301 Diarrhoea & Constipation Flashcards
What is constipation?
Small, infrequent and difficult passage of stools
How many times a week is constipation classified as? And what types on the Bristol scale?
<2-3 per week
Type 1 or 2
Possible causes of constipation
- Diet and lifestyle (fibre, fluid, food intake, exercise)
- Improper bowel habits - not responding to gastrocolic reflex - urger to defaecate
- Physiological changes (pregnancy, old age)
- Medication
What medication commonly causes constipation?
- Supplements - iron, calcium
- Opioid analgesics (codeine, morphine)
- Antitussives (pholcodine, codeine)
- Verapamil
- Antidiarrhoeal drugs (imprudent use)
- Aluminium (in antacids)
- Anticholinergics
- Drugs with intrinsic anticholinergic effects (TCAs, phenothiazines, sedating antihistamines)
- Diuretics (if dehydration occurs)
Concurrent disorders that can cause constipation: endocrine disorders
Hypothyroidism, diabetes, chronic kidney disease
Concurrent disorders that can cause constipation: neurological conditions
Parkinson’s disease, spinal cord injury, stroke or multiple sclerosis
Concurrent disorders that can cause constipation: recent surgery
Scar tissue (adhesions) from past surgery can compress, squeeze or narrow intestine & rectum causing constipation
Concurrent disorders that can cause constipation: pregnancy
Hormonal changes or enlarged uterus pushes on intestine
Concurrent disorders that can cause constipation: other
Diverticulitis (bowel condition causing abdominal pain)
Bowel cancer
Counselling points with constipation in the elderly
NOT due to reduced bowel motility/tone
May be due to lifestyle changes & chronic illness
Most have normal frequency but strain at stool
May reflect dehydration state
Bowel cancer risk increases 50+
May use laxatives to treat & prevent
How do we assess constipation symptoms?
Assess symptoms, onset, frequency, accompanying symptoms & duration (acute or chronic)
What criteria should be present in constipation diagnosis?
2 criteria:
1. Change in bowel frequency for patient
2. Hard stools passed, often with difficulty & straining
What are accompanying symptoms of constipation?
Abdominal discomfort or bloating, nausea, blood or mucus in stool (refer!)
Acute vs chronic diarrhoea
A: >4 days
C: >3 months
When to refer constipation
- Blood/mucus in stools (tarry, red/black)
- Persistent abdominal pain, pain on defecation
- Unintentional weight loss (50+)
- Sudden unexplained bowel habit changes lasting 2+ weeks
- Constipation >1 week after laxative use or 2 weeks of dietary intervention
- Suspected laxative misuse
Lifestyle management of constipation
- Increase dietary intake of fibre (fruit and veg, wholegrains)
- Increase fluid intake
- Reduce refined carbs intake
- Regular exercise
- Respond to urge to defecate - gastro-colic reflex greatest after meals
Types of pharmacological management of constipation
- Bulk-forming laxatives
- Stimulant laxatives
- Osmotic laxatives
- Stool softeners
Types of laxatives with examples: bulk-forming
Soluble fiber forms bulkier stools, stimulating colon to contract push stool out (fybogel, methylcellulose)
Types of laxatives with examples: stimulant
Activate nerves control muscles in colon (Bisacodyl, Senna)
Types of laxatives with examples: osmotic
Pulls water from body parts into colon, to softens stool so it is easier to pass, they contain salt that holds water in colon (lactulose, magnesium hydroxide solution Dulcolax)
Types of laxatives with examples: stool softeners
Increase water and fat in stool to soften it (Docusate)
How do bulk-forming laxatives act?
How long for maximal effect?
Safe in pregnancy?
Useful when?
1st choice in what?
Options?
- Increase stool mass, traps water in stool, larger stool stimulates peristalsis & bowel movement
- Take several days for maximum effect
- Yes
- Prophylaxis & treatment in young & elderly
- Chronic constipation but requires adequate fluid intake & mobility (especially elderly)
- Ispaghula husk (fybogel), sterculia
Side effects of bulk-forming laxatives
Flatulence
Bloating
Abdominal discomfort
Precautions with bulk-forming laxatives
In moderate-severe renal impairment consider K+ content and fluid volume required
May not be acceptable
How do stimulant laxatives act?
Onset time?
Used in combo with bulk-forming when?
Can be used long term for?
- Stimulate nerve endings in plexus of bowel wall, increased peristalsis
- Oral 6-12 hours and rectal 15-60 mins
- Used when bulk-forming or osmotic laxatives are ineffective or inappropriate
- IBS & diverticulitis under medical supervision
- Spinal damage, prevention of opioid-induced constipation
Side effects of stimulant laxatives (includes Senna)
Abdominal discomfort, cramps, nausea
Fluid & electrolyte imbalance (prolonged/excessive doses)
Senna may cause red-brown discolouration of urine
Precautions of stimulant laxatives
Short term use preferred - risk of dehydration if diarrhoea occurs
Pregnancy - Senna used in pregnancy but best avoided or used occasionally - care in late weeks
How do osmotic laxatives act?
Types?
Onset time?
Used for?
- Retain fluid within bowel (osmotic effect) to stimulate peristalsis & formation of soft stool
- Saline or non-saline
- 2-4 days for effect
- Chronic constipation
Types of non-saline osmotic laxatives
- Sorbitol (Sorbilax liquid)
- Lactulose (Actilax, Duphalac or Lac-dol syrup)
- Macrogol (PEG) (Osmolax oral powder)
Types of saline osmotic laxatives
- Magnesium sulphate (Epsom salts oral)
- Sodium phosphate (Fleet ready-to-use enema)
- Sodium citrate/sorbitol (Microlax small volume enema (stimulant + osmotic))
- Sodium picosulphate/Mg (Picolax, Picoprep, stimulant + osmotic oral)
What are osmotic laxatives with electrolytes?
Why are they used?
Examples
- Contain macrogol (PEG) + electrolytes
- Reduced risk of electrolyte problems
- Colonlytely, Glycoprep, Movicol
What are larger doses of osmotic laxatives used for?
- Severe constipation
- Bowel prep prior to colonoscopy
- Faecal impaction
Side effects of osmotic laxatives
Rectal irritation, nausea, bloating
Cramps, fluid + electrolyte imbalance (reduced K+) - especially saline laxatives
Precautions with saline osmotic laxatives and why and when not to use
- (Especially sodium phosphate) - elderly, renal impairment, CV disease
- Increased risk of fluid/electrolyte problems - renal failure
- Intestinal obstruction, acute abdominal conditions (appendicitis), inflammatory bowel conditions
What are glycerol osmotic laxatives?
Used as?
Used for?
Onset time
- (Glycerin - glycerol suppositories), osmotic + lubricant + local stimulant
- Suppositories only - adult, child, infant
- Acute constipation when stools are present in lower rectum
- 1-2hrs for effect
What are stool softeners?
Onset time?
Useful when?
Valuable for?
Used in combo with?
- Lubricating or detergent action
- 1-3 days
- Patients with haemorrhoids, anal fissure, prevention of post-op straining
- Elderly & for opioid-induced constipation
- Other laxatives (coloxyl with senna)
Examples of stool softeners
- Docusate coloxyl tabs, supp, enema
- Poloxamer coloxyl drops for young children
- Liquid paraffin agarol
- Parachoc oral liquid
(1 & 2 have detergent action, 3 as a lubricant (aspiration risk))
What is detergent action in stool softeners?
Reduce surface tension of hard faeces - allows water to penetrate
Indications of suppositories/enemas
Onset time?
Used when?
Avoid when?
Types of enema?
- When oral laxatives are not effective
- For rapid relief (faeces in lower rectum) - onset of actions 30mins to 3hrs
- For occasional use only
- Avoid in patients with haemorrhoids or anal fissure
2 types of enemas: small and large volume enemas
How to use a small volume enema?
- Remove seal
- Squeeze tube slightly until a drop of liquid smears the tip of the enema (for easier insertion)
- Insert tube fully into rectum (half-length in children under 3 yrs)
- Squeeze shoulder of tube until empty
- Keeping tube squeezed tightly, withdraw nozzle
How to use suppositories
- Wash hands
- Lie on one side with your knees pulled up towards the chest
- Gently push suppository, pointed end first, into your back passage with your finger
- Push the suppository in as far as possible
- Lower your legs, roll over onto your stomach & remain still for a few minutes
- If you feel your body trying to expel the suppository, try to resist this
- Lie still & press your buttocks together
- Wash your hands
What is diarrhoea?
An increase in frequency of passage of soft or watery stools relative to persons usual bowel habit
Not a disease - symptom of underlying condition
Infection or GI disorder
What are the diarrhoea classes?
- Acute <7 days
- Persistent >14 days
- Chronic >1 month
Clinical features of diarrhoea
- N + V may be present prior to bout of acute diarrhoea
- Cramping, flatulence & tenderness may present
- Acute infective diarrhoea often watery in nature with no blood present
- Often resolved after 2-4 days
Possible causes of diarrhoea: in community pharmacy
- Viral and bacterial (most likely)
- Medication (likely)
- IBS, giardiasis, faecal impaction (less likely)
- UC & Crohn’s disease, colorectal cancer, malabsorption syndromes (least likely)
Possible causes of diarrhoea: medications
- Alpha blockers
- ACEIs
- Antacids (Mg salts)
- Antibiotics
- Metformin, acarbose
- SSRIs and SNRIs
- Beta blockers
- Dopaminergics
- NSAIDs
- PPIs
Conditions to rule out in diarrhoea
- Medicine-induced diarrhoea
- IBS
- Giardiasis
- Faecal impaction
- UC & Crohn’s disease
Questions to ask with diarrhoea symptoms
How frequent are bowel motions?
How severe is diarrhoea i.e. how loose are the stools? - loose or watery?
Colour of stool?
Questions to ask about onset and duration of diarrhoea
How long have they had symptoms?
Was it related to anything ingested? (check last few days)
Any recent dietary changes?
Recent overseas travel?
Factors to consider with diarrhoea
- Age: caution - children & elderly
- Any signs of dehydration? - dry mucous membranes, thirst, sunken eyes, decreased urine output, loss of skin elasticity
Management options in diarrhoea: oral rehydration (ORS)
- (Glucose 75mmol/L, Na 75mmol/L, K 20mmol/L, Chloride 65mmol/L & citrate 10mmol/L)
- Can be given to all patients groups
- Replace the fluid that is lost, especially important in young children & elderly
- Small amounts (50mls) best sipped every 5-10 mins
- Dose: Infants (50-100ml per kg for 1st 4 hours then by 5-7ml/kg per hour), Adults (2L in the 1st 24 hours then unrestricted normal fluids & 200-400ml ORS per loose stool or vomit)
Management options in diarrhoea: rice-based ORS
Often used in some developing countries where glucose may not be available
Diabetics
Management options in diarrhoea: loperamide
- Synthetic opioid analogue - exerts action via opioid receptors, slows GI tract time & increases capacity of gut
- 2 caps followed by 1 cap after each diarrhoeal bout, max dose 16mg (8 caps) per day
- Well tolerated but cramps, N + V, tiredness, dry mouth reported
Management options in diarrhoea: diphenoxylate
- Similar action to loperamide, however side effects are more common (drowsiness etc.)
- 2 tabs (5mg) four times a day, max 20mg (8 tabs) per day
Management options in diarrhoea: others
- Adsorbants (kaolin and pectin)
- Codeine
