Diarrhoea Flashcards
describe diarrhoea
refers to the abnormal passing of loose or liquid stools.
In diarrhoea, there is increased frequency, volume or both. And it normally lasts less than 14 days
causes of diarrhoea
Infection(viral or bacterial)
Inflammatory bowel disease
Irritable bowel syndrome
stress/diet/post-infectious
Malignancy
Malabsorption
Malignancy is a medical term that describes the presence of cancerous cells that can spread and invade nearby tissues
what do we do if diarrhoea has lasted less that 4 weeks and what is suspected
what do we do when it has lasted more that 4 weeks and what is suspected
it is suspected to be infectious and a microbiological test of the stool is carried out
a non-infectious cause is suspected and tailored treatment is offered(i guess)
the types of diarrhoea and their descriptions
osmotic: Poorly absorbed solutes within the gut lumen lead to
retention of water into gut (can also be drawn into the
gut). Improves with starvation
secretory : Increased secretion or reduced reabsorption of salt
and water. Due to infection, laxative use, or
inflammatory mediators. Does not improve with
starvation
motility : Decreased transit time (i.e. moves quicker) through
GI tract. Water and electrolyte load from S.I. is too
great for the absorptive capacity of the colon.
inflammatory or exudative: Inflammatory insult to the mucosa eg ulcerative colitis,
or due to an infecting micro-organism causes loss of
integrity of the mucosa. Usually associated with
passage of blood, mucous and WBC’s
name some treatments of diarrhoea
Maintainance of fluid and electrolyte balance
▪ first priority – by means of oral rehydration
▪ can use oral rehydration powders
Use of anti-infective agents
Use of spasmolytic(anti-spasmodics) or other agents to act on the gut
what do you know about antimicrobials in the treatment of diarrhoea
not commonly used to treat diarrhoea
recommended in cases where there is;
* bloody diarrhoea and a high fever,
▪ severe diarrhoea following travelling,
▪ certain infections such as cholera and severe dysentery
▪ people who have specific bacteria or parasites in their
stool
what do you know about the mechanism of opiod related drugs in the treatment of diarrhoea
mechanism:
they increase the tone and rhythmic contractions of the intestine
Decrease propulsive activity ie peristalsis in the intestines.
Pyloric, ileocolic and anal sphincters are contracted
Tone of large intestine is markedly increased
Overall effect is constipating
note that opiods may enhance the the depressant effects of barbiturates, alcohol,
narcotics, tranquilizers, and sedatives
Opioids bind to mu-opioid receptors (MORs) in the gastrointestinal tract, particularly in the myenteric and submucosal plexuses.
opiods increase rhythmic contractions of the intestines but that does not increase propulsion because Opioids increase segmental contractions, which are non-propulsive because they churn contents in place rather than moving them forward.
loperamide readily penetrates the blood brain barrier, true or false
false
name some opiods used in diarrhoea treatment
loperamide(imodium)
codeine
diphenoxylate (Lomotil)
name the contents in the formula for the ORS recommended by WHO and UNICEF
sodium chloride
Anhydrous Glucose
Potassium Chloride
Trisodium citrate/dihydrate
how does loperamide work
it is an antimotility drug, so it slows down the passage of food through the gut(intestines), so more water is absorbed from the content of the gut, making it more solid and less loose.
Loperamide effects on myenteric plexus
and submucosal plexus?
plexus a branching network of vessels or nerves.
Loperamide acts as a mu-opioid receptor agonist, which stimulates the secretion of inhibitory neurotransmitters in the myenteric plexus. This increases non-propulsive contractions in the intestine, which decreases peristalsis and allows more time for absorption.
describe the mechanism of action of loperamide in the myentric plexus and submucosal plexus, in terms in neurotransmitter release
Loperamide binds to mu-opioid receptors in the myenteric plexus. This inhibits the release of excitatory neurotransmitters such as acetylcholine and substance P, which are essential for stimulating muscle contractions and motility.
cAMP and PKA levels decreased, which therefore decreases calcium influx through voltage-gated calcium channels.
Lower intracellular calcium impairs neurotransmitter release, further reducing motility and promoting intestinal constipation.
The inhibition of calcium influx reduces the activation of ATP-sensitive potassium (K_ATP) channels, which are influenced by intracellular calcium levels. This contributes to the overall reduction in motility and muscle contraction. Additionally, loperamide’s effects on calcium and potassium channels reduce excitability and motor activity in the gut.
note the effect is similar in both plexuses.
important thing to note about the submucosal plexus is that fluid secretion is inhibited
loperamide effects on enterocytes
enterocytes are cells in the small intestines
affects enterocytes by reducing the release of acetylcholine and prostaglandins, which inhibits peristaltic movement
myentric and submucosal plexus functions
myentric plexus controls the movement of the gastrointestinal tract by regulating the contraction and relaxation of the gut’s smooth muscles
submucosal plexus innervates the muscularis mucosae, which regulates peristaltic activity
they both have similar function, which is regulating peristalsis
state some beneficial effects of loperamide
By decreasing propulsive activity transit time is increased which allows more time for reabsorption
▪ By preventing secretion into the gut
▪ Also inhibits pacemaker potentials on interstitial cells of Cajal
Increases tone of anal sphincter which reduces incontinence and urgency
Interstitial cells of Cajal are the pacemaker cells in the GI muscles, generating electrical activity that determines the frequency, direction, and velocity of peristaltic contractions
how does Racecadotril work to treat diarrhoea
antisecretory agent that inhibits enkephalinase, an enzyme that breaks down enkephalins. Enkephalins are natural peptides that reduce intestinal fluid secretion by interacting with opioid receptors in the gut. By inhibiting enkephalinase, racecadotril increases enkephalin levels, reducing excessive fluid secretion during diarrhea without affecting basal secretion.
Reduces hypersecretion of water and electrolytes into the intestinal lumen
Racecadotril does not affect basal secretory activity, true or false
“basal secretory activity” refers to the natural, ongoing secretion of fluids and electrolytes by the intestines under normal, unstimulated conditions
true
Racecadotril modifies intestinal transit time.
false, it does not
how do locally acting antidiarrhoeals work
how many forms of them are there, name them
Act on the bowel wall to soothe and reduce irritation of the mucous lining
2
Adsorbents
Intestinal Secretory Inhibitors
Adsorbents work by binding to toxins, bacteria, or other harmful substances in the gut, preventing them from irritating the intestinal lining and contributing to diarrhea. This helps to reduce the stool volume and absorb excess fluid in the intestines.
These agents work by inhibiting the secretion of fluids and electrolytes into the intestines, which helps control the excessive fluid loss that occurs during diarrhea.
name some locally acting antidiarrhoeals
kaolin
▪ pectin
▪ activated charcoal
▪ bismuth
▪ charcoal
▪ methylcellulose
▪ activated attapulgite (magnesium aluminium silicate)
note these are all adsorbents
what do you know about the use of pectic and kaolin as antidiarrhoeals
they work by that work by adsorbing irritants and soothing intestinal mucosa
Aren’t absorbed or distributed
they are excreted in the faeces
they can interfere with the absorption of other drugs, so wait 2 hours after taking them to take other drugs
pectin= hydrated magnesium aluminium silicate
kaolin= indigestible carbohydrate
whihc between kaolin and pectin decreases ph in the intestinal lumen, to provide a soothing effect on irritated intestinal mucosa
pectin
Kaolin works by adsorbing substances but does not significantly affect the pH
when do we use the intestinal flora modifier and how they work
they are used if the growth of intestinal flora is modified due to antibiotic use
the provide the GI tract with normal intestinal flora
when is faecal transplanted opted for in the treatment of diarrhoea
advantage of the Faecal transplant
if all other treatments have failed.
it helps to restore a healthy gut microbiota
it refers to the instillation of stool from a healthy donor into another person
administered by enema, transcoionic infusion or nasoduodenal or nasogastric infusion
