Hyperosmotic Laxatives (Monograph)

Brand names: Babylax, Colace, Colyte, Fleet, GoLYTELY, ... show all 11 brands HalfLytely, MiraLAX, MoviPrep, NuLYTELY, Sani-Supp, Trilyte
Drug class: Cathartics and Laxatives
ATC class: A06AG
VA class: IR100
CAS number: 56-81-5

Introduction

Glycerin, sorbitol, and polyethylene glycol (PEG 3350) are hyperosmotic laxatives.^{a b 238 245 246 247 248 253}

Uses for Hyperosmotic Laxatives

Constipation

Glycerin (rectally),^{238 239 240 241 242} sorbitol (rectally),^a and polyethylene glycol (PEG) 3350 (MiraLAX; orally)²⁴⁴ may be used for relief of occasional constipation.^{238 239 240 241 242 244} However, rectal suppositories or enemas should not be used when oral laxatives are effective.^b

Glycerin and sorbitol may be used to treat constipation occurring during pregnancy or the puerperium; however, bulk-forming laxatives or stool softeners are usually preferred.^b

May avoid or relieve constipation with proper diet (high fiber content [e.g., bran]), adequate fluid intake, prompt response to the defecation reflex, and exercise.^b

Avoid use of laxatives in infants and children; treat childhood constipation by counseling parents regarding acceptable variations in the frequency of bowel movements.^b

Bowel Cleansing

PEG 3350 electrolyte solutions are used to empty the bowel prior to colonoscopy and barium enema radiologic examinations.^{245 246 247 248 252 253} Glycerin and sorbitol also have been used prior to these procedures, but these laxatives do not always entirely empty the colon.^b

The American Society of Colon and Rectal Surgeons (ASCRS), American Society for Gastrointestinal Endoscopy (ASGE), and Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) recommend the use of PEG 3350 electrolyte solutions in patients with electrolyte or fluid imbalances (e.g., those with renal or liver insufficiency, CHF, liver failure, advanced liver disease with ascites).^{251 259} These experts also recommend use of PEG 3350 electrolyte solutions for colonic cleansing in infants and children.²⁵¹

Sorbitol as an Adjunct to Sodium Polystyrene Sulfonate

Sorbitol is used orally or rectally to facilitate the passage of sodium polystyrene sulfonate (a resin) through the intestinal tract, prevent constipation caused by the resin, aid in potassium removal, and improve the palatability of the resin.^{b 256}

Hyperosmotic Laxatives Dosage and Administration

General

• Prior to bowel cleansing, provide a copy of the patient information provided by the manufacturer containing careful instructions on the proper methods of reconstitution and administration of the laxatives.^{245 246 247 248 253}

Administration

Administer sorbitol rectally; may administer orally when used as an adjunct to sodium polystyrene sulfonate.^a

Administer glycerin solution^{239 242} and suppositories^{a 238 240 241 254 255} rectally.^{a b}

Administer PEG 3350 electrolyte solutions orally or through a nasogastric tube.^{244 245 246 247 248 253}

Oral or Nasogastric Administration (PEG 3350, PEG 3350 with Electrolytes)

Reconstitution

When used for constipation, reconstitute PEG 3350 powder for oral solution (MiraLAX) with 120–240 mL of water (cold, room temperature, or hot).²⁴⁴

When used for bowel cleansing, reconstitute PEG 3350 powder (with electrolytes) for oral or nasogastric solution with the appropriate amount of lukewarm water as directed by the manufacturer.^{245 246 247 248 252 253}

Shake solution vigorously until ingredients are dissolved; additional ingredients (flavorings other than those provided by the manufacturers) not recommended.^{245 246 247 248 253}

Refrigerate the reconstituted solution.^{245 246 247 248 252 253} Palatability of oral solution may be increased if the reconstituted solution is chilled prior to administration;^{245 247} however, a chilled PEG 3350 electrolyte solution is not recommended for infants.²⁵³

Administration of PEG 3350 Electrolyte Solution for Bowel Cleansing

Fast for approximately 3 or 4 hours before administration of PEG 3350 electrolyte solution.^{245 246 247 253} Do not eat solid foods for at least 2 hours prior to administration.^{245 246 247 252 253}

Administer PEG 3350 electrolyte solutions orally, but may give through a nasogastric tube if patients are unwilling or unable to drink the solution.^{245 246 247}

Rapid drinking of each PEG 3350 electrolyte solution portion preferred to drinking small amounts continuously.^{245 252 253}

PEG 3350 electrolyte solutions may be given by single-dose regimens (usually on the evening prior to the colonoscopy [e.g., 6 p.m.] or if procedure is scheduled for midmorning or later allowing patients 3 hours for drinking and 1 hour for complete bowel evacuation)^{245 248 251 261 262} or by divided-dose regimen (usually consuming a portion on the evening prior to the colonoscopy and the remaining solution on the morning of the colonoscopy).^{248 251 261 262}

Clinical studies suggest that the divided-dose PEG 3350 electrolyte solution regimen (e.g., 2–3 L the evening before and 1 L the morning of the procedure) is superior to the standard single-dose regimen (e.g., 4 L administered on the evening prior to the procedure).^{251 261 262}

In one study, PEG 3350 electrolyte solution consumption <5 hours before colonoscopy was superior to a regimen administered ≥19 hours before the procedure.^{251 260} If a patient has an afternoon colonoscopy, administer a portion of the PEG 3350 solution on the morning of the colonoscopy to improve bowel cleansing results.^{251 260}

Administration Precautions (PEG 3350 Electrolyte Solution)

Use PEG 3350 electrolyte solutions with caution in patients with impaired gag reflex, unconscious or semiconscious patients, and those prone to regurgitation or aspiration; observe these patients during administration, especially if solution is administered through a nasogastric tube.^{245 246 247 248 252}

If severe discomfort or distention occurs while consuming PEG 3350 electrolyte solutions, slow or temporarily discontinue administration until symptoms abate.^{246 253}

Rectal Administration (Glycerin)

Moisten regular glycerin suppositories with lukewarm water prior to insertion.^b With steady pressure, gently insert suppository tip high into rectum.^{b 238 240 241 254 255} Instruct patient to retain the suppository for 15 minutes; not required to melt to produce laxative action.^{238 240 241 254 255} Discontinue use if resistance is encountered.²³⁹

Before administering glycerin laxative enemas, have patient initially lie on left side with right knee bent and arms resting comfortably^{239 242} or kneel on the bed with the head and chest lowered and forward until the left side of the face is resting on the surface of the bed.^b With steady pressure, insert enema nozzle into rectum with side-to-side movement with tip pointing toward navel until the entire dose is expelled.^{b 239 242} While squeezing the container, remove tip from rectum and discard unit.^{239 242} Discontinue use if resistance is encountered.^{239 242} Enema fluids, if properly introduced, usually provide adequate evacuation if retained until definite lower abdominal cramping is felt.^b

Dosage

Administer laxatives at infrequent intervals in single doses^a at the lowest effective dosage level, and usually for periods not exceeding 1 week; use for longer periods only under the management of a clinician and as part of a carefully planned therapeutic regimen.^b

Only extremely high oral doses of sorbitol (25 g daily) or glycerin exert laxative action.^b

Pediatric Patients

Constipation

Glycerin

Rectal

Children 2 to <6 years of age: 1–1.2 g as a suppository^{240 241} or 2.3 g (2.3 mL) as an enema.²⁴²

Children ≥6 years of age: 2–2.1 g as a suppository^{238 240} or 5.6 g (5.5 mL) as an enema.²³⁹

If a bowel movement does not occur after using the glycerin suppository or enema, discontinue drug.^{239 241 242}

Sorbitol

Rectal

Children 2–11 years of age: 30–60 mL of sorbitol 25–30% solution as an enema. ^a

Children ≥12 years of age: 120 mL of sorbitol 25–30% solution as an enema.^a

Bowel Cleansing

PEG 3350 (with Electrolytes)

Nasogastric

Children ≥6 months of age: 25 mL/kg (2.6 g/kg) per hour (NuLYTELYor Trilyte) until watery stool is clear or 4 L is consumed.^{246 253}

Oral

Children ≥6 months of age: 25 mL/kg (2.6 g/kg) per hour (NuLYTELYor Trilyte) until watery stool is clear or 4 L is consumed.^{246 253}

Adults

Constipation

Glycerin

Rectal

2–2.1 g as a suppository^{238 240} or 5.6 g (5.5. mL) as an enema.²³⁹

If a bowel movement does not occur after using the glycerin suppository, discontinue drug.²³⁸

Sorbitol

Oral

15 mL of sorbitol 70% solution until diarrhea occurs, as an adjunct to sodium polystyrene sulfonate; alternatively, 20–100 mL as an oral vehicle for the resin.^{a 256}

Rectal

120 mL of sorbitol 25–30% solution as an enema.^a

120 mL of sorbitol 25–30% solution as an enema, used as an adjunct to sodium polystyrene sulfonate.^{a 256}

PEG 3350

Oral

17 g (MiraLAX) daily as needed for up to 7 days.²⁴⁴

Bowel Cleansing

PEG 3350 (with Electrolytes)

Nasogastric

4 L at a rate of 20–30 mL (1.18–1.77 g [Golytely]; 2.1–3.15 g [Nulytely]; 1.2–1.8 g [Colyte]) per minute (1.2–1.8 L/hour).^{245 246 247 251 259}

Oral

Single-dose regimen: 240 mL (about 14 g [GoLYTELY], 25 g [NuLYTELY], about 14 g [Colyte], 25 g [Trilyte]) every 10 minutes until rectal output is clear or 4 L is consumed.^{245 246 247 253 259}

Single-dose regimen: 240 mL (24 g [MoviPrep]) every 15 minutes until 1 L is consumed; repeat 1.5 hours later and drink an additional 1 L of clear liquid.²⁴⁸

Divided-dose regimen: Evening before procedure, 240 mL (24 g [MoviPrep]) every 15 minutes until 1 L is consumed; drink an additional 0.5 L of clear liquid.²⁴⁸ On the morning of the procedure, 240 mL (24 g [MoviPrep]) every 15 minutes until 1 L is consumed; drink an additional 0.5 L of clear liquid at least 1 hour prior to the procedure.²⁴⁸

Combination PEG 3350 electrolyte solution and bisacodyl (HalfLytely): Initially, 20 mg (four 5-mg bisacodyl delayed-release tablets); wait for a bowel movement (or maximum of 6 hours).^{252 259} Follow with 240 mL of PEG 3350 electrolyte solution every 10 minutes until 2 L has been consumed.²⁵²

Prescribing Limits

Pediatric Patients

Constipation

Glycerin

Rectal

Children 2 to <6 years of age: Maximum 1.2 g (as suppository) daily^{240 241} or 2.3 g (2.3 mL) (as an enema) daily.²⁴²

Children ≥6 years of age: Maximum 2.1 g (as suppository) daily^{238 240} or 5.6 g (5.5 mL) (as an enema) daily.²³⁹

Adults

Constipation

Glycerin

Rectal

Maximum 2.1 g (as suppository) daily^{238 240} or 5.6 g (5.5 mL) (as an enema) daily.²³⁹

PEG 3350

Oral

17 g (MiraLAX) daily for up to 7 days.²⁴⁴

Special Populations

No special population dosage recommendations at this time.^{b 238}

Cautions for Hyperosmotic Laxatives

Contraindications

• Acute abdominal pain, nausea, vomiting, symptoms of appendicitis or undiagnosed abdominal pain.^b

• PEG 3350 electrolyte solutions: Most manufacturers state that these solutions are contraindicated in patients with GI obstruction, gastric retention, bowel perforation, toxic colitis, toxic megacolon, or ileus.^{245 246 247 252}

• Hypersensitivity to drug or any ingredient in the formulation.^{244 245 246 247 248 249 252}

Warnings/Precautions

Warnings

Long-term or Chronic Use

Long-term use of laxatives has been associated with laxative dependence, chronic constipation, and loss of normal bowel function.^b

Chronic use or overdosage of laxatives may produce persistent diarrhea, hypokalemia, loss of essential nutritional factors, and dehydration.^b

Seizures Associated with Electrolyte Abnormalities

Generalized tonic-clonic seizures associated with electrolyte abnormalities (e.g., hyponatremia, hypokalemia) have been reported following use of PEG 3350 electrolyte solutions for bowel cleansing in patients without a history of seizures.²⁴⁸ Such neurologic effects resolved with correction of fluid and electrolyte abnormalities.²⁴⁸

Use PEG 3350 electrolyte solutions with caution in patients receiving drugs that increase risk of electrolyte abnormalities (e.g., diuretics, ACE inhibitors).²⁴⁸ Consider performing baseline and postcolonoscopy electrolyte tests in these patients.²⁴⁸

Ulcerative Colitis

Use PEG 3350 electrolyte solutions (Golytely, Colyte, MoviPrep) with caution in patients with severe ulcerative colitis.^{245 247 248}

Combined Preparations

When used in combination with bisacodyl, consider the precautions, cautions, and contraindications associated with bisacodyl.²⁵²

If large volumes of liquid containing sugars (e.g., Gatorade) are added to PEG 3350 (with electrolytes) powder for solution, the sugars may reach the colon and be converted to methane or other flammable gases.²⁵⁹ If electrocautery is used for polyp removal, possible risk that such gases could ignite and explode.²⁵⁹

Sensitivity Reactions

Following administration of PEG 3350 electrolyte solutions, isolated cases of urticaria, rhinorrhea, dermatitis, and, rarely, anaphylactic reactions have been reported.^{245 248 253}

General Precautions

Phenylketonuria

Individuals with phenylketonuria and other individuals who must restrict their intake of phenylalanine should be warned that MoviPrep (PEG 3350 electrolyte solution) contains aspartame (NutraSweet), which is metabolized in the GI tract to provide a maximum of 2.33 mg of phenylalanine per treatment (2 L of solution).^{248 264 265 266 267 268}

Glucose-6-Phosphate Dehydrogenase (G-6-PD)

MoviPrep (PEG 3350 electrolyte solution) contains 5.9 g of sodium ascorbate and 4.7 g of ascorbic acid.²⁴⁸ Use with caution in patients with G-6-PD deficiency (especially those with active infection, history of hemolysis, or taking concomitant drugs known to precipitate hemolytic reactions),²⁴⁸ since patients with G-6-PD deficiency have developed hemolysis after large IV or oral doses of ascorbic acid.²⁶³

GI Effects

Glycerin: If rectal bleeding occurs, discontinue the drug and consult a clinician.^{238 239 241}

PEG 3350 solution (MiraLAX): If rectal bleeding, nausea, bloating, cramping, or abdominal pain worsens, or the patient requires >7 days of use or experiences diarrhea, discontinue the drug and contact a clinician.²⁴⁴

PEG 3350 electrolyte solutions: If severe bloating, distention, or abdominal pain occurs, slow or temporarily discontinue administration until symptoms subside.^{245 246 248 252} If GI obstruction or perforation is suspected, perform appropriate tests to rule out these conditions before PEG 3350 electrolyte solution administration.^{248 252}

Specific Populations

Pregnancy

Category C (PEG 3350 electrolyte solution).^{245 246 247 248 251 253}

Lactation

Not known whether PEG 3350 electrolyte solution is distributed into milk.²⁴⁸ Use with caution in nursing women.²⁴⁸

Pediatric Use

Avoid use of laxatives in infants and children; childhood constipation is best treated by counseling parents on acceptable variations in the frequency of bowel movements.^b

Safety and efficacy of glycerin preparations not established in pediatric patients <2 years of age.^{238 239 240 241 242}

PEG 3350 (MiraLAX): Safety and efficacy not established in pediatric patients <17 years of age.²⁴⁴

PEG 3350 electrolyte solutions (NuLYTELY, Trilyte): Safety and efficacy not established in pediatric patients <6 months of age.^{246 253} Closely monitor children <2 years of age receiving NuLYTELY for signs of hypoglycemia.²⁴⁶

PEG 3350 electrolyte solutions (GoLYTELY, Colyte, MoviPrep): Safety and efficacy not established in pediatric patients.^{245 247 248}

Geriatric Use

PEG 3350 electrolyte solutions (MoviPrep, HalfLytely): No substantial differences in safety and efficacy relative to younger adults.^{248 252}

PEG 3350 electrolyte solutions (MoviPrep): Possibility exists of greater sensitivity to the drug in some geriatric individuals.²⁴⁸

Serious adverse reactions (e.g., Mallory-Weiss syndrome, asystole, sudden dyspnea with pulmonary edema, infiltrates on chest radiograph after vomiting and aspirating PEG 3350) reported in patients >60 years of age receiving PEG 3350 electrolyte solutions.^{245 247 248 253}

Renal Impairment

Use laxative products containing >50 mEq of magnesium, >25 mEq of potassium, or ≥1 mEq of sodium per dose with caution in patients with renal disease and only under supervision of a clinician.^b Monitor electrolytes.^b

Common Adverse Effects

Glycerin (rectal): Rectal discomfort,^b burning,^{b 238 239 241} or irritation;^b rectal mucosa hyperemia (with minimal hemorrhage and mucus discharge);^b griping;^b cramping pain;^b tenesmus.^b

Sorbitol (rectal) used as adjunct to sodium polystyrene sulfonate: Diarrhea.^b

PEG 3350 electrolyte solutions (oral or nasogastric): Malaise, nausea,^{245 246 248 259} abdominal distention,^{245 246 248} abdominal fullness and/or bloating,^{245 246 247 248 259} abdominal cramps,^{245 246 247 248} vomiting,^{245 246 247 248 259} anal irritation,^{245 246 247 248} thirst.²⁴⁸

Drug Interactions

By increasing intestinal motility, laxatives may potentially decrease transit time of concomitantly administered oral drugs and decrease their absorption;^b administer other oral drugs at least 1 hour before PEG 3350 electrolyte solution.^{245 246 247 248 252 253}

Hyperosmotic Laxatives Pharmacokinetics

Absorption

Bioavailability

Following rectal administration, glycerin and sorbitol are poorly absorbed. ^a

Onset

Following rectal administration of glycerin suppositories or enemas, colonic evacuation occurs within 15–60 minutes.^{a 239 240 242 250}

Following rectal administration of sorbitol, colonic evacuation occurs within 24–48 hours.²⁵⁰

Following oral administration of PEG 3350 (MiraLAX), colonic evacuation occurs in 1–3 days.²⁴⁴

Following oral administration of PEG 3350 electrolyte solution and bisacodyl (HalfLytely), colonic evacuation occurs in approximately 1–6 hours.²⁵²

Following oral administration of PEG 3350 electrolyte solutions (GoLYTELY, NuLYTELY, Colyte, MoviPrep, Trilyte), initial bowel movement usually occurs within 1 hour.^{245 246 247 248 250 253}

Duration

Following oral administration of PEG 3350 electrolyte solutions (GoLYTELY, NuLYTELY, Trilyte), complete bowel evacuation occurs within 4 hours.^{245 246 253}

Distribution

Extent

Not known whether PEG 3350 (MiraLAX) is distributed into human milk.²⁴⁸

Elimination

Metabolism

Sorbitol, a nonabsorbable disaccharide, metabolized by colonic bacteria into acetic and other short chain fatty acids.²⁵⁰

Stability

Storage

Oral

PEG 3350 Powder for Solution

MiraLAX: 20–25°C.²⁴⁴

PEG 3350 (with Electrolytes) Powder for Solution

Colyte: 20–25°C (may be exposed to 15–30°C).²⁴⁷ Following reconstitution, refrigerate and use within 48 hours; discard unused portions.²⁴⁵

GoLYTELY: Tight containers at 15–30°C.²⁴⁵ Following reconstitution, refrigerate and use within 48 hours; discard unused portions.²⁴⁵

MoviPrep: 25°C (may be exposed to 15-30°C).²⁴⁸ Following reconstitution, refrigerate and use within 24 hours.²⁴⁸

NuLyTELY: Tight containers at 25°C.²⁴⁶ Following reconstitution, refrigerate and use within 48 hours; discard unused portions.²⁴⁶

Oral or Rectal

Sorbitol 70% Solution

15–30° C.²⁵⁷

Rectal

Glycerin Suppositories

Tightly closed^{238 241} or well-closed containers²⁵⁵ <25°C.^a Avoid excessive heat.^{254 255}

Actions

• Precise mechanisms of action of laxatives not known.^b

• When administered rectally, glycerin and sorbitol exert hygroscopic and/or local irritant action, drawing water from the tissues into feces and reflexively stimulating evacuation.^{b 240}

• PEG 3350 electrolyte solution is a nonabsorbable solution that passes through the bowel without net absorption or secretion; therefore, substantial fluid and electrolyte shifts are avoided.^{245 246 247 248 251 253 259}

• PEG 3350 electrolyte solution osmotically increases intraluminal fluids to induce diarrhea and rapidly cleanse the bowel.^{245 246 247 248 250}

Advice to Patients

• Importance of providing patient with manufacturer’s instructions for reconstitution of PEG 3350 electrolyte solutions.^{245 247}

• Inform patients that PEG 3350 electrolyte solutions for colonic cleansing are more palatable if chilled prior to administration;^{245 246 247} do not use chilled solutions in infants.^{246 253}

• Importance of advising patients not to consume solid foods 2 hours (preferably 3–4 hours) before drinking PEG 3350 electrolyte solutions.^{245 246 247 253}

• Importance of advising patients to drink 240 mL (8 ounces) of PEG 3350 electrolyte solution every 10 minutes; rapid drinking of each portion is preferable to drinking small amounts continuously.^{245 246 247 253}

• Abdominal bloating and distention may develop before bowel movement; if severe discomfort or distention occurs, stop drinking the solution temporarily or drink each portion at longer intervals, until symptoms abate.^{245 246 248 253}

• Inform patients that first bowel movement will occur approximately 1 hour after starting PEG 3350 electrolyte solution.^{245 246 247 248 253}

• Continue drinking until watery stool is clear of solid matter.^{245 246 247 253} Discard any unused portion.^{245 246 247 253}

• Importance that patients adequately hydrate before, during, and after taking PEG 3350 solution (MiraLAX). ²⁴⁸

• Inform patients taking PEG 3350 solution (MiraLAX) that it may take 1–3 days after starting the drug to have a bowel movement.²⁴⁴

• Importance of informing patients taking PEG 3350 electrolyte solutions and bisacodyl (HalfLytely) to avoid consumption of large quantities of water during or after preparation for colonoscopy.²⁵²

• Instruct patients to take other oral drugs at least 1 hour before administering PEG 3350 electrolyte solution to minimize possible interference with absorption.^{245 246 247 248 252}

• Importance of informing clinicians before using laxatives if abdominal pain, nausea, or vomiting is present, if there has been any sudden change in bowel habits lasting >2 weeks reported, or if use of laxatives for 1 week has had no effect.^{b 238 239 241 242 244}

• Importance of discontinuing use and informing a clinician if rectal bleeding develops or a bowel movement fails to occur after use; possible symptoms of a serious condition.^{238 239 241 242 244}

• Importance of not using laxative products for >1 week unless directed by a clinician.^{b 238 244}

• Importance of informing clinicians of existing or contemplated concomitant therapy (especially other laxatives), including prescription and OTC drugs, as well as any concomitant illnesses.²⁴⁴

• Importance of taking only as prescribed; do not increase dosage or duration of therapy unless otherwise instructed by a clinician.²⁴⁴

• Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.^{244 243 245 246 247 248 251 253}

• Importance of informing patients of other important precautionary information. (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

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