IBS Flashcards
IBS definition
A functional gastrointestinal disorder, whose main symptoms are:
▪ recurrent abdominal pain,
▪ changes in the frequency or characteristics of stool
▪ abdominal distension
it is a life long condition that affects mostly women. other symptoms incliude abdominal pain or discomfort, disordered defaecation (either diarrhoea, or constipation with straining,
urgency, and incomplete evacuation), passage of mucus, bloating
symptoms of IBS are usually relieved by defaecation, true or false
note that cause of IBS unclear, but there theories of how it occurs, including genetic predisposition, inflammation, and changes in the gut.
true
note tha IBS is more prevalent in people less than 50yrs of age
how do we diagnose IBS
physical examination of the abdomen to check for swelling, pain, tenderness…etc
tests like endoscopy and colonoscopy
if abdominal pain associated with an alteration in either stool form or frequency, occurring for at least 6 months, then that is indicative of IBS
some non drug treatments for IBS
increase physical activity
Eat regularly, without missing meals or leaving long gaps between meals
Limit fresh fruit consumption to no more than 3 portions per day
increase soluble fibre intake and reduce insoluble fibre intake
increase fluid intake
Reduce caffeine, alcohol and fizzy drinks
Avoid sorbitol, should be avoided in patients with diarrhoea
If probiotics are being used, continue for at least 4 weeks and monitor the effect.
Probiotics are live bacteria that can help maintain a healthy gut microbiome. They can be found in foods like yogurt, sauerkraut, and kimchi, or taken as supplements
5-HT signalling and it’s effects on IBS
5-HT aka serotonin
In IBS, serotonin signaling is often dysregulated, contributing to symptoms like altered motility (constipation or diarrhea), visceral hypersensitivity (increased sensitivity to pain), and irregular GI secretion.
5-HT3 receptors are involved in the regulation of pain perception, motility, and secretion. Overactivation of these receptors can lead to increased gut motility and abdominal pain, both of which are common in IBS-D (diarrhea-predominant IBS).
**
5-HT4 receptors** play a role in stimulating peristalsis and enhancing GI motility.** Dysfunction or reduced activation of these receptors may be associated with IBS-C (constipation-predominant IBS), leading to delayed motility and constipation.**
majority of body’s serotonin located in the GI tract
what does MAO-A stand for, and what is it’s function in IBS
Monoamine oxidase A (MAO-A)
degrade serotonin (5-HT) by deaminating it into its inactive form. The level of serotonin in the gut, where it plays a critical role in motility and sensation, is partially regulated by MAO-A
can cause diarrhoea or constipation in IBS depending on whether levels are increased or decreased
some drug treatments for IBS
anti-spasmotics
laxatives
anti-motility drugs
Low-dose tricyclic antidepressants e.g.amitriptyline. only used if above treatments have not worked
antimuscarinics fall under anti-spasmotic treatments for IBS, true or false
true
anti-spasmotics are the same as anti-spasmolytics
name some anti-muscarinics
describe how anti-muscarinics act to prevent IBS
atropine, dicycloverine, propantheline, hyoscine
Acts as an antagonist at muscarinic cholinoceptors in the gut leading to reduced contractions – reduction in spasm
how does alverine work
it is an IBS treatment
inhibits L-type calcium channels in smooth muscle, decreasing contractions. This suppresses the duration of spontaneous contractions of the gut, preventing local ischemia and pain in the colonic wall evoked by
spasms
what class of drug is alverine
Is a selective 5-HT1A receptor antagonist
mebeverine shares the same class of drug
which drug does alverine work synergistically with to abolish the effects of stress induced colonic motility changes
simethicone
how mebeverine works
inhibits L-type calcium channels in smooth muscle, decreasing contractions.
it has a local anaesthetic effect
Reduces sensitivity of gut smooth muscles to stimuli that causes contraction
it also affects sodium channels, altering electrical activity and reduces muscle excitability, leading to fewer spasms
▪ Acts primarily on gut – minimal absorption
peppermint oil has similar mechanism of action to mebeverine, true or false
true
active agent in peppermint oil?
mentol
note that peppermint oil can decrease visceral pain, and this is mediated through the TRPM8 and/or TRPA1 receptors (transient
receptor potential cation channel) located in nerve endings in gut
mechanism of action of low dose tricyclic antidepressants
Blocks noradrenaline and 5-HT (serotonin) uptake by NET and SERT at presynaptic terminals
▪ Also binds to and prevents the actions of:
▪ alpha – adrenoceptors
▪ Histamine H1 receptors
▪ M1 muscarinic cholinoceptors
NET stands for norepinephrine transporter, and SERT stands for serotonin transporter
