Constipation & Diarrhea Flashcards
What is constipation?
Constipation is defined as infrequent bowel movements (less than three per week) or difficulty in passing stools (e.g. straining, lumpy/hard stools, pushing for more than 10 minutes, stool requiring digital evacuation or the sensation of incomplete evacuation)
What are some causes of constipation?
Constipation can be caused by diet, lifestyle, drugs, pregnancy. GI disorders and other medical conditions
What are some medical conditions that can cause constipation?
Irritable bowel syndrome (constipation-predominant), anal disorders (fissures, fistulae, rectal prolapse), multiple sclerosis, cerebrovascular events, Parkinson disease, spinal cord tumors, diabetes, hypothyroidism
When does constipation become chronic idiopathic constipation?
When constipation persists for several weeks or longer, and the cause is unknown
What is IBS-C?
Idiopathic constipation associated with chronic or recurrent abdominal discomfort that is relieved by defecation is termed irritable bowel syndrome with constipation (IBS-C)
What are examples of preferred treatment of constipation?
Non-drug treatments are preferred for constipation. These include increasing fluid intake (64 oz daily recommended), limiting caffeine and alcohol intake (to avoid dehydration) and increasing physical activity. Replacing refined foods with whole grain products, bran, fruits, vegetables, beans and other food high in fiber is useful
What are examples of key drugs that cause constipation?
Antacids (aluminum- and calcium-containing), antidiarrheals, clonidine, colesevelam, drugs with anticholinergic effects, iron, non-DHP CCB, opioids, sucralfate
What should be done if constipation does not improve with lifestyle measures?
One or more drug treatments can be used. Most medications are available OTC and can be tried for the initial treatment of IBS-C, CIC or opioid-induced constipation
What should be done if constipation is not improved after seven days of OTC treatment?
A healthcare provider should be consulted for further evaluation and, if appropriate, prescription medication can be considered
What are the most common side effects of drug treatment of constipation?
Diarrhea and abdominal cramping
What are the common classes of drugs used for the treatment of constipation?
Bulk-forming drugs, osmotics, stimulants, stool softeners, lubricants
Which OTC should be recommended for most adults with constipation?
Fiber
Which OTC should be recommended in iron-induced or hard stool constipation?
Docusate (stool softener)
Which OTC should be recommended for opioid-induced constipation?
Senna or bisacodyl (stimulant)
Which OTC should be recommended for pregnant women with constipation?
Fiber
Which OTC should be recommended when fast relief of constipation is needed?
- Adults: bisacodyl or glycerin suppository
- Children: glycerin suppository
How do bulk-forming drugs work?
Bulk-forming drugs and dietary fiber are the first-line treatments in most cases and the treatment of choice in pregnancy. They absorb water in the intestine, soaking up fluid and adding bulk to the stool which increases peristalsis and decreases stool transit time
How do osmotics work?
Osmotics contain large ions or molecules that are poorly absorbed. They draw fluid into the bowel lumen through osmosis, which distends the colon and increases peristalsis
How do stimulants work?
Stimulants directly stimulate neurons in the colon, causing peristaltic activity
Why do patients using chronic opioids require a stimulant laxative?
Opioids reduce peristalsis and prolong stool transit time
How do stool softeners work?
Stool softeners are emollients that reduce the surface tension of the stool oil-water interface, allowing more water and fat to mix with the stool which softens the fecal mass making defecation easier
How do lubricants work?
Lubricants coat the bowel and stool with a waterproof film which keeps moisture in the stool and makes defecation easier
What are some examples of bulk-forming drugs?
Psyllium (Metamucil), calcium polycarbophil, methylcellulose, wheat dextrin
What are some contraindications of Psyllium?
Fecal impaction and GI obstruction
What are some side effects of bulk-forming drugs?
Flatulence, abdominal cramping, bloating, bowel obstruction (if strictures present), choking (if powder forms are not taken with enough liquid)
What are some notes about bulk-forming drugs?
- Onset of action: 12-72 hours
- Adequate fluids are required; use caution if fluid restricted, if difficulty swallowing or if at risk for fecal impaction
- Calcium is a polyvalent cation; separate calcium polycarbophil from select drugs due to binding interaction
- Sugar-free options available
- Psyllium modestly improves cholesterol and blood glucose levels
What are some examples of osmotics?
Magnesium hydroxide (Milk of Magnesia), Miralax, Glycerin, Lactulose, Sodium phosphates (Fleet Enema), Sorbitolq
What are some contraindications of osmotics?
Anuria (sorbitol), low galactose diet (lactulose), GI obstruction (Miralax), galactosemia (lactitol)
What are some side effects of osmotics?
Electrolyte imbalance, abdominal cramping, abdominal distention, flatulence, dehydration, rectal irritation (suppository)
What are some side effects specific to Lactitol?
Upper respiratory tract infections, increased blood pressure, increased blood creatinine phosphokinase
What are some notes associated with all osmotics?
Onset of action is 30 min to 96 hours (oral), 5-30 min (rectal)
What are some notes about magnesium-containing osmotics?
Caution with renal impairment and do not use if severe renal impairment
What are some notes about Lactulose?
Used commonly for hepatic encephalopathy
What are some notes about glycerin suppositories?
Glycerin suppository used commonly in children who need to defecate quickly
What are some examples of stimulants?
Senna, Bisacodyl
What are some warnings associated with stimulants?
Avoid use with stomach pain, N/V or a sudden change in bowel movements that lasts > 2 weeks
What are some side effects of stimulants?
Abdominal cramping, electrolyte imbalance, rectal irritation (suppository)
What are some notes about stimulants?
- Onset of action 6-12 hours (oral), 15-60 mins (rectal)
- Take oral products at bedtime to induce a bowl movement the following morning; can give 30 mins after a meal to enhance peristalsis
- Chronic opioid use often requires a stimulant laxative
What is an example of an emollient?
Docusate sodium
What are some contraindications of emollients?
Abdominal pain, N/V, use with mineral oil, OTC use > 1 week
What are some side effects of emollients?
Abdominal cramping, throat irritation
What are some notes about emollients?
- Onset of action: 12 -72 hours (oral), 2-15 mins (rectal)
- Preferred when straining should be avoided (e.g. postpartum, post-MI, anal fissures, hemorrhoids)
- Use when stool is hard or dry
- Do not take docusate and mineral oil together (it increases the absorption of mineral oil)
What is an example of a lubricant?
Mineral oil
What are contraindications of lubricants?
Age < 6 years, pregnancy, bedridden patients, elderly, use > 1 week, difficulty swallowing
What are some side effects of lubricants?
Abdominal cramping, nausea, incontinence, rectal discharge
What are some notes about lubricants?
- Onset of action 6-8 hours (oral), 2-15 mins (rectal)
- Oral formulation generally not recommended due to safety concerns (e.g. risk of aspiration and lipid pneumonitis)
- Take a multivitamin at a different time due to malabsorption of fat-soluble vitamins
- Do not take docusate and mineral oil together (it increases the absorption of mineral oil)
What are prescription medications that can be used to treat constipation?
Lubiprostone, Guanylate cyclase C agonists, peripherally-acting, mu-opioid receptor antagonists, serotonin 5HT-4 receptor agonists
How does lubiprostone work?
The chloride channel activator lubiprostone acts on chloride channels in the gut, leading to increased fluid and peristalsis
How do guanylate cyclase C agonists work?
Guanylate cyclase C agonists increase chloride and bicarbonate secretion in to the lumen of the intestines, increasing the speed of GI transit and reducing abdominal pain
How do peripherally-acting, mu-opioid receptor antagonists work?
Peripherally-acting, mu-opioid receptor antagonists act on mu-opioid receptors in the GI tract, decreasing constipation
How do serotonin 5HT-4 receptor agonists work?
Serotonin 5HT-4 receptor agonists release acetylcholine which causes muscle contractions and increases gastrointestinal motility