Laxatives (1)

Mosby items and derived items ©

2005, 2002 by Mosby, Inc.

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*Abnormally infrequent and difficult passage offeces through the lower GI tract

*Symptom, not a disease

*Disorder of movement through the colonand/or rectum

*Can be caused by a variety of diseasesor drugs

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*Constipation is generally defined as infrequent and/or

unsatisfactory defecation fewer than 3 times per week.

*Patients may define constipation as passing hard stools

or straining, incomplete or painful defecation.

Epidemiology

2-27% of the population has constipation

Constipation affects twice as many women

as men

Constipation is more prevalent in non-White

persons than in White persons (non-

White:White ratio range 1.11--2.89)

Causes of constipation

Diet

Lack of exercise

Age

Irregular bowel habits

Drug induced

Disease States/Conditions

Spasam of sigmoid colon

Dysfunction of myenteric plexus

I’m constipated, now what?

Two approaches to consider:

Non-drug Approach

Drug Approach

* 1. Exercise - Fibre in the diet -

Fluid Intake

No evidence that increased exercise is beneficial in

severe constipation

Aim for 25-30g fibre/day

Unless dehydrated, increasing fluid does not relieve

chronic constipation and may increase the risk of fluid

overload eg heart or renal failure



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*Bulk forming

*Emollient

*Hyperosmotic

*Saline

*Stimulant



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1. Bulk forming

*High fiber

*Absorbs water to increase bulk

*Distends bowel to initiate reflex bowel activity

Examples:

*psyllium (Metamucil)

*methylcellulose (Citrucel)

*polycarbophil

Improve stool consistency and frequency with regular

use

Ensure good fluid intake to prevent faecal

impaction

Onset of action 2-3 days

Side Effects may include bloating, flatulence,

distension



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2. Emollient

*Stool softeners and lubricants

*Promote more water and fat in the stools

*Lubricate the fecal material and intestinalwalls

Examples:

*Stool softeners: docusate salts (Colace, Surfak)

*Lubricants: mineral oil

*Stool softener may take days to become

effective.

*They should not be taken together with mineral

oil because of the potential for absorption of the

mineral oil.

*Lubricant laxatives include Mineral oil and

glycerin suppositories.

* They facilitate the passage of hard stools.

*Mineral oil should be taken orally in an upright

position to avoid its aspiration and potential for

lipid or lipoid pneumonia.



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3. Hyperosmotic

*Increase fecal water content

*Result: bowel distention, increased peristalsis,and evacuation

Examples:

*polyethylene glycol (GoLYTELY)

*sorbitol

*glycerin

*lactulose (Chronulac)

*PEG powder for solution is available as a

prescription and also an over-the-counter

laxative.

*Lactulose is a semisynthetic disaccharide sugar

that also acts as an osmotic laxative. It is a

product that cannot be hydrolyzed by intestinal

enzymes. Oral doses are degraded in the colon

by colonic bacteria into lactic, formic, and

acetic acids. This increases osmotic pressure,

thereby accumulating fluid, distending the

colon, creating a soft stool, and causing

defecation.



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Saline

*Increase osmotic pressure within the intestinaltract, causing more water to enter theintestines

*Result: bowel distention, increased peristalsis,and evacuation



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Saline laxative; saline cathartic; examples:

*magnesium sulfate (Epsom salts)

*magnesium hydroxide (MOM)

*magnesium citrate

*sodium phosphate (Fleet Phospho-Soda, Fleetenema)

*Saline cathartics are nonabsorbable salts

(anions and cations) that hold water in the

intestine by osmosis and distend the bowel.

*increasing intestinal activity and producing

defecation in a few hours.

*Electrolyte solutions containing polyethylene

glycol (PEG) are used as colonic lavage solutions

to prepare the gut for radiologic or endoscopic

procedures.



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4. Stimulant

*Increases peristalsis via intestinal nervestimulation

Examples:

*castor oil

*senna

*cascara

*bisacodyl

*Senna is a widely used stimulant laxative.

* Its active ingredient is a group of sennosides,

a natural complex of anthraquinone glycosides.

*Taken orally, it causes evacuation of the

bowels within 8 to 10 hours.

*It also causes water and electrolyte secretion

into the bowel.

*In combination products with a docusate-

containing stool softener, it is useful in treating

opioid-induced constipation.

*Bisacodyl, available as suppositories and enteric-

coated tablets, is a potent stimulant of the colon.

*It acts directly on nerve fibers in the mucosa of the

colon.

*Adverse effects include abdominal cramps and the

potential for atonic colon with prolonged use.

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*Antacids should not be taken at the same

time as the enteric-coated tablets. The

antacid would cause the enteric coating

to dissolve prematurely in the stomach,

resulting in stomach irritation and pain.

*The same adverse effects could be

expected with milk, H2-receptor

antagonists, and PPIs

*Castor oil is broken down in the small

intestine to ricinoleic acid, which is very

irritating to the gut, and promptly increases

peristalsis.

*It should be avoided by pregnant patients,

because it may stimulate uterine

contractions.



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*Bulk forming

*Impaction

*Fluid overload

*Emollient

*Skin rashes

*Decreased absorption of vitamins

*Hyperosmotic

*Abdominal bloating

*Rectal irritation



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* Saline

*Magnesium toxicity (with renal insufficiency)

*Cramping

*Diarrhea

*Increased thirst

* Stimulant

*Nutrient malabsorption

*Skin rashes

*Gastric irritation

*Rectal irritation



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*All laxatives can cause electrolyteimbalances!



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*Obtain a thorough history of presentingsymptoms, elimination patterns, andallergies

*Assess fluid and electrolytes beforeinitiating therapy

*Patients should not take a laxative orcathartic if they are experiencing nausea,vomiting, and/or abdominal pain



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*A healthy, high-fiber diet and increased

fluid intake should be encouraged as an

alternative to laxative use

*Long-term use of laxatives often results in

decreased bowel tone and may lead to

dependency

*All laxative tablets should be swallowed

whole, not crushed or chewed, especially

if enteric coated



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*Patients should take all laxative tablets with6 to 8 ounces of water

*Patients should take bulk-forming laxativesas directed by the manufacturer with at least240 mL (8 ounces) of water



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*Bisacodyl and cascara sagrada should begiven with water due to interactions withmilk, antacids, and H2 blockers

*Patients should contact their

physician if they experience severe

abdominal pain, muscle weakness,

cramps, and/or dizziness, which may

indicate possible fluid or electrolyte

loss



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*Monitor for therapeutic effect

Health & Medicine

Laxatives (1)