Ch. 39: Drug Therapy for Constipation and Elimination Problems

Constipation:

• infrequent expulsion of hard and dry stool that is painful

• can be associated with normal or slow bowel transit or bowel dysfunction

Risk Factors for Constipation:

• low-fiber diet

• high levels of processed foods

• low level of physical activity

• certain medications (opioids, antidepressants, antihistamines, blood pressure, and NASIDs)

• advanced age

Constipation Clinical Definition Adult:

• defined as 3 or fewer bowel movements (BM( a week and/or symptoms

• normal BMs should be soft, formed, and without pain

Constipation Clinical Definition Pediatric:

less than 4 years of age, look for these:

• less than 2 BMs a week w/painful BMs, large mass of stool in rectum, 1 episode of incontinence per week after toileting skills are acquired, painful stools

• greater than 4 years: 2 or less BMs a week, stool retention, painful BM, large diameter stools, history of stool retention

Non-pharmacological Lifestyle Treatment of Constipation:

increased dietary fiber

increase fruits, vegetables, whole grains; reduce processed foods

adequate fluid intake (2000 ml daily)

prebiotics and probiotics

behavior therapy (maintain routine-attempt BM at set times each day)

increase activity and exercise

Pharmacological Treatment of Constipation:

laxatives:

• bulk forming

• lubricant

• stool softeners

cathartics:

• stimulant

• saline

• misc.

Why use on constipation med over the other?

• different causes of constipation

• different patient needs

• different medical reasons to empty the bowels

Uses of Constipation Medications:

• relieve constipation in pregnant women, the elderly, and those with gastrointestinal (GI) dysfunction

• fecal impaction

• prevent straining for patients with coronary artery disease, cardiovascular disease and hemorrhoids

• empty bowels for procedure preparation (colonoscopy, barium, enema)

• to accelerate elimination of toxic substances

• prevent ammonia absorption of patients with hepatic encephalopathy

• to obtain a stool specimen for examination/excrete parasites after anthelminthic drugs are administered

• reduce serum cholesterol levels

Bulk Forming Laxatives

Prototype Psyllium (Metamucil):

• effects are similar to increased intake of dietary fiber

• acts by adding bulk and size to fecal matter; stimulates peristalsis/defecation and pulls water into intestine

• also used in conjunction with dietary changes to lower cholesterol

Psyllium (Metamucil):

prototype for Bulk Forming Laxatives

Pharmacokinetics of Bulk Forming Laxatives

Prototype Psyllium (Metamucil):

• works in 12-24 hours; can take up to 3 days to exert full effects

• excretion is in the stool

Use of Bulk Forming Laxatives in Children

Prototype Psyllium (Metamucil):

should only be taken under the supervision of a healthcare provider

Use of Bulk Forming Laxatives in Older Adults

Prototype Psyllium (Metamucil):

lifestyle changes are preferred; if needed, bulk-forming psyllium compund can be recommended on a regular basis

Contraindications of Bulk Forming Laxatives

Prototype Psyllium (Metamucil):

• undiagnosed abdominal pain

• known hypersensitivity

• intestinal obstructions

• fecal impaction

Nursing Implications for Bulk Laxatives: Interactions

Prototype Psyllium (Metamucil):

• can potentially interfere with nutrient/medication absorption

• laxative use may reduce or delay the absorption of certain medications (Carbamazepine, Digoxin, Warfarin, Lithium, and tricyclic antidepressants)

• take Psyllium 1 hour before or 2-4 hours after taking other medications

Nursing Implications for Bulk Laxatives: Medication Administration

Prototype Psyllium (Metamucil):

• take this drug with at least 8 oz of water

• only one capsule/dose should be taken at a time

Nursing Implications for Bulk Laxatives: Adverse Effects

Prototype Psyllium (Metamucil):

• severe flatulence

• bloating

• abdominal cramping

• nausea

• vomiting

• rectal bleeding

• esophageal or bowel obstruction

Nursing Implications for Bulk Laxatives: Therapeutic Effects

Prototype Psyllium (Metamucil):

relief of constipation in 12-72 hours

Other Drugs in the Bulk Laxative Class:

Lubricant Laxatives:

• mineral oil

• acts by lubricating feces/slowing absorption of water from feces

• not recommended for long-term use due to adverse effects

• available OTC

Other Drugs in the Bulk Laxative Class:

Surfactant Laxatives (stool softeners):

• prototype is docusate sodium (Colace)

• acts by decreasing fecal mass’s surface tension, allowing water to penetrate stool and soften it

• usually acts within 1-3. days, should be taken daily

Stimulant Cathartics

Prototype Bisacodyl (Dulcolax):

irritates intestine, pulls H20 into intestine, gives watery stools

Bisacodyl (Dulcolax):

prototype for Stimulant Cathartics

Stimulant Cathartics are the….

strongest laxatives and also the most abused

Oral Action for Stimulant Cathartics

Prototype Bisacodyl (Dulcolax):

6-12 hours, suppository action is 15 min-1 hour

Saline Cathartics

Prototype Milk of Magnesia (magnesium hydroxide):

• causes water retention in intestine, decreases transit time, gives rapid bowel elimination

• often used for pre-surgical bowel prep

• effects often begin in 30-60 minutes

Milk of Magnesia (magnesium hydroxide)

prototype for Saline Cathartics

Use for Cathartics in Children:

avoid in children less than 6 years of age unless approved by clinician and used short term

Use for Cathartics in Older Adults:

often used and overused in this population; lifestyle changes with bulk-forming laxatives are preferred treatment

Overuse of Cathartics can lead to….

rebound constipation and eventual loss of normal bowel function

Cathartics Contraindication:

• known hypersensitivity

• presence of undiagnosed abdominal pain, intestinal obstruction or fecal impaction

Use Saline Cathartics Cautiously In:

• congestive heart failure: can increase edema if cathartic contains sodium

• impaired renal function: can contain phosphate, sodium, potassium, and magnesium, affecting electrolyte balance

Nursing Implications for Cathartics: Preventing Interactions

• Bisacodyl should not be taken within an hour after ingesting milk (can cause drug to enter intestine too quickly) or antacids (can lead to cramping and vomiting

• drugs that decrease effects of Bisacodyl:

  • anticholinergic drugs

  • H2 receptor blockers

  • proton pump inhibitors

Nursing Implications for Cathartics: Medication Administration

should be taken on an empty stomach or at bedtime and swallowed whole

Nursing Implications for Cathartics: Adverse Effects

monitor for:

• nausea

• abdominal pain

• cramping

• weakness

Safety Alert for Bisacodyl:

• should not be used frequently or for more than a week

• can result in serum electrolyte and acid-base imbalances (hypocalcemia, hypokalemia, metabolic acidosis, or metabolic alkalosis)

IBS-Related Constipation Guanylate Cyclase-C Agonists

Prototype Linaclotide (Linzess):

• take on an empty stomach at least 30 minutes before breakfast

• high-fat breakfast may cause loose stool/frequent stools

• monitor patient for diarrhea, abdominal cramping/pain, nausea, weakness

• this class can also be used for chronic idiopathic constipation

IBS-Related Constipation Guanylate Cyclase-C Agonists

Prototype Linaclotide (Linzess): Black Box Warning

do not use linaclotide in children under 6; avoid in people from 6-18 years old; risk of serious dehydration

Linaclotide (Linzess):

prototype for Guanylate cyclase-C agonists

Misc. Agents Used for Constipation: Lactulose (Constulose, Kristalose)

used to treat constipation and hepatic encephalopathy (decreases production of ammonia)

Misc. Agents Used for Constipation: Lubiprostone (Amitiza)

used to treat chronic idiopathic constipation, opioid-induced constipation in adults and irritable bowel syndrome with constipation

Misc. Agents Used for Constipation: Sorbitol

often given with Kayexalate (used to treat hyperkalemia) and to prevent constipation

also given with activated charcoal to aid in eliminating toxins from the body

Misc. Agents Used for Constipation: Tegaserod (Zelnorm)

used as a short-term treatment of IBS with constipation in female patients less than 65

Misc. Agents Used for Constipation: Prucalopride (Motegrity)

• serotonin 5-HT4 receptor agonist used to treat chronic idiopathic constipation

• cause cause severe diarrhea (especially during the first week of use), dizziness, sleepiness, and suicidal ideation; monitor patients, especially those with history of mental health issues

Glycerin:

• irritant/stimulant and usually acts within 30 minutes

• available only as suppositories

Polyethylene Glycol-Electrolyte Solution(NuLYTELY):

• gives rapid bowel cleansing without causing significant changes in water and electrolytes

• often used for procedure preparation

Polyethylene Glycol Solution (Miralax):

used in solution to treat occasional constipation; works slowly over 1-3 days

Castor Oil:

stimulant/lubricant; can alter levels of fat-soluble vitamins, such as A, D, E, K

Senna:

• herbal/tea/supplement

• not FDA regulated

• dosage can vary widely; teach patients to use with care