Lower GI

Question 1

Define diahorrea?

Answer 1

Greater than 200mg of loose stool. Or frequency >3 times of loose stool.

Question 2

Describe the basic pathophysiology of enterotoxic bacteria?

Answer 2

Increases the movement of Cl- and and Na+ out of cells into the lumen which is followed by water.

Question 3

What is the most important principle in treating diahorrea?

Answer 3

Oral Rehydration Therapy

In diahorrea you lose water as well as solutes.

Question 4

When are antibiotics indicated?

Answer 4

In infectious diahorrea, it usually self limiting and often viral and therefore antibiotics are not beneficial and may just leave the patient prone to super infection.

May be indicated in traveler’s diahorrea, ciprofloxacin is used empirically.

Question 5

Describe the method of action of anti-motility drugs and the reason for use?

Answer 5

Gamma opioid receptor agonists (loperamide)
Activate opioid receptors which inhibits the release of ACh which reduces peristalsis.

Anti-muscarinics (dicycloverine)
Blocks ACh from binding on the muscarinic receptors and therefore reducing stimulation and peristalsis.

Used for symptomatic relief in infective diahorrea it may prolong the infection.

Question 6

Define constipation, and list the potential treatment options?

Answer 6

Less than 3 motions per week.

Dietary advice, eat more fibre.

Osmotic laxatives (enter the colon unchanged and are then converted to lactic and acetic acid by the bacteria, due to osmosis more water to enters the lumen)

Magnesium (osmotic effect and also causes more cholecystokinin to be released increasing GI motility)

Bulking agents: methylcellulose, ispaghula

Stimulant laxatives (stimulate GI tract) e.g senna extracts

Question 7

Describe the different treatment options for Irritable bowel syndrome?

Answer 7

Loperamide or lactulose (dependent on symptoms)

Anti-spasmodics (for abdominal cramps) e.g:

• Antimuscarinics e.g. inhibit parasympathetic activity
• Mebeverine: direct relaxant of GI smooth muscle - probably acting as a phosphodiesterase inhibitor

Amitryptaline: (TCA) low doses

• antimuscarinic affects
• some pain relief
• reduces the sensitivity of some of the sensory nerves in the lower GI tract

Question 8

Describe the pharmaceutical treatment of IBD?

Answer 8

5-Aminosalicylates:-5-ASA, Mesalazine , Suphasalazine-
Inhibits leukotriene and prostanoid formation, scavenge free radicals, decrease neutrophil chemotaxis.

Corticosteroids: to induce remission e.g prednisolone

Immunosuppresants:
Azathioprine, cyclosporine, methotrexate and infliximab (anti-TNF for severe crohn’s)

Question 9

Describe the important counselling points when prescribing the following immunosuppresants: azathioprine, methotrexate?

Answer 9

Azathioprine:
Very good at inducing remission. But:
Can cause pancreatitis and myelosupression (monitor FBC every 8 weeks)

Methotrexate:
Only a ONCE A WEEK dose.
Effective for Crohn’s but not UC.
Monitor FBC, U/Es and LFTs

Report fever/cough – may indicate infection due to neutropenia
Report cough/dyspnoea – may indicate pulmonary toxicity

Question 10

Describe the side effects of long term corticosteroid use?

Answer 10

Cushingoid moon face.
Central obesity.
Diabetes.
Thin frail skin and therefore easy bruising.
Immunosuppression (thrush from inhaled corticosteroids)
Osteoporosis.
Hypertension.