Irritable bowel syndrome Flashcards
When does the onset of IBS usually occur?
Between 20-30 years old
Are males or females more likely to suffer?
Females are at least twice as likely to suffer
What is the incidence of IBS on the population?
10-20% of the population
What is the risk of IBS with a first degree relative?
Twice as likely
What is the aetiology of IBS?
No exact cause but food intolerances such as diary or gluten are known to be precursors.
Other factors include:
Post infective bowel dysfunction
Gut hypersensitivity
Altered colonic motility
Heightened pain sensation
Stress
What is the link between gastroenteritis and IBS?
1/6 patients who develop IBS have recently recovered from gastroenteritis
What type of disorder is IBS?
It is a functional disorder as there are no underlying gut pathology changes (as seen in IBD).
What tests are used in diagnosing IBS?
Blood tests/stool samples/colonoscopy may be used only to be able to rule out other conditions where pathology changes have occurred (IBD).
What are the main IBS symptoms?
- Abdominal cramping
- Diarrhoea/constipation/alternating
- Flatulence
- Bloating
- Urgency to defecate
What are some additional IBS symptoms?
- Acid indigestion
- Nausea
- Lethargy
- Eating may worsen symptoms
- Passing mucus in stools
How is a diagnosis of IBS made?
There must be abdominal pain present for at least 6 months which is:
Relieved by defecation, or: Increased/decreased bowel frequency or stool form
Plus at least 2 of the following:
Abdominal bloating/distension
Altered stool passage (straining, urgency, incomplete evacuation)
Worsened by eating
Passing mucus
How is a diagnosis made in secondary care?
Often the Rome IV classification is used in secondary care in order to make a diagnosis, which includes:
Abdominal pain 1 day per week in last 3 months
Symptoms began at least 6 months prior
Alongside >2 of the following:
Related to defecation
Change in stool frequency
Change in stool form
According to the Rome IV criteria, what are the four classifications of IBS?
IBS-C (constipation)
IBS-D (diarrhoea)
IBS-M (mixed)
IBS-U (unclassified)
What is the stool type criteria for a IBS-C diagnosis?
> 25% of stools are types 1/2
<25% are types 6/7
What is the stool type criteria for a IBS-D diagnosis?
> 25% of stools are types 6/7
<25% are types 1/2
What is the stool type criteria for a IBS-M diagnosis?
> 25% of stools are types 1/2 AND
25% of stools are types 6/7
What is the stool type criteria for a IBS-U diagnosis?
Person has IBS, but bowel habits can’t be categorised as above
Main treatments for IBS?
Antispasmodic drugs
* Antidepressants
* Laxatives
* Loperamide
* Linaclotide
Why are antispasmodics first line?
Because they are direct acting smooth muscle relaxants
What are the three types of antispasmodics used?
Alverine Citrate
Mebeverine
Peppermint oil capsules
What is the IBS dose for Alverine citrate?
60-120mg up to TDS
What is the IBS dose for Mebeverine?
135mg TDS (20 mins before food) or 200mg BD for modified release preparations
What is the IBS dose for Peppermint oil capsules?
1-2 capsules up to three times a day
Which other antispasmodics aren’t recommended for use?
Hyoscine butylbromide and Dicycloverine can also be used but tend to have more antimuscarinic effects despite being very effective
When are antispasmodics contra-indicated?
In intestinal obstruction or paralytic ileus due to affecting the motility of the drug
When are anti-depressants recommended in IBS?
For patients that are experiencing pain alongside their IBS but its use in IBS is unlicensed.
Usually given for patients that have not responded to first line treatments.
What is the first line anti-depressant for use in IBS?
Usually a tricyclic anti-depressant, at a notably lower dose than in mental health conditions.
Amitriptyline 10-30mg at night
What is the second line anti-depressant?
SSRI (Citalopram, Fluoxetine, Sertraline) due to their pain modulating/peripheral effects on GI motility
Due to their off label use, their isn’t one that is recommended above another but is decided by the prescriber.
Why is patient counselling important for anti-depressant drugs indicated for IBS?
May be alarmed when patients read the PIL due to predominate anti-depressant use
Which laxatives are not recommended in IBS?
Lactulose due to increasing gas production and therefore potentially worsening symptoms.
Any other laxative is fine for IBS (specifically constipation type IBS).
What is the dose for laxatives for IBS?
Dose should be titrated to symptoms
What is the licensing requirement for the sale of OTC Loperamide for IBS?
Loperamide can be brought OTC for acute diarrhoea in patients over the age of 12. However if a patient is purchasing the medication for diarrhoea relating to IBS they must be over 18 to purchase and be diagnosed with IBS.
What are the key points regarding the sale of Loperamide for IBS?
Only for attacks lasting up to 48 hours (refer if longer)
Can be used for 2 weeks maximum, as long as individual bouts are less
than 48 hours
When is Linaclotide recommended?
For moderate to severe IBS-C in adults that have IBS diagnosed for 12 months or longer.
And only if the maximum dose of laxatives have not worked
What dose of Linaclotide is recommended?
290mcg once daily 30 minutes before food
When should Linaclotide be avoided?
IBD or GI obstruction
How do anti-spasmodics work (Mebeverine)?
- It specifically acts on smooth muscle cells
- Blocks voltage operated sodium channels
- This prevents build up of intracellular calcium, leading to reduction in contractility
- This reduces symptoms of colonic hypermotility
What type of drug is Linaclotide?
Guanylate cyclase-c (GC-C) agonist
How does Linaclotide work?
GC-C activation leads to increased production of cyclic guanosine
monophosphate (cGMP) * Increased cGMP stimulates the cystic fibrosis transmembrane conductance regulator (CFTR) ion channel
* CFTR ion channel increases secretion of chloride and bicarbonate into the intestinal lumen (this increase moisture content)
* GI transit increased
What are the red flag IBS symptoms that would warrant referral?
- Unintentional weight loss
- Unexplained rectal bleeding
- Family history of bowel/ovarian cancer
- Loose stools for >6 weeks in patients >60 years old
- Anaemia
- Elevated inflammatory markers (?IBD)
- Abdominal/rectal masses
