IBS

Question 1

What are the symptoms of IBS?

Answer 1

IBS is generally perceived as a nuisance rather than serious, not life threatening and largely psychological. The symptoms of IBS include:
• Abdominal pain – any site, severe
•Abdominal bloating/distension
• Disordered bowel habit (diarrhoea, constipation, alternative between the two)
• Diarrhoea IBS – urgency and potentially incontinent
• Exaggerated gastro-colonic reflex – have severe cramping after eating and an urge to defecate
• Afraid to eat in public due to constipation/diarrhoea likelihood and can become house bound
• Sexual function – 80% complain that sexual activity is reduced due to IBS
• Extra-intestinal manifestations: nausea, thigh pain, backache, lethargy, urinary symptoms, gynaecological symptoms (pain during intercourse)
• Absent from work
• Poor quality of life

Question 2

What is the pathophysiology behind IBS?

Answer 2

The pathophysiology is multifactorial and was originally believed to be based on motility but is now regarded as a visceral sensitivity. The brain processing of abdominal signs and symptoms is varied in IBS patient – they process signals as more severe than most people. IBS tend to run in families and therefore there is an inheritance element to the condition. Inflammation, bacterial imbalance, dietary factors and psychological factors are also part of the pathophysiology.

Question 3

How is IBS diagnosed?

Answer 3

IBS should be a positive diagnosis, rather than a last-resort condition. Investigations should be appropriate rather than exhaustive as it tends to be currently.
IBS patients tend to associate symptoms with eating – they blame food, believe they have a dietary allergy and record their diet regularly.

Question 4

How is IBS managed non-pharmacologically?

Answer 4

The default treatment for IBS is cereal fibre – but studies show that the wheat fibre actually makes patients worse.

Food: Fructose, lactose, fructans, galactans, sorbitol are in many food products, especially fruit and vegetables– and cause problems in IBS.

Food allergies (IgE): probable not a problem in IBS, consider in highly atopic individuals.

Question 5

What pharmacological treatment is used for IBS (overview)?

Answer 5

Anti-spasmodics
Anti-cholinergics
Anti-smooth muscle drugs
Anti-diarrhoeals
Laxative
Anti-depressants
Serotonin drugs
Other: acupuncture, probiotics, behavioural approached

Question 6

List examples of antispasmodics, anti-cholinergics and anti-smooth muscle drugs

Answer 6

Antispasmodics: if the pain is caused by spasm, then relaxing the spasm should relieve the pain

Anticholinergics: Dicycloverine (Merbentyl), Hyoscine (Buscopan), Propantheline (Probanthine)

Anti-smooth muscle drugs: Mebeverine (Colofac), Alverine (Spasmonal), Peppermint (Colpermin)

Question 7

How do anti-diarrhoeals help IBS patients?

Answer 7

Anti-diarrhoeals: reduced the symptoms of IBS e.g. Loperamide, dephenoxylate, codeine phosphate

• Loperamide (first pass metabolism)
• Improves anal tone (incontinence)
• Regular use, Low dose
• No effect on pain, few systemic side effects
• Used in combination with antispasmodics

Question 8

What are the different types of laxatives and how do they work?

Answer 8

Laxatives
•Osmotics: Polyethylene Glycol, Lactulose, Magnesium salts
• Stimulant: Sodium Picosulphate, Bisacodyl, Senna
• Softeners: Docusate

The most commonly used is polyethylene glycol (movicol), and should be used regularly. There is no evidence of gut damage from laxatives, and the patient often needs re-assurance. IBS patients should avoid lactulose as it increases flatulence

Question 9

Why are serotonin drugs used in IBS?

Answer 9

Serotonin drugs e.g. Prucalopride

5-10% of the body’s serotonin is found in the brain, 80-90% is found in the bowel. Serotonin therefore affects motility, secretion and visceral sensitivity.

There are 3 main receptors used pharmacologically – 5HT1, 5-HT3, 5-HT4. Studies have shown that the diarrhoea-IBS patients have excess serotonin after a meal, whereas the constipation–IBS patients don’t have enough serotonin.
Serotonin drugs have been introduced but the side effects prevent regulation, except prucalopride which has been approved.

Question 10

What are probiotics, how do they work and what do they do?

Answer 10

Patients often believe their IBS occurred after gastroenteritis, and there is persistent inflammation of the bowel. Patients also claim that IBS occurred after antibiotic use and it has been shown that there is a bacterial imbalance in the bowel. The small bowel particularly has bacterial overgrowth.

Pro-biotics are drinks/capsules that contain live organisms that exert a potential health benefit on the host. Factors include;
o Enhance hosts anti-inflammatory and immune response
o Stimulate anti-inflammatory cytokines
o Pathogenic bacteria stimulate pro-inflammatory cytokines
o Restore balance between pro and anti-inflammatory cytokines
o Improve epithelial cell barrier
o Epithelial adhesion - exclusion of pathogens
o Inhibit bacterial translocation Inhibit growth of pathogens (e.g. salmonella)
o Inhibit adhesion of viruses (e.g. rotavirus)
o Elaborate active proteins and metabolites: immune modulation proteolytic/bacteriocidal properties toxin binding
o Reduce hyper-motility (animal model)
o Reduce visceral hypersensitivity (animal model)
o Reduce anxiety behaviour (animal model)

Lactobacillus
Bifidobacterium

Need to be adherent, acid and enzyme resistant, need to be given in high concentrations, and need to be living.
75% of trials regarding probiotics are positive

The different probiotics caused different symptom improvements, and not all organisms were effective.