IBS Flashcards
What is IBS?
Irritable Bowel Syndrome
- Group of functional bowel disorders
- Cause is unknown
What can some causes of IBS be?
- Immune response (inflammation)
- Gut microbiome
- Impaired mucosal functions
- Nerve sensitization
- Infection
- Altered expression + release of mucosal and immune mediators
- Altered gene expression profiles
What are some risk factors of IBS?
- Personal factors
- Somatic issues
- Psychological factors
- Social conditions
What are some activators of pathophysiology in IBS?
- Gut microbiome
- Mast cells
- Serotonin: 5-hydroxytryptamine
- TNF
Can IBS be due to genes?
It can be but there is not much evidence.
What is the some causes of IBS?
- Genetic factors
- Environmental factors
- Changes in gene expression (brain-gut axis)
- Epigenetic factors
What are some of the symptoms a patient may present with in IBS?
Person has abdominal pain or discomfort that is relieved by defaecation:
- Altered stool passage
- Abdominal bloating
- Symptoms made worse by eating
- Passage of mucus
What are some tests that are taken to exclude other diagnosis?
- FBC
- Erythrocyte sedimentation rate
- C-reactive protein
- Antibody testing for coeliac disease
Patients with IBS are more likely to have constipation or diarrhoea?
Both.
What are the 4 sub-classifications of IBS?
- Diarrhoea-predominant IBS (IBS-D)
- Constipation-predominant IBS (IBS-C)
- Mixed IBS (IBS-M)
- Unclassified IBS (IBS-U)
What are the main targets to treat IBS?
To treat:
- Pain
- Spasms
- Diarrhoea
- Constipation
- Anxiety
What are the therapies for IBS?
- Dietary and lifestyle advice
- Antispasmodic agents
- Laxatives (IBS-C)
-> Linaclotide if laxatives ineffective and constipation for >12 months - Loperamide (IBS-D)
- Selective Serotonin Reuptake Inhibitor (SSRI) for abdominal pain
- Low dose tricyclic antidepressants (TCAs) if other therapies provide no relief
What are some drugs, their generic name and mechanism for treatment of IBS?
Hyoscine -> Buscopan -> Anticholinergic
Mebeverine -> Colofac -> Antispasmodic
Peppermint oil -> Colpermin -> Antispasmodic
How do anticholinergics like hyoscine work?
Blocks the cholinergic receptor which ACh binds to when released into the synaptic cleft.
-> Relaxes smooth muscle and prevents spasms
How do anticholinergics like Mebervine work in IBS?
Acetylcholine receptor antagonist
-> relaxes smooth muscle and anti spasmodic
What is a treatment for IBS-C?
Laxatives
- Bulk forming
- Osmotic laxatives
- Faecal softener
- Stimulant
How is serotonin involved in IBS?
Major role in modulating intestinal movement and perception of pain.
Individuals with IBS
- imbalance of serotonin in the gut
- Improper reaction of the digestive system to serotonin
- Faulty communication between serotonin in the gut and the brain and spinal cord
What is prucalopride used for?
5-HT4 agonist used for IBS-C when other laxatives don’t work:
-> accelerate gastric emptying
-> accelerate movement of bowels
-> Increase stool water content
Does the 5HT-4 agonist cause contraction or relaxation?
Contraction
-> used in IBS-C
How does linaclotide work?
- Binds to Guanylate Cyclase C receptor (CG-C)
- Increase in cyclic Guanosine Monophosphate cGMP
- Activates Cystic Fibrosis transmembrane conductance regulator (CFTR)
- CFTR pumps salts and water into intestines
What is used for the treatment for IBS-D?
Loperamide
-> opioid receptor agonist
What are the functions of loperamide?
- Reduces peristalsis
- Increase transit time
- Enhance water and electrolyte reabsorption
- Reduce gut secretions
