2. Constipation and Diarrhoea Flashcards
What is the prevalence of Constipation?
• Prevalence
o Primary care- 20%
o Nursing Homes – 50%
What are some of the complications of Constipation?
- Serious complication is faecal compaction, can lead to faecal overflow and incontinence
- Faecal incontinence and constipation are risk factors for UTIs and pressure ulcers
- Significant association between constipation and physical aggression in NHs
- Can be cause of physical and physiological trauma
- Use of antipsycotics can compound constipation
How do you diagnose constipation?
• Subjective • Frequency • Consistency • Effort required (straining) • Pain • Discomfort ⇨ how often do you have bowel motion? o For people eating “normal western” diets, • Normal number of bowel actions can be anywhere between 2 bowel actions/week to 3 per/day
Describe the Rome III Criteria for Chronic constipation
• Presence of 2 or more of the following
o Straining during at least 25% of bowel movements
o Lumpy or hard stools in at least 25% of bowel movements
o Sensation of anorectal blockage for at least 25% of bowel movements
o Manual manouvres to facilitate at least 25% of bowel movement
o Fewer than 3 bowel movements each week.
• Loose stools are rarely present without laxatives
• These criteria must have been present for the last 3 months, with symptom onset at least 6 months prior to diagnosis
Name some of the causes of constipation
• Low fibre/fluid diet • Not enough exercise • Ignoring the call to go o Lack of privacy o Confined to bed Medications Disease
Name some of the medications that cause consitpation
o Eg. Aluminium and/or calcium antacids
o Iron preparations
o Opioids
o Verapamil
Name some of the diseases that can cause constipation
o Hypothyroidism, diabetes, hypercalcemia, bowel cancer or obstruction, neurological injuries and diseases such as MS, Parkinson’s disease, dementia and depression
• Chronic constipation does not predict bowel cancer
How do you manage constipation?
Lifestyle and diet! • Exercise o Reduces intestinal transit time o Stimulates regular bowel • Respond to the urge! o After waking, meals or exercise o Position education • Fluids to prevent dehydration • Reer for further investigation o Patients >50 • New onset or worsening symptoms • Alarm symptoms • Dietary Fibre
What are some dietary fibres we can include?
o Complex carbohydrates from plants
• Not digested in SI, and only partly in LI
• Insoluble fibre, eg. Vegetables, fruits, nuts, wholegrain, weat, brown rice, pumpkin and sunflower seeds
• Roughage, adds bulk to faeces and decreases transit time
• Soluble Fibre: oats, barely, apricots, bananas, cherries, grapefruit, and plums.
• High water holding capacity decrease water reabsorption in the LI
o Increase fibre content of diet gradually to reduce flatulence
o Not advisable in all patients- eg. Irritable bowel syndrome, may worse symptoms
Name some Polyols we can use for constipation
o Sorbitols, mannitol, xylitol
o Poorly absorbed in GIT
• Not considered dietary fibre
o Can cause bloating and wind due to fermentation within LI
o Occur naturaly in foods: apples, pears, stone fruits – high in pear and prune juice- “natural laxatives’
What are some ‘alarm symptoms’ that can be associated with more serious conditions?
- Acute or recent constipation
- Obstipation
- Rectal blood loss, melaena or mucous
- Weight loss
- Fever
- Rectal pain
- Change in stool caliber
- Anorexia, nausea, vomiting
- Family history of inflammatory bowel disease or colorectal cancer
- Aged over 50 years
Pharmacological treatment considered if constipation persists AFTER lifestyle changes. What medications?
• Bulking agents
• Osmotic laxatives
• Stimulant laxatives
o Long term use is not recommended
- Not good evidence to guide treatment
- However, long term treatment with bulking agents or lactulose is considered safe
- Specialist assessment is required if constipation remains refractory to treatment
Purgatives- Bulk Laxatives
• Bran, methylcellulose, sterculia agar
• Psyllium powder – Metamucil (plant derivative)
o All are polysaccharide polymers not broken down in the upper GIT (hence not really dietary fiber)
o They are hydrophilic organic polymers that sequester water in the stools (the big fiber load draws water into the gut)
o Forms a bulk hydrated mass (lots of water) leading to increased peristalsis thus improving feacal consistency
o Slow to act (days) but they have no side effects (as long as they are introduced gradually)
• Rapid increase in dose can cause flatulence & distension (bloating)
o Good fluid intake must be maintained or they wont work
• Onset of action 48-72 hours
o Important depending on how quickly you need to relive the patient
o Useful table in Therapeutic Guidelines Table 12 P154 (2006)
Purgatives: Osmotic Laxatives- what are the two types
Saline Purgatives
Lactulose
Purgatives: Osmotic Laxatives
SALINE PURGATIVES
Combine with polyol containing fruit juice (pear or prune juice)
Saline Purgatives
• More like salts => Saline purgatives (isotonic or hypotonic)
o Magnesium sulfate & magnesium hydroxide
o Increase osmotic load in the GIT Lumen ⇒ increasing fluid drawn into the GIT (due to increased salt) ⇒ increases transit of GIT contents into the colon ⇒ distension of the colon ⇒ purgation within an hour! (much faster acting)
• Onset of action
o Oral 0.5 – 3 hrs, rectal 2-30 mins
• Sides effects (Particular in children or in renal-compromised patients)
o Abdominal cramps
o Salts can cause heart block, neuromuscular block or CNS depression => use guidelines
Purgatives: Osmotic Laxatives: Lactulose
• Semi-synthetic disaccharide of fructose & galactose
o as opposed to salt (bit slower to act)
• Takes 2-3 days to act
• Side effects (high doses) can be quite uncomfortable: flatulence, cramps, diarrhea, electrolyte disturbance
• Onset of action oral 24-72 hours, rectal 5-30 mins
Purgatives: Faecal Softeners
• Docusate Sodium (Gwen’s coloxyl)
• Arachis oil (enema)
• Liquid Paraffin
• All act like a detergent in the GIT
o Soften the faeces – no direct action on the gut itself, but by softening the faeces they can improve transit time
o Weak stimulant of laxative actions
• Onset of action: oral 24-72 hours, rectal 5-20 mins
Purgatives: Stimulant Laxatives- types? & what is their action?
why should stimulant laxative use be limited!
Bisacodyl
Senna & Dantron
• Increase electrolyte & hence water secretion by the mucosa or inhibit water absorption (stimulates water secretion – more aggressive)
o Also increase peristalsis
• Probably via actions on the enteric NS
Stimulant laxative use should be limited
• None should be used in obstructive bowel condition!!
o Toxic megacolon
o Wont actually remove the obstruction, will just push everything against it
• Overuse can lead to an atonic colon
o Increasing doses are often needed over time
Dependency develops
Limited evidence for efficacy
Combination laxatives often available OTC
o Stimulant laxatives
o Coloxyl Senna;
Docusate sodium & Senna
All can cause dehydration unless taken in combination with fluids! This is super important.
Purgatives: Stimulant Laxatives- Bisacodyl
o Inhibits water absorption from the intestine
o Oral or suppository (suppository can act within 15-30 mins)
• Glycerol suppositories act the same way
• Similar to ducosate sodium
Purgatives: Stimulant Laxatives-
o Anthroquinone laxatives
o Stimulate water secretion following mucosal contact
o Also directly stimulates the myenteric plexus of the ENS ⇒ increased peristalsis & defecation
• Onset of action: oral 6-12 hours, rectal 5-60 minutes
NB: Stimulator = short term!! should not be used for long term
DIARRHOEA is a nonspecific symptom of many conditions
• Infections – viral, bacterial, protozoal • Adverse drug reactions o Potential side effect of almost any drug o Common with alcohol & antibiotics • Lactose intolerance • Irritable bowel syndrome • Inflammatory bowel disease • Malignancy • Malabsorption • Thyrotoxicosis • Diabetes • Scleroderma
Name some antidiarrhoeal agents
• Repercussions: a mild inconvenience or a medical emergency?
o One of the main causes of death of malnourished infants in the developing world
• Diarrhoea treatments
o Maintain fluids & electrolytes => rehydration is key – viruses will be self limiting & will usually pass!
o If required:
• Infection: use of anti-infective agents (abx)
• Use spasmolytic or anti-diarrhoea
o Most of the time the diarrhea itself doesn’t require treatment
Why would you treat it?
• Where it becomes a life-death situation you may want to treat & slow the loss of fluids
o Anti-microbial/anti-viral treatment
• Inflammatory bowel disease – must be careful because you can worsen symptoms
4 Main diarrhoeal syndromes
• Acute watery diarrhea (most common) o Eg rotovirus in children • Bloody diarrhea (acute or chronic) • Chronic watery diarrhea • Steatorrhoea (fatty stools)
Antimotility drugs are used in diarrhoea treatment
• Useful in symptom relief in adults
• Never use in infants and children
• REHYDRATION!!!!!
o Water & appropriate electrolytes
o Electrolyte in-balances such as hypernatremia dehydration can be fatal
o Range of electrolyte solutions available
• Eg pedialite
• Diluted fruit juice that “just tastes sweet”
• Frequent small volumes
Opiates – Can be used to treat diarrhea (very constipating)
Morphine
• Opiod receptors in the gut wall
• Increases tone & rhythmic contractions of the GI tract (particularly LI)
• Decrease in propulsion (expulsion)
• Contracts pyloric, ileocoic & anal sphincters => constipating
• Codeine
o Morphine congener (member of morphine family)
• Diphenoxylate & Loperamide
o Do not cross BBB!!
o So you get less euphoria then morphine & codeine
o Used only for their action on the gut
o More closely related structurally to pethidine congeners then straight morphine
o Loperamide is the drug of choice!!
o Enterohepatic recycling! Plasma half life approx. 10 hours
• All cause constipation, abdominal cramps, drowsiness & dizziness
How do you treat travellers diarrhoea
• Fluids & treat the infection
• If the diarrhea is severe & patient is losing a lot of fluid => Loperamide
o Selective action on the GIT => receptors on smooth muscle
o Decreases abdominal cramps associated with diarrhea
• This varies between patients; may develop cramps associated with subsequent constipation that may be caused by loperamide
o Decreases the passage of faeces
o May shorten the duration of illness (can improve health)
Explain Enterohepatic Cycling
• All of the opiates, Loperimide included, undergo significant enterohepatic recycling
o Drug reabsorption
o Drug recycling
o Maintains an elevated plasma concentration
o Drug Reservoir
• Everything taken from gut goes to liver first (first pass metabolism)
• Most drugs pass into general circulation, some stay in liver for further metabolism
o In liver (second phase metabolism) the drug may become conjugated => enters the bile duct
o Most drugs then pass in faeces. Opiate conjugant is broken down by bacteria in gut so the original drug is absorbed into the blood in its primary form
• Maintains a drug reservoir – drug supply is continually maintained
• Means have variable half lives depending on how much is recycled
• Loperamide t1/2 = approx. 10 hours
Spasmolytics can be used to treat diarrhoea
• Irritable bowel syndrome & diverticular disease
o Muscarinic receptor antagonists – inhibit parasympathetic activity
• Atropine
• Hyoscine
• Propantheline
• Dicyclverine
Adsorbents can be used to treat diarrhea
Symptomatic treatment
• Kaolin (aluminium silicate), pectin, chalk, charcoal, methyl cellulose
• Mechanism:
o Adsorb microorganisms or toxins, altering the intestinal flora
o Coat & protect the intestinal mucosa
• Efficacy not established
• Often mixed with other drugs (ie Kaolin & Morphine)
