Laxatives & Antidiarrheal Agents

Nonpharmacological treatment of constipation

• Fiber + fluid

• Prebiotics (substances that feed normal gut flora)

• Probiotics (live strains of good bacteria)

• Behavioral therapy

• Juices containing sorbitol (prunes)

• Activity/exercise/ambulation

Appropriate use of laxatives

• Relieve constipation for weakened abdominal and perineal muscles 

• Receiving drugs that decrease intestinal motility (e.g. opioids)

• Prevent straining in patients with CAD (e.g., post–myocardial infarction), HTN, cerebrovascular disease, and hemorrhoids and other rectal conditions

• Empty the bowel in preparation for bowel surgery or diagnostic procedures 

• Accelerate elimination of potentially toxic substances from the GI tract 

• Prevent absorption of intestinal ammonia in patients with hepatic encephalopathy

• Obtain a stool specimen for parasitologic examination

• Accelerate excretion of parasites after anthelmintic drugs have been administered

• Reduce serum cholesterol levels (psyllium products)

Laxative C/I

• Undiagnosed abd pain, nausea, or cramps

• Fecal impaction or bowel obstruction (can cause inflammation or rupture of organs)

• Habitual use

  • Weight loss (laxative abuse)

  • Chronic use (prolonged use can cause bowels to lose reflexes and be lazy; fluid & electrolytes imbalance

Steps in using laxatives

Lifestyle modifications (nonpharm interventions)

→

Stool-softeners (bulk forming, lubricant, surfactant)

→

Cathartics (saline, stimulant)

Prodrug of bulk-forming laxatives

Psyllium

Bulk-forming laxatives MOA

• Has the same impact as dietary fiber

• Available OTC

• Type of soluble fiber

• Gentle, not systemically absorbed, pulls water into the intestinal lumen

• Absorbs water creating gel-like substance in; interact with water to soften stools which increases bulk and stretches the intestinal wall stimulating peristalsis

• Produces soft, formed stool 1 to 3 days of use (takes some time to work)

• May also help lower cholesterol

SE of bulk-forming laxatives

SE are minimal but may include:

• Abd cramping, bloating, flatulence

• Rare cases bowel obstruction

C/I for bulk-forming laxatives

GI obstruction or fecal impaction

Nursing implications of bulk-forming laxatives

• Should be administered with a full glass of water or juice (at least 8 oz)

• Effect of laxative may take 1-3 days after use

• Can bind to others; take 1 hr before or 2 hrs after other meds

• Check label for added ingredients (e.g. added sugars or artificial sweeteners, sodium, or potassium → for patients with HF or diabetes)

Name the bulk-forming laxatives

• Psyllium (Metamucil)

• Methylcellulose (Methylcellulose)

• Polycarbophil (Polycarbophil)

What happens if a patient doesn’t take a bulk-forming laxative with water/juice (at least 8 oz)?

Bulk-forming laxatives mimic dietary fiber, so they are not absorbed by the GI but instead absorb water to make a gel-like substance to stimulate peristalsis. If not taken with water, it could form an obstruction

Lubricant laxatives

• Example is mineral oils

• Is not the laxative of choice

• Oral & rectal (enema) ROA

• Oral route for babies causes lipoid pneumonia (type of aspiration pneumonia)

• DNU long-term

AE of lubricant laxatives

Decreased absorption of fat-soluble vitamins with some drugs if given orally; lipid pneumonia in patients with dysphagia or newborns

Name the surfactant laxatives (stool softeners)

Docusate calcium or docusate sodium (Colace)

Surfactant laxatives MOA

• Facilitates penetration of water into the feces by altering the surface tension of stool (softens stool, makes it easier to pass)

• Produces soft stool 1-3 days after onset of treatment

Take these laxatives with a full glass of water

Surfactant laxatives and bulk-forming laxatives

Name the stimulant cathartics

• Bisacodyl (Dulcolax)

• Glycerin

• Senna

• Castor oil

Prodrug of surfactant laxatives

Docusate calcium or docusate sodium (Colace)

Prodrug of stimulant cathartics

Bisacodyl (Dulcolax)

Stimulant cathartics MOA

• Irritates the bowels and increase secretion of water and ions into the intestinal lumen → hyperactivity

• Produces semifluid stool within 6-12 hours

Take these laxatives on an empty stomach; do not take within an hour of drinking milk.

Stimulant laxatives

Why not take stimulant cathartics with milk?

Stimulant cathartics often come in an enteric-coated form; milk increases pH and can interfere with enteric coating and release the full dose

Laxative often overused by older adults

Stimulant cathartics → assess patient’s medication profile and OTC meds

Name the saline cathartics (osmotic cathartics)

• Magnesium salts (magnesium hydroxide, magnesium citrate, and magnesium sulfate)

• Sodium salts (sodium phosphate)

• Polyethylene glycol (MiraLax) 

• Polyethylene glycol-electrolyte solution (PEG-ES); brand name GoLYTELY

AKA osmotic laxatives

Saline cathartics

Saline cathartics MOA

• Laxative salts are poorly absorbed and draws water into intestinal lumen (osmotic pressure)

• Rapid effects (1/2 hr to 6 hrs)

Saline cathartics AE

• Fluid/electrolyte imbalance (rapid wasting of GI contents; GI fluid and electrolytes absorption imbalance)

• C/I in disorders that accumulate magnesium, sodium, phosphate, and potassium (e.g. HTN, HF, kidney disease)

PEG-ES Indication & MOA

• Saline cathartic used as a bowel cleansing solution prior to a procedure (e.g. colonoscopy or surgery)

• Usually ingest/drink 4L jug over 2-3 hrs

• Onset 30 min, evacuates bowels with 4 hrs

Drugs C/I for disorders that accumulate magnesium, sodium, phosphate, and potassium (e.g. HTN, HF, kidney disease)

Saline cathartics (AKA osmotic laxatives)

Polyethylene glycol (MiraLax) MOA

• Saline cathartic/osmotic laxative. Dissolved in fluids that patient drinks

• OTC drug

• Nonabsorbable compound, retains water in intestinal lumen

• Effects occur in 2-4 days

• Do not take this drug longer than 2 weeks

AE of osmotic laxatives (polyethylene glycol/Miralax)

• Nausea

• Abd bloating, cramping

• Flatulence

Laxative used for patients with hepatic encephalopathy, which produces ammonia → drug clears bowels so body will not absorb ammonia

Lactulose indication

Drug is used to clear bowels of potassium and prevent hyperkalemia

Sorbitol with sodium polystyrene sulfonate (Kayexalate)

Sorbitol mixed with activated charcoal

Used to clear GI of harmful substances

Excessive volume, fluidity, and frequency of bowel movements

Diarrhea

Causes of diarrhea

• Infection/inflammation

• Maldigestion

• Functional disorders of the bowels

• SE of medications

Unresolved diarrhea can cause

Dehydration and electrolyte depletion

Treatment of short-term diarrhea

• Replacement of fluids & electrolytes

• Eating bland foods

• Ongoing diarrhea requires medications

Name the opioid antidiarrheal agents

• Diphenoxylate with atropine (Lomotil)

• Loperamide (Imodium) OTC

Laxative that is a schedule V drug

Diphenoxylate with atropine

Nursing implications for opioid antidiarrheal agents

• Schedule V

• Recommended doses do not produce morphine/opioid-like SE

• Use w/ caution with hepatic or renal disease

AE of opioid antidiarrheals

Hypotension & respiratory depression

Opioid antidiarrheal that has low potential for drug use and can be bought OTC

Loperamide (Imodium)

Antidiarrheal that has BBW for torsades de pointes (arrhythmia), cardiac arrest, and death with high doses

Loperamide (Imodium)

Why is loperamide not scheduled even though it’s an opioid antidiarrheal?

Does not cross BBB

C/I for antidiarrheal agents

Diarrhea caused by toxins or parasitic agents → we want GI to get expel the toxins/parasitic agents

Adjuvant antidiarrheal agents

• Bismuth subsalicylate (Pepto-Bismol) → may have antibiotic, antiviral, antisecretory, anti-inflammation characteristics; use for prophylaxis of traveler’s diarrhea

• Octreotide

• Bulk-forming laxatives

• Enzymatic replacement (for diarrhea caused by lack of digestive enzymes)

• Antibiotics for bacterial enteritis

Adjuvant antidiarrheal that is used as prophylaxis for traveler’s diarrhea (diarrhea from contaminated food or water)

Bismuth subsalicylate (Pepto-Bismol)

Drug has risk for Reye’s syndrome in children < 18 y/o

Bismuth subsalicylate (Pepto-Bismol)

Avoid this antidiarrheal in patients with aspirin allergy

Bismuth subsalicylate (bismuth salicylate)

Medication that may cause temporary grayish stool/black tongue

Bismuth subsalicylate (bismuth salicylate)

Adjuvant antidiarrheal that is a form of somatostatin hormone that will decrease GI secretion and motility

Octreotide

Bulk-forming laxatives can be used as antidiarrheals because

They cause stool to become bulkier and less watery, and helps patient absorb extra fluids

How to treat diarrhea caused by lack of digestive enzymes?

Enzymatic replacement (e.g. pancreatin or lipase)

Do not take this drug longer than 2 weeks

Polyethylene glycol (MiraLax)

Bismuth salicylate (Pepto-Bismol) MOA

Contains bismuth + salicylate

• salicylate component: good at binding to gut microbes; effectively works as antibiotics) → can cause salicylism

• bismuth component: SE are severe constipation, grayish tongue, and black stool

S&S of salicylate toxicity

• CV: increased HR; QT prolongation

• CNS: tinnitus, hearing loss, dizziness, HA, confusion

• GI: NVD

• Metabolic: sweating, thirst, hyperventilation, metabolic acidosis

• CV: increased HR; QT prolongation

• CNS: tinnitus, hearing loss, dizziness, HA, confusion

• GI: NVD

• Metabolic: sweating, thirst, hyperventilation, metabolic acidosis

These are symptoms of

Salicylate toxicity (Pepto-Bismol/bismuth salicylate)

Drug that can cause salicylate toxicity

Bismuth salicylate (Pepto-Bismol)

How to treat salicylism (caused by Pepto-Bismol)

HCO3- dose to alkalize drug and urine pH; alkalizing urine pH means drug is not absorbed

You can eat fiber alone without fluid to treat constipation. True or false?

False

SE of bismuth salicylates (Pepto-Bismol)

• Salicylism

• Severe constipation, grayish tongue, and black stool

Long-term SE of bisacodyl (Dulcolax; stimulant cathartics)

Toxicity, GI upset

Administering this drug for babies or patients with dysphagia via the oral route causes lipid pneumonia (type of aspiration pneumonia)

Lubricant laxatives (mineral oils)

Antidiarrheal C/I

• Diarrhea can be a protective mechanism to expel toxic substances/pathogens from the body (e.g. C. diff or E. coli)

• If blood in stool = C/I

SE of stimulant cathartics

Diarrhea, GI upset, flatulence, electrolyte imbalances

If bulk-forming or lubricant laxatives do not work

1) Bisacodyl (Dulcolax); stimulant cathartics

• SE Diarrhea, GI upset, flatulence, electrolyte imbalances

• Can titrate

2) Magnesium citrate (saline cathartics/osmotic cathartics)

3) GoLytely (Go violently)

Infrequent and painful expulsion of hard, dry stools

Constipation

Constipation is a symptom and not a disease. True or false?

True

Causes of constipation

• Medication SE

• Low fiber diet

• Sedentary lifestyle

Lubricant laxatives (mineral oil) MOA

Lubricates fecal matter and slows colonic absorption of water from the fecal mass

Effects of lubricant laxatives (mineral oils) occur in

6-8 hours

Drug that is best used as an enema as PO route may have adverse effects

Lubricant laxatives (mineral oils)

How long do surfactant laxatives (stool softeners) take to work?

1-3 days

How long do bulk-forming laxatives take to work?

Take ~1 day to act and exerts full effect in about 2-3 days

Gentle laxatives

• Surfactant laxatives

• Bulk-forming laxatives

• Lubricant laxatives

Docusate sodium (Colace) and Docusate calcium are examples of what drug class?

Surfactant laxatives (stool softeners)

• Psyllium (Metamucil)

• Methylcellulose (Methylcellulose)

• Polycarbophil (Polycarbophil)

Are examples of what type of laxatives?

Bulk-forming laxatives

• Bisacodyl (Dulcolax)

• Glycerin

• Senna

• Castor oil

Are examples of what type of laxatives?

Stimulant cathartics

• Magnesium salts (magnesium hydroxide, magnesium citrate, and magnesium sulfate)

• Sodium salts (sodium phosphate)

• Polyethylene glycol (MiraLax) 

• Polyethylene glycol-electrolyte solution (PEG-ES); brand name GoLYTELY

These are examples of what type of laxatives?

Saline cathartics (osmotic cathartics)