14 - Constipation Flashcards
What is constipation?
Infrequent and/or unsatisfactory defecation fewer than 3 times per week
What are common symptoms that px complain of w/ constipation?
- Straining and/or pain
- Passing dry, hard stool
- Passing small stools
- Feelings of incomplete bowel evacuation
- Bloating or decreased stool frequency w/ distention
- Feeling of rectal blockage and abdominal discomfort
What is considered normal bowel habits?
Can range from 3 BM/day to 1 BM every 3 days
What is functional constipation?
Chronic constipation not caused by a drug, anatomic, or physiologic abnormality
What are some risk factors for constipation?
- Female
- Non-white
- Living in rural, northern, or mountainous areas in North America
- Over 65 y/o
- Fewer years of formal education
- Low caloric intake
- Increased number of medications
- Lower socioeconomic status
- Sedentary lifestyle
- Travelling
- Ignoring urge to defecate
What are some diseases that cause constipation?
- IBS, IBD
- Neurological (stroke, MS, Parkinson’s)
- Diabetes
- Chronic renal failure
- Carcinoma
- Psychiatric
- Anal fissures
What are some medications that can cause constipation?
- Antacids (aluminum and calcium)
- Anticholinergics
- Iron supplements
- Analgesics
- Antihypertensive agents
- Anticonvulsants
- Antipsychotics
What are some lifestyle factors that can cause constipation?
- Decreased/inadequate dietary fibre
- Inadequate intake of fluids
- Lack of exercise
- Travel
What are red flags for constipation?
- Sx lasting longer than 2 weeks (or no BM for 7 days) w/ laxative use
- Blood in stool (dark, tarry); mucous; rectal bleeding; severe pain w/ defecating; fever
- Persistent abdominal pain or severe pain when defecating
- Unexplained weight loss of over 5%
- Family history of colon cancer (esp. if px over 50 y/o)
- Anemia sx (fatigue, lethargy)
- Vomiting
- Under 2 y/o
- Unremitting nocturnal sx
- Recent abdominal surgery
- Chronic illness associated w constipation
- Eating disorder
- Moderate to extreme thirst
- Diarrhea alternating w/ constipation
- Rectal or abdominal mass
What can be done to prevent constipation?
- High fibre diet w/ adequate fluid consumption (min. 1.5 L/day)
- Routine, private toilet regimen
- Defecating when feeling urge
- Prophylactic laxative use (when taking a constipating medication or have chronic condition associated w/ constipation)
- Daily physical activity (moderate)
What is the general tx approach for constipation?
- Adjust diet to increase fibre and fluid intake
- Include some form of aerobic exercise
- Pharm intervention used in conjunction w/ lifestyle modification
- Select laxative based on px age, health status, and MOA of product
What are some fruits that can be recommended for constipation?
Apples, pears, prunes
___ can be recommended to children to help w/ constipation because it _____
Unbuttered popcorn; builds bulk in the stool
What are some non-pharms for constipation in children?
- Increase daily dietary fibre (popcorn, green peas, avocado, plums)
- Juice that contains sorbitol
- Toilet routine to try defecation 5-15 mins after each meal
- Biofeedback
What is the timeframe to effectiveness for OTC products for constipation?
- Agents that soften feces (bulk forming agents, emollients) = 12-72 hours
- Agents that result in soft or semisolid stool (stimulant laxatives) = 6-12 h
- Agents that cause watery evacuation (magnesium citrate, magnesium hydroxide, oral sodium phosphates) = 0.5-3 h
- Enemas = 5-15 mins
What is the MOA of bulk forming agents?
- Dissolve or swell in fluids of digestive tract by attracting water to hydrophilic sites
- Increase stool weight/volume and frequency
What is the first line agent for constipation in most cases?
Bulk forming agents b/c are considered dietary supplements instead of laxatives
Which px should avoid bulk forming agents?
Px w/ dehydration or that are fluid restricted
What is the recommended length of tx for bulk forming agents? Onset?
- Recommended for short-term use, but can be used long-term for prevention (if non-pharms aren’t enough)
- Onset = 1-3 days
What product is a stool softener?
Docusate sodium/calcium
What is the MOA of stool softeners? Onset?
- Helps water in bowel mix w/ fecal mass, causing softening
- Onset = 12-72 hours
Are stool softeners used for prevention or tx of constipation?
Only prevention
When are stool softeners highly ineffective?
- Preventing chronic opiate-induced constipation
- If inadequate dietary intake
When are stool softeners helpful?
Px who should not strain, and those w/ fissures or hemorrhoids
What are stool softeners often combined w/ for long term tx of opiate-induced constipation?
Sennosides/bisacodyl
How does mineral oil act as a laxative?
- Lubricates fecal material and intestinal mucosa
- Reduces reabsorption of water from GI tract, increasing fecal bulk
What is laxative jelly used for? How long can it be used? What is the dosage?
- For tx of occasional constipation
- Used for max. 1 week
- Dosage = single dose at bedtime
What is the difference between lubricants and stimulant laxatives?
- Same onset of action
- Stimulant laxatives have less side effects, so typically recommended over lubricants
When are stimulant laxatives used?
- Acute constipation for short periods of time
- First line for opiate-induced constipation
What is the onset of action for stimulant laxatives? When should they be taken?
- Onset = 6-12 hours
- Taken at bedtime
What are counselling notes about bisacodyl products?
- Enteric coated so shouldn’t be crushed or chewed
- Not to be taken w/ milk, antacids, or PPI’s
What is the MOA of osmotic laxatives?
Presence of ions draws water into intestine, increasing intraluminal pressure, which applies mechanical stimulus that increases intestinal motility
When is PEG 3350 used? For how long? What is the dosing? Onset of action?
- Indicated for short term use in px w/ constipation
- May be used long term as well (6 months)
- May be used for opioid-induced constipation
- Dosing = once daily
- Onset = 48-96 hours
What are common side effects of PEG 3350?
- Gas
- Cramping
- Bloating
- Diarrhea
What are some counselling tips regarding PEG 3350?
- Avoid other medications w/in 2 hours of use
- Indicated for adults 18+ only, unless recommended by physician for use in children (commonly recommended in children)
What is the safest and most effective product for constipation? Why?
- Glycerin suppository
- Minimal SE (rectal irritation) and no drug interactions
What is the MOA of glycerin suppositories? Onset?
- Osmotic effect and local irritation effect leads to drawing of water into rectum to stimulate BM
- Onset = 15-30 mins
What is a counselling tip for glycerin suppositories?
- Moisten w/ warm water before insertion
- Try to retain as long as possible
When can magnesium osmotic products be used? Why?
If px has normal renal function b/c frequently cause diarrhea and electrolyte imbalances
Magnesium products should be taken w/ ____ to prevent ______
Water; dehydration
When should enemas not be used?
Elderly
What should be done if constipation is not relieved w/in 48 hours of treatment?
Try another agent w/ a faster onset of action
What is the maximum length of treatment for acute constipation?
1 week
When should px be referred after attempting tx for constipation?
- No BM w/in 7 days
- Severe abdominal cramps and/or pain, N/V, rectal bleeding, rectal pain, anal fissures
- Dehydration (if diarrhea occurs)
- If sx last longer than 1 month (chronic)
What is the recommended tx for constipation in infants under 1 y/o?
- Increase amount of fluid (best to discuss w/ doctor)
- Pediatric glycerin suppositories to relieve rectal disimpaction (if under 2, then only under pediatrician recommendation)
What is the recommended tx for constipation in children 1 year or older?
- Increase dietary intake and fluids (sorbitol)
- First line = PEG, lactulose, sorbital
- Second line = MgOH, heavy mineral oil
Is pregnancy an automatic referral for constipation?
No b/c fairly common
What is the recommended tx for constipation in pregnancy and breastfeeding?
Non-pharms
- Increase fluid intake
- Increase dietary intake of fibre
- Try to time BM after meals
Can use pharm options to help in the meantime
- First line = bulk forming agent
- If stools remain hard, PEG
- Glycerin suppositories can be used occassionally
What is the recommended tx for constipation in the elderly?
- Increase dietary and fluid intake (unless fluid restricted, like heart failure or renal problems)
- Encourage px to establish routine time for BM (5-10 mins after meals)
- Can recommend bulk forming agents if not CI’d (must increase fluid as well)
- Can recommend glycerin suppositories, PEG, or stimulant laxatives (only for infrequent use)
What is the first line product for constipation in cancer and palliative px?
Stimulant laxatives
When should you refer cancer and palliative px w/ constipation?
No BM in 3 days
What is the recommendation for laxative use w/ other medications?
Wait 2 hours before and after taking laxatives to take other medications
What are common symptoms of laxative abuse?
- Diarrhea (severe, chronic, watery, frequently at night)
- Abdominal pain, N/V
- Weight loss, muscle weakness
- Electrolyte imbalance
What is the tx for laxative abuse?
- Referral
- If returning to pharmacy after being stabilized, recommend fibre or osmotic laxatives to establish normal BM
What are contraindications for bulk forming agents?
- Partial bowel obstruction
- Fluid restricted px
- Suspected fecal impaction
- Dysphagia
- GI strictures
- Throat problems
What are common side effects of bulk forming agents?
- Flatulence
- Bloating
- Cramping
- Psyllium = bronchospasm, anaphylaxis
- Polycarbophil = esophageal obstruction, fecal impaction
What are contraindications for stool softeners?
- Intestinal obstruction
- Acute abdominal pain
- N/V
What are common SE of stool softeners?
- Mild transient nausea
- GI cramps
- Occasional rash
What is a contraindication for lactulose use?
Galactose restricted px
What are common SE of lactulose, sorbitol, and PEG?
- Flatulence
- Abdominal cramps
- Nausea
What is a contraindication for sorbitol use?
Severe cardiopulmonary or renal impairment
What is a contraindication for PEG?
Renal disease
What is a contraindication for MgOH, Mg citrate, and sodium phosphate?
- Cardiac or renal disease
- Caution w/ dehydration
What are drug interactions w/ MgOH and Mg citrate?
Digoxin and tetracyclines
What are common SE for MgOH, Mg citrate, and sodium phosphate?
- Hypokalemia
- Abdominal cramps/pain
- N/V
- Dehydration w/ MgOH
What are contraindications for senna and bisacodyl?
- Undiagnosed rectal bleeding
- Signs of intestinal obstruction
- Appendicitis
What does bisacodyl interact w/?
Milk, antacids, and PPI’s
What are common SE for senna and bisacodyl?
- Abdominal pain
- Hypokalemia
- Diarrhea
- Dehydration
What is a counselling tip for senna?
May discolour urine red to pink or brown to black
