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Inflammatory and GI diseases > Constipation > Flashcards

Constipation Flashcards

1
Q

Briefly describe the journey of food in the digestive system?

A

Food passes from the small intestine and passes along the caecum, colon and into the rectum by peristalsis.

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2
Q

How does drying of the stool occur?

A

When salts and water is reabsorbed it results in drying of the stools.

When excess drying occurs this will cause constipation or contributes to the development of constipation.

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3
Q

What is the role of bacteria in the intestine and the whole of the GI tract?

A
  1. They ferment non-digestible polysaccharides and some metabolites can be absorbed.
  2. They also produce Vitamin K and Biotin (Vitamin B7) which makes it available for the body to absorb
  3. They also produce gases from undigested polysaccharides
  4. Bacteria is essential for the development of the caecum and the lymphatic system
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4
Q

Where is feces stored and for how long?

A

Feces is stored in the rectum until theres an urge for defecation.

Stools are hard when they are stored in the rectum for too long due to excess water being reabsorbed from the stool.

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5
Q

What is the definition of constipation?

A

The passage of hard stools less frequently than the patients own normal pattern.

Constipation itself is a symptom NOT a disease. It can be a symptom of a disease or side effect of a medication.

Constipation is characterised by difficulty in opening the bowels:

  • If a patient is going less that 3 times a week
  • Straining to open the bowels more than 25% of occasions
  • Hard or pellet-like stool on more than 25% of occasions
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6
Q

What is chronic constipation?

A

If in the previous 6 months the patient has experienced symptoms of difficulty in opening bowels (less that 3x a week, straining, hard stools) for greater than 3 months

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7
Q

What factors can cause constipation? (aetiology)

A
  1. Age
  2. Diet
    - Low fibre
    - High animal fat
    - Inadequate fluid intake
    - Caffeine
    - Alcohol
  3. Poor bowel habits
    - Ignoring the urge to defecate
  4. Imaginary constipation
  5. Side effects of medications
  6. Laxative abuse
  7. Irritable bowel syndrome
  8. Intestinal obstruction
  9. Other diseases causing constipation
  10. Mechanical problems of the anus and rectum e.g. rectal prolapse
  11. Poor thyroid function (as main role of thyroid hormone is maintenance of regular bowel movement)
  12. Lead poisoning
  13. Pregnancy
  14. Travel
  15. Immobility (e.g. bed rest)
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8
Q

What factors are considered In the diagnosis of constipation?

A
  1. Medical history
  2. History of symptoms
    - Normal patterns of defecation
    - Other symptoms
    - Frequency and consistency of the stool, faecal impaction, incontinence
    - How long/intense are the symptoms?
    - Impact on daily life
  3. Medications
  4. Changes in diet and lifestyle
    - Change jobs
    - Holidays
    - Diet
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9
Q

What are the symptoms of constipation in children?

A

Cause/aetiology often unknown:
- May be due to change in diet

Symptoms:
- Infrequent bowel activity
- Foul smelling wind and stools
- Excessive flatulence (gas production)
- Irregular stool texture
- Abdominal pain, distension or discomfort
- Soiling/overflow

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10
Q

What are the main causes of constipation in older patients?

A
  • Age-related decline in GI motility (as you get older the GI system loses some of its elasticity and becomes less efficient)
  • Decreased mobility
  • Poor diet - low solid and liquid intake
  • Wasting of pelvic floor muscles
  • Side effects of medicines
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11
Q

What are the goals of constipation management?

A
  1. Achieve an individuals normal frequency of defecation
  2. Establishing regular, comfortable defecation
  3. Preventing laxative dependence
  4. Relieving discomfort
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12
Q

Give an example of bulking agents

A
  • Ispaghula husk
  • Methycellulose
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13
Q

Give examples of some stimulant laxatives

A
  • Bisacodyl (oral and rectal)
  • Senna
  • Dantron
  • Sodium picosulphate
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14
Q

Give examples of some faecal softeners

A
  • Docusate (oral and rectal)
  • Glycerol (suppository)
  • Arachis oil (enema)
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15
Q

Give examples of some osmotic laxatives

A
  • Lactulose
  • Macrogols
  • Magnesium hydroxide and Magnesium sulphate
  • Phosphate
  • Sodium citrate
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16
Q

What is acute constipation?

A

Has been lasting for less than 4 weeks

17
Q

What is chronic constipation?

A

Has been lasting for more than 4 weeks

18
Q

According to the guidelines what are the treatment steps for acute diarrhoea?

A
  1. First line: Lifestyle advice (increased fibre intake, adequate fluid intake and regular exercise) and manage any underlying causes (e.g. IBS or medications their on causing constipation)
  2. Bulk forming laxatives e.g. Ispahgula husk
    And/Or
  3. Osmotic laxatives: Macrogol
  4. Stimulant laxatives e.g. Senna
  5. Gradually reduce and stop after producing a soft, formed stool without straining at least three times per week
19
Q

According to the guidelines what are the treatment steps for chronic diarrhoea?

A
  1. First line: Lifestyle advice (increased fibre intake, adequate fluid intake and regular exercise) and manage any underlying causes (e.g. IBS or medications their on causing constipation)
  2. Bulk forming laxative e.g. Ispahgula husk
    And/Or
  3. Osmotic laxatives: Macrogol
  4. Stimulant laxatives e.g. Senna
  5. Prucalopride
  6. Gradually titrate the laxative doses up or down aiming to produce soft, formed stool without straining at least three times per week.
20
Q

What does faecal loading and faecal impaction mean?

A

Faecal loading is the build up of faecal matter in the colon.

  1. Soft stools:
  • First choice of treatment is a stimulant laxative e.g. Senna or Visacodyl. If unsuccessful ->
  • Next step is to consider Docusate (stool softener) or sodium citrate mini enema (osmotic laxative).

Facial impaction occurs when the material has been present for a longer period of time and the body has had a greater period of time to reabsorb water and salts from the stools. Ends up with dry hard stool which the patient can’t evacuate from the body.

2.Hard stools:

  • First choice of treatment is high dose oral macrogol - Were aiming by osmosis to draw water within the stools aiming to make it softer and easier to pass. If unsuccessful after 48 hours ->
  • Next step would be a stimulant laxative. E.g. Senna, and we would aim to get movement of the bowels within about 12 hours. If still unsuccessful ->
  • Next step is to use a glycerol suppository on its own or glycerol suppository + bisacodyl suppository. We would expect to have a bowel movement quite quickly (30mins-1hr). If still unsuccessful ->
  • Next step is to consider sodium phosphate (powerful osmotic laxative) enema or Arachis oil retention enema
21
Q

What are the treatment guidelines for patients with opioid induced constipation?

A

AVOID BULK FORMING LAXATIVES!
As bulk forming laxatives work by increasing faecal mass which causes the colon to become distended which stimulates peristalsis. However when patients are taking opioids, opioids reduce bowel contractility and this results in reaction in peristalsis hence has an antagonistic effect.

  1. First line: Osmotic laxative (or docusate) and stimulant (e.g. Senna or bisacodyl)
  2. Naloxegol
    - Peripherally acting mu-opioid receptor antagonist (PAMORA)
22
Q

What lifestyle advice is recommended for patients with constipation?

A
  1. High fibre diet
    - 30g fibre/day with sufficient fluid
    - Caution: Obstructive symptoms or fecal impaction
    - Ineffective in slow-transit constipation of defecatory disorders
    - Switch from ‘white’ to ‘wholemeal’
  2. Increase physical activity to ensure regular bowel movements
  3. Adequate fluid intake
    - 2L water per day
23
Q

What are the treatment guidelines for constipation in pregnancy and breastfeeding patients?

A

Pregnancy:
- Offer a bulk forming laxative
- Add or switch to an osmotic laxative
- Can consider a short course of a stimulant such as Senna (Never close to term! Can only be prescribed not OTC as this can cause labour contractions )
- Glycerol suppository

Breastfeeding:
- Offer a bulk forming laxative
- Add or switch to an osmotic laxative
- Can consider a short course of a stimulant such as Bisacodyl or Senna
- Glycerol suppository

24
Q

What are the treatment guidelines for constipation in children?

A

First line treatment - Macrogols + intervention for the child to make it easier for them to go to the toilet (e.g. scheduled toilet, stickers etc)

Second line or First line not tolerated - Add stimulant laxative

Third line - Add lactulose (or other softening laxative) if macrogol not tolerated

25
Q

What are bulk forming laxative and provide some examples?

A

Works by increasing the mass of your stools which in turn stimulates your bowel.

  1. Ispaghula husk e.g. Fybogel 3.5g/sachet
    - 1 sachet BD (12yrs and over)
    - Sachets which your pour into a full glass of water and take straight away
    - Preferably after meals (NOT just before bed)
    - Take 30min - 1hr before or after other medications
    -Remains effective despite long term use
  2. Methylcellulose e.g. Celevac
    - 500mg tablets
    - 3-6 tablets BD with at least 300ml of liquid
    - Break tablets in the mouth before swallowing

Do NOT take just before bed (as these laxatives increase the volume of stool, and you have less/absent peristalsis at night time, taking these will cause the opposite effect)

Ensure good fluid intake is maintained (to draw water into the stools)

Takes 2-3 days for effect

26
Q

Name examples of osmotic laxatives and faecal softeners with their counselling points.

A
  1. Macrogol E.g. Movicol, Cosmocol, Laxido
  • 1-3 sachets daily, in divided doses
  • Sachets to dissolve in 125ml of water
  • Can be high in sodium - Contraindicated in Hypertension, heart disease, Renal
  • Do not take other oral medicines 1 hour before or after dose
  • Takes 1-3 days for effect
  1. Lactulose
  • 15-45ml daily
  • Can cause bloating and colic
  • Caution if intolerant to lactulose
  • NO ISSUE for diabetic patients
  • Up to 2 days for effect
  1. Magnesium hydroxide E.g. Milk of Magnesia liquid
  • Mainly seen as liquid: 30-45ml PRN
  • Dose to be given at bedtime
  • Can be abused as it purgative (strong effect)
  • Commonly seen OTC (max 3 days)
  • Around 3-6 hours to take effect
  1. Docusate
    - Up to 500mg daily in divided doses
    - 12-72 hours for effect of tablets
    - 15mins for effect from suppositories
    - Softening agent and a stimulant
27
Q

Why are suppositories and enemas used for constipation?

A
  • These are often used for their quick action and strong laxative effect
  • Arachis oil enema contains PEANUT oil - beware for patients who are allergic *
28
Q

Name some examples of stimulant laxatives and their counselling points.

A

Stimulant laxatives are usually for short term use as they are said to cause a lazy bowel.

They work directly on the smooth muscle on the bowel, essentially promoting peristalsis.

  1. Senna E.g. Senokot:
  • Tablets and syrup
  • 7.5-15mg daily
  • Onset of action 8-12 hours
  • Syrup os unpleasant
  1. Dantron E.g. Co-danthramer or Co-danthrusate:
  • Co-danthramer includes PEG
  • Co-danthrusate includes docusate
  • Colours urine red
  • Avoid prolonged contact with skin
  • ONLY in terminally ill patients (potential carcinogen- causes cancer)
  • Oral solution
  • Onset of action 6-12 hours
  1. Sodium pico sulphate i.e. Dulcolax
  • 5-10mg once daily
  • Tablets and syrup
  • Onset of action 10-14hours
  1. Bisacodyl i.e. Duclolax
  • Acts on the small intestine
  • 5-10mg once daily; Increased if necessary up to 20mg once daily
  • Tablets act in 10-12 hours
  • Suppositories act in 20-60 minutes
  • Suppositories can cause local inflammation
29
Q

What is Prucalopride?

A
  • A selective serotonin 5HT4-receptor agonist with pro kinetic properties
  • Should only be prescribed by clinicians experienced in treating chronic constipation after careful review
  • 2mg tablets once daily, review treatment if no response after 4 weeks. (Reduced dose in elderly)
  • Side effects: Headache and GI disturbances
  • Increased doses will NOT improve response
  • 1-2 weeks for effect

Mechanism of action:

  • 5HT4 receptors are present in GI tract, especially myenteric plexus
  • 5HT4 activation leads to increased release of ACh
  • Hence we get an increase in rest and digest/parasympathetic drive
  • This increases peristalsis and propulsion
30
Q

What is the pharmacology of bulk forming laxatives?

A

The mechanism of action depends on type.

  • Typically, polysaccharides increase osmolality in gut when broken down, causing water retention
  • Retention of water in the GIT, so expanding and softening the stool
  • Bulkier stools distend the colon
  • Promotion of peristalsis via stimulating colonic mucosal receptors/stretch receptors
  • This leads to acetylcholine release (increased parasympathetic drive)
  • ACh activates muscarinic acetylcholine receptors (mostly M2 and M3 subtypes)
  • Increased peristalsis
  • Also creates mucus layer in intestinal lining which facilitates defecation
31
Q

What is the pharmacology of osmotic laxatives?

A
  • Poorly absorbed so act as osmotic agents and increase water retention in the gut lumen
  • As hyperosmolar agents, they are absorbed into stool by osmosis, making it softer
  • Softer stools are easier to pass
  • Many osmotic laxatives also contain Mg2+ (Magnesium)
  • Mg2+ triggers release of cholecystokinin (CCK)
  • CCK increases intestinal secretions and colonic motility
  • Decreases transit time through gut
32
Q

What is the pharmacology of stimulant laxatives?

A
  • Stimulate local reflexes of myenteric nerve plexus of the gut
  • Irritate nerve endings in wall of intestine
  • Motor effect on gut wall-increases propulsion
  • Increase secretion of water into the bowel
  • Increases gut motility and decreased transit time
33
Q

What is the pharmacology of stool softeners?

A
  • Sometimes known as emollient laxatives
  • Some work as surface wetting agents/surfactants (e.g. Docusate)
  • The mechanism of action is that they reduce the surface tension on the stool which allows water and fats to penetrate stool
  • This softens the stool, making it easier to pass
  • Docusate also has some stimulant activity
  • Arachis oil and Paraffin are examples of stool softeners which work by creating a barrier between stool and intestinal wall
  • This eases the passage of stool through intestine
  • Paraffin no longer popular due to concerns over carcinogenicity
34
Q

How to respond to constipation symptoms?

A

Children - Although there are laxatives licensed for children OTC, they require initial referral to a GP to have a physical examination.

Red flags:
- Pain on defecation - causing suppression of reflex
- Patients over 40 years with sudden change in bowel habits (no obvious cause)
- Greater than 14 days’ duration (no obvious cause)
- Associated fatigue
- Presence failure of laxatives
- Suspected laxative abuse

35
Q

What is the specific pharmacology of Senna?

A
  • Senna is a specific Anthraquinone laxative
  • Senna combines with sugars to form glycosides
  • Glycosides are molecules where the sugar is attached to a functional group via a glycosidic bond
  • In the gut the glycoside bond is hydrolysed by colonic bacteria to release irritant anthracene glycoside derivatives, specifically sennosides A and B
  • Sennosides A and B are absorbed and have direct action on the myenteric nerve plexus, increasing smooth muscle activity
  • Also postulated to increase PGE2 secretion (which increases gut motility)
  • Also reduce colonic water absorption which leads to a softer stool which is easier to pass.
36
Q

What is the pharmacology of PAMORAs?

A
  • PAMORAs are competitive antagonist at intestinal mu-opiod receptors
  • They prevent opioid activation of intestinal mu-opiod receptors
  • They target underlying opioid induced side effects i.e. reduced GI motility
  • Hence resulting in normal propulsion and peristalsis

Inflammatory and GI diseases (22 decks)

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