferiority against a comparator in two randomized, investigator-blinded, active-controlled, multicenter US trials in adult patients scheduled to have an elective colonoscopy. In all, 1195 adult patients were included in the primary efficacy analysis: 601 from Study 1, and 594 from Study 2. Patients ranged in age from 18 to 80 years (mean age 56 years); 61% were female and 39% male. Self-identified race was distributed as follows: 90% White, 10% Black, and less than 1% other. Of these, 3% self-identified their ethnicity as Hispanic or Latino.
Patients randomized to the sodium picosulfate, magnesium oxide, and anhydrous citric acid group in the two studies were treated with one of two dosing regimens:
- In Study 1, sodium picosulfate, magnesium oxide, and anhydrous citric acid were given by “Split-Dose” (evening before and day of) dosing, where the first dose was taken the evening before the colonoscopy (between 5:00 and 9:00 PM), followed by five (5) 8-ounce glasses of clear liquid, and the second dose was taken the morning of the colonoscopy (at least 5 hours prior to but no more than 9 hours prior to colonoscopy), followed by three (3) 8-ounce glasses of clear liquid.
- In Study 2, sodium picosulfate, magnesium oxide, and anhydrous citric acid were given by “Day-Before” (afternoon/evening before only) dosing, where both doses were taken separately on the day before the colonoscopy, with the first dose taken in the afternoon (between 4:00 and 6:00 PM), followed by five (5) 8-ounce glasses of clear liquid, and the second dose taken in the late evening (approximately 6 hours later, between 10:00 PM and 12:00 AM), followed by three (3) 8-ounce glasses of clear liquid.
The comparator was a preparation containing two liters of polyethylene glycol plus electrolytes solution (PEG + E) and two 5-mg bisacodyl tablets, administered the day before the procedure. All patients in both treatment groups were limited to a clear liquid diet on the day before the procedure (24 hours before).
The primary efficacy endpoint was the proportion of patients with successful colon cleansing, as assessed by blinded colonoscopists using the Aronchick Scale. The Aronchick scale is a tool used to assess overall colon cleansing. Successful colon cleansing was defined as bowel preparations with >90% of the mucosa seen and mostly liquid stool that were graded excellent (minimal suctioning needed for adequate visualization) or good (significant suctioning needed for adequate visualization) by the colonoscopist.
In both studies, the sodium picosulfate, magnesium oxide, and anhydrous citric acid combination was non-inferior to the comparator. In addition, sodium picosulfate, magnesium oxide, and anhydrous citric acid provided by Split-Dose dosing met the pre-specified criteria for superiority to the comparator for colon cleansing in Study 1. The comparator in that study was administered entirely on the day prior to colonoscopy. See Tables 3 and 4 below.
Table 3: Proportion of Patients with Successful Colon Cleansing in Study 1 Split-Dose Regimen
Sodium picosulfate, magnesium oxide, and anhydrous citric acid Split-Dose Regimen |
2 L PEG+E* with 2 x 5-mg bisacodyl tablets |
Difference between treatment groups |
% (n/N) |
% (n/N) |
Difference |
95% CI |
84% (256/304) |
74% (221/297) |
10% |
(3.4%, 16.2%)† |
* 2 L PEG + E = two liters polyethylene glycol plus electrolytes solution.
† Non-inferior and superior 2 L PEG+E with 2 x 5-mg bisacodyl tablets |
Table 4: Proportion of Patients with Successful Colon Cleansing in Study 2 Day-Before Regimen
Sodium picosulfate, magnesium oxide, and anhydrous citric acid Day-Before Regimen |
2 L PEG+E* with 2 x 5-mg bisacodyl tablets |
Difference between treatment groups |
% (n/N) |
% (n/N) |
Difference |
95% CI |
83% (244/294) |
80% (239/300) |
3% |
(-2.9%, 9.6%)‡ |
* 2 L PEG + E = two liters polyethylene glycol plus electrolytes solution.
‡ Non-inferior |
Pediatric Patients 9 Years Of Age And Older
The safety and efficacy of CLENPIQ in pediatric patients 9 years of age and older has been established based on another oral product of sodium picosulfate, magnesium oxide and anhydrous citric acid provided in powder packets for reconstitution.
Sodium picosulfate, magnesium oxide, and anhydrous citric acid was evaluated for colon cleansing in a randomized, assessor-blind, multicenter, dose-ranging, active-controlled study in 78 pediatric patients 9 years to 16 years of age. The majority of patients were female (68%), white (91%), and of non-Hispanic or non-Latino ethnicity (95%). The mean age was 12 years of age. All 78 patients were included in the primary efficacy analysis.
Patients aged 9 years to 12 years were randomized into 3 arms (1:1:1):
- Sodium picosulfate, magnesium oxide, and anhydrous citric acid one-half packet per dose administered as two doses
- Sodium picosulfate, magnesium oxide, and anhydrous citric acid one packet per dose administered as two doses
- comparator (oral PEG-based solution per local standard of care).
Patients aged 13 years to 16 years were randomized into 2 arms (1:1):
- Sodium picosulfate, magnesium oxide, and anhydrous citric acid one packet per dose administered as two doses
- comparator (oral PEG-based solution per local standard of care)
Patients randomized to sodium picosulfate, magnesium oxide, and anhydrous citric acid had two options for dosing, as determined by the investigator. The “Split Dose” regimen was the preferred method and the “Day Before” regimen was the alternative method if the “Split Dose” was not appropriate.
“Split-Dose” Regimen: (evening before and day of) dosing, where the first dose was taken the evening before the colonoscopy (between 5:00 and 9:00 PM), followed by five (5) 8-ounce glasses of clear liquid, and the second dose was taken the morning of the colonoscopy (at least 5 hours prior to but no more than 9 hours prior to colonoscopy), followed by three (3) 8-ounce glasses of clear liquid.
“Day-Before” Regimen: (afternoon/evening before only) dosing, where both doses were taken separately on the day before the colonoscopy, with the first dose taken in the afternoon (between 4:00 and 6:00 PM), followed by five (5) 8-ounce glasses of clear liquid, and the second dose taken in the late evening (approximately 6 hours later, between 10:00 PM and 12:00 AM), followed by three (3) 8-ounce glasses of clear liquid.
All patients randomized to sodium picosulfate, magnesium oxide, and anhydrous citric acid was limited to a clear liquid diet on the day before the procedure. Those who received the comparator were given dietary instructions per the trial site’s standard of care.
The primary efficacy endpoint was the proportion of patients with successful colon cleansing as defined as a rating of either “Excellent” (> 90% of mucosa seen, mostly liquid stool, minimal suctioning needed for adequate visualization) or “Good” (> 90% of mucosa seen, mostly liquid stool, significant suctioning needed for adequate visualization) using the Aronchick scale, as assessed by blinded colonoscopists.
The sodium picosulfate, magnesium oxide, and anhydrous citric acid regimen of one-half packet per dose administered as two doses did not demonstrate comparable efficacy to the comparator, PEG, in patients 9 to 12 years of age and is not a CLENPIQ recommended dosage regimen [see DOSAGE AND ADMINISTRATION].
The sodium picosulfate, magnesium oxide, and anhydrous citric acid regimen of one packet per dose administered as two doses demonstrated successful colon cleansing in both the 9 to 12 year age group and the 13 to 16 year age group. The efficacy rates were similar to those observed in the PEG groups, as shown in Table 5.
Table 5. Proportion of Patients 9 to 16 Years of Age with Successful Colon Cleansing1
|
Sodium Picosulfate, Magnesium Oxide, and Anhydrous Citric Acid, One Packet Administered as Two Doses either as Split Dose or Day Before Regimen2 |
PEG Comparator3 |
% (n/N) |
95% CI |
% (n/N) |
95% CI |
Age 9-12 |
88% (14/16) |
(62, 98) |
81% (13/16) |
(54, 96) |
Age 13-16 |
81% (13/16) |
(54, 96) |
86% (12/14) |
(57, 98) |
1 Successful colon cleansing as defined by “Excellent” or “Good” on the Aronchick scale
2 Of the 32 patients, 9 received the Split Dose Regimen and 23 the Day Before Regimen
3 Oral PEG-based preparation was used in the study as per standard of care |